Systematic review of randomized controlled trials of low-carbohydrate vs. low-fat/low-calorie diets in the management of obesity and its comorbidities

The effect of low-carbohydrate diets, based on changes in intake of dietary saturated fats on circulating TNF-α and interleukin- 6 levels in adults: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Low-carbohydrate diets (LCDs) have been associated with inflammation while there is still conflicting evidence regarding the effects of this type of diet on inflammatory markers and the clinical benefit of them remains uncertain. So, we aimed to ascertain the effects of LCDs on serum concentrations of tumor necrosis factor alpha (TNF-α) and interleukin- 6 (IL- 6) by performing a systematic review and meta-analysis of randomized clinical trials (RCTs).

METHODS

The online databases PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, Web of Science, and Scopus were comprehensively searched up to February 2024, to find pertinent RCTs. Pooled weighted mean difference (WMD) with 95% confidence intervals (CIs) were calculated using the random-effects model.

RESULTS

This meta-analysis of 33 studies assessed a total of 2106 adults irrespective of their health status. Compared with control group, participants on LCDs experienced a decline in IL- 6 levels (WMD: - 0.31 pg/mL; 95% CI: - 0.49 to - 0.12; P = 0.001). However, no significant effect was revealed for TNF-α (WMD: - 0.02 pg/mL; 95% CI: - 0.08 to - 0.03; P = 0.449). Stratification analyses indicated that beneficial effects of LCDs on inflammatory cytokines (WMD: - 0.28 pg/mL; 95% CI: - 0.47 to - 0.10; P = 0.003, WMD: - 0.26 pg/mL; 95% CI: - 0.48 to - 0.03; P = 0.027, for TNF-α and IL- 6, respectively) were stronger when carbohydrate intake was < 10%. The results of Meta-regression analyses suggested that baseline level of both markers remained as a strong predictor of the effect size (P = 0.038 and P = 0.001 for TNF-α and IL- 6, respectively).

CONCLUSION

Adherence to LCDs appeared to be effective at improving inflammatory cytokines particularly, when carbohydrate intake was restricted to less than 10% of total energy. Nevertheless, further rigorously designed clinical trials considering factors such as race and genetic, the sources and quality of dietary carbohydrates, protein, and fat are required to gain a deeper understanding of the impact of LCDs on inflammatory markers.

TRIAL REGISTRATION

PROSPERO, registration no: CRD42023387452.

Low-Carbohydrate (Ketogenic) Diet in Children with Obesity: Part 1-Diet Impact on Anthropometric Indicators and Indicators of Metabolic Syndrome and Insulin Resistance

BACKGROUND

The ketogenic diet has been successfully used in the last 100 years in the treatment of epilepsy and other neurological disorders. In recent decades, it gained wider application in the treatment of obesity, metabolic syndrome, and type 2 diabetes. However, there have been only a few studies on its use in children with obesity and associated metabolic disorders.

OBJECTIVES

To determine the clinical and metabolic effects of a well-formulated low-carbohydrate (ketogenic) diet in children with obesity.

METHODS

One hundred children with obesity and metabolic disorders underwent initial anthropometric, laboratory, and ultrasound examinations. They were placed on a well-formulated ketogenic diet and monitored for 4 months. The 58 patients who completed the study underwent follow-up examinations to assess the effects of the diet on anthropometric, clinical, and laboratory markers of metabolic syndrome and insulin resistance, cardiovascular risk factors, and certain hormone levels. Compliance with the diet, common difficulties in adhering to it, side effects, and positive changes in the patients' health were analyzed.

RESULTS

At the end of the study, the average weight loss for the entire group was 6.45 kg, with a reduction in BMI of 3.12 kg/m2. Significant improvements were also observed in insulin resistance indicators, including fasting insulin levels, HOMA-IR index, QUICKI (p < 0.0001), and adiponectin (p = 0.04). The cases of hepatosteatosis decreased twofold, the number of patients with arterial hypertension was significantly reduced, as well as the number of children receiving antihypertensive therapy. Additionally, the number of patients meeting the criteria for metabolic syndrome decreased threefold.

CONCLUSIONS

A well-formulated short-term ketogenic diet is effective in treating obesity, metabolic syndrome, and related comorbidities, and can be part of a comprehensive approach for these patients.

The impact of snacking habits and physical activity on body composition in overweight and obese adolescents: A longitudinal study differentiating home and school environments

With rising incomes in developing countries, the required necessary physical activity declines and the availability of snacks increases, further causing obesity in adolescents. The study was a longitudinal two-stage observational study of 74 overweight and obesity adolescents distinguishing between school and home environment phases. Data were collected at three time points (mid-semester (T0), end of semester (T1), and end of the winter holidays (T2)), and explorations were conducted using multivariate linear regression and Granger causality tests to investigate how changes in moderate-to-vigorous physical activity(MVPA), snacking habits (proportion of snack calorie, PSC; proportion of snack calories from protein, PSCP) in multiple stages and how their changes affect body composition. The results showed that during the semester phase, increases in ΔMVPA and ΔPSCP and decreases in ΔPSC were associated with decreases in ΔBFP (Δ = post-timepoint value - pre-timepoint value). During the holiday phase, decreases in ΔPSCP, MVPA (T1), and PSCP (T1), and increases in ΔPSC were associated with increases in ΔBFP. Only MVPA having a positive predictive effect causally on FFM. Snacking habits have a significant impact on body composition changes in adolescents, and reducing snack intake and choosing high-protein snacks are critical to controlling obesity in adolescents, especially during the holiday period. Strategies to increase MVPA should also be implemented to increase FFM briefly indirectly control obesity.

The Impact of Ketogenic Nutrition on Obesity and Metabolic Health: Mechanisms and Clinical Implications

The ketogenic diet (KD) has recently gained increasing popularity. This high-fat, adequate-protein, and carbohydrate-poor eating pattern leads to nutritional ketosis. The KD has long been known for its antidiabetic and antiepileptic effects and has been used therapeutically in these contexts. Recently, the KD, due to its effectiveness in inducing weight loss, has also been proposed as a possible approach to treat obesity. Likewise, a KD is currently explored as a supporting element in the treatment of obesity-associated metabolic disorders and certain forms of cancer. Here, we discuss the metabolic and biochemical mechanisms at play during the shift of metabolism to fatty acids and fatty acid-derived ketone bodies as main fuel molecules, in the substitution of carbohydrates, in ketogenic nutrition. Different sources of ketone bodies and KDs as alternatives to glucose and carbohydrates as main energy substrates are discussed, together with an attempt to weigh the benefits and risks posed by the chronic use of a KD in the context of weight loss, and also considering the molecular effects that ketone bodies exert on metabolism and on the endocrine system.

Mixed methods evaluation of a low-carbohydrate high-fat nutrition education program for women from underserved communities in South Africa

South Africa faces a dual burden of non-communicable diseases (NCDs) and communicable diseases, exacerbated by the high consumption of processed foods. The Eat Better South Africa (EBSA) program implements community-based low-carbohydrate, high-fat (LCHF) interventions to address these issues. This study evaluated the impact of EBSA's 6-week program on the metabolic health and well-being of 32 women from underserved communities. It assessed outcomes before, immediately after, and six months post-intervention (n = 21). Quantitative findings showed significant improvements in key health markers. After six months, participants experienced an average weight loss of 5.6 kg (+- 5.5), a BMI reduction of 2 kg/m2, and a waist circumference decrease of 6.6 cm. Blood pressure dropped by 10.7 mmHg on average, and fasting glucose levels decreased significantly. Reductions were also observed in triglycerides and HbA1c, indicating better glycemic control. Liver function markers (GGT, ALT) and inflammation markers (CRP) improved as well. Qualitative analysis highlighted several key themes: participants were motivated by a desire to improve their health and lose weight but faced challenges such as social pressures, community violence, and scepticism about the diet's affordability and sustainability. Despite these barriers, positive experiences like increased energy and better hunger control were reported. Participants expressed the need for ongoing support to maintain these changes, both from the program and from their community. These findings suggest that LCHF diets can effectively manage metabolic conditions, but long-term adherence is challenged by socio-economic factors. The study highlights the importance of community-based interventions and highlights the need for further research to develop sustainable health strategies in low-income settings.

Effectiveness of low-fat diet on the levels of insulin-like growth factor-1 and insulin-like growth factor binding proteins: a systematic review and meta-analysis of randomized controlled clinical trials

BACKGROUND

Previous researches on the effect of low-fat diet (LF) on insulin-like growth factor-1 (IGF-1), and its binding proteins (IGFBPs) did not reach a consensus result, and there is no study summarizing these findings. Thus, this systematic review and meta-analysis of randomized control trials (RCTs) was performed to pool available evidence and answer the question whether dietary fat can affect IGF-1 and IGFBPs or not.

METHODS

PubMed, Scopus, ISI Web of Science, Google, Google scholar, ProQuest, and the Cochrane Library were searched without language restrictions until July 2, 2024 to retrieve related studies. Weighted mean difference and the corresponding variance were considered as the effect size. Standard tools were applied to assess the quality of the studies and evidence.

RESULTS

Pooling data of the eligible studies showed no significant effect of LF diet on IGF-1 (six studies; participants = 1029.; pooled mean = 1.63 ng/ml, 95% CI= [-1.34, 4.59], P = 0.28, I2 = 0.00%), and IGFBP-3 (five studies; participants = 969; pooled mean = 65.24 ng/ml, 95% CI= [-169.53, 300.00], P = 0.59, I2 = 0.0%). The results of subgroup analysis for IGF-1 and IGFBP-3 also demonstrated no significant findings. For IGFBP-1, available evidence is insufficient since only two studies have been performed yet and their results are contradictory.

CONCLUSIONS

This study indicated no significant effect of LF diet on IGF-1, and IGFBP-3 concentrations. Low certainty of evidence indicates that available evidence cannot support to draw a firm conclusion and future researches may change the estimates.

Effects of Human Milk Oligosaccharide 2'-Fucosyllactose Ingestion on Weight Loss and Markers of Health

BACKGROUND

2'-Fucosyllactose (2'-FL) is an oligosaccharide contained in human milk and possesses prebiotic and anti-inflammatory effects, which may alleviate skeletal muscle atrophy under caloric restriction. This study evaluated the impacts of 12 weeks of 2'-FL supplementation in conjunction with exercise (10,000 steps/day, 5 days/week) and energy-reduced (-300 kcals/day) dietary interventions on changes in body composition and health-related biomarkers.

METHODS

A total of 41 overweight and sedentary female and male participants (38.0 ± 13 years, 90.1 ± 15 kg, 31.6 ± 6.6 kg/m2, 36.9 ± 7% fat) took part in a randomized, double-blind, and placebo-controlled study. The participants underwent baseline assessments and were then assigned to ingest 3 g/day of a placebo (PLA) or Momstamin 2'-F while initiating the exercise and weight-loss program. Follow-up tests were performed after 6 and 12 weeks. Data were analyzed using general linear model statistics with repeated measures and mean changes from baseline values with 95% confidence intervals (CIs).

RESULTS

No group × time × sex interaction effects were observed, so group × time effects are reported. Participants in both groups saw comparable reductions in weight. However, those with 2'-FL demonstrated a significantly greater reduction in the percentage of body fat and less loss of the fat-free mass. Additionally, there was evidence that 2'-FL supplementation promoted more favorable changes in resting fat oxidation, peak aerobic capacity, IL-4, and platelet aggregation, with some minimal effects on the fermentation of short-chain fatty acids and monosaccharides in fecal samples. Moreover, participants' perceptions regarding some aspects of the functional capacity and ratings of the quality of life were improved, and the supplementation protocol was well tolerated, although a small, but significant, decrease in BMC was observed.

CONCLUSIONS

The results support contentions that dietary supplementation of 2'-FL (3 g/d) can promote fat loss and improve exercise- and diet-related markers of health and fitness in overweight sedentary individuals initiating an exercise and weight-loss program. Further research is needed to explore the potential health benefits of 2'-FL supplementation in both healthy and elderly individuals (Registered clinical trial #NCT06547801).

Association of low carbohydrate diet score with the risk of type 2 diabetes in an Australian population: A longitudinal study

AIMS

We aimed to assess the association of a low carbohydrate diet score (LCD) with the incidence of type 2 diabetes (T2D) using Melbourne Collaborative Cohort Study (MCCS) data.

METHODS

Between 1990 and 1994, the MCCS recruited 41,513 people aged 40-69 years. The first and second follow-ups were conducted in 1995-1998 and 2003-2007, respectively. We analyzed data from 39,185 participants. LCD score was calculated at baseline as the percentage of energy from carbohydrate, fat, and protein. The higher the score the less percentage of carbohydrates contributed to energy intake. The association of LCD quintiles with the incidence of diabetes was assessed using modified Poisson regression, adjusted for lifestyle, obesity, socioeconomic and other confounders. Mediation of the association by adiposity (BMI) was assessed.

RESULTS

LCD was positively associated with diabetes risk. Higher LCD score (p for trend = 0.001) was associated with increased risk of T2D. Quintile 5 (38 % energy from carbohydrates) versus quintile 1 (55 % energy from carbohydrates) showed a 20 % increased diabetes risk (incidence risk ratio (IRR) = 1.20 (95 % CI: 1.05-1.37)). A further adjustment for BMI (Body Mass Index) and WHR (Waist-to-Hip-Ratio) eliminated the association. Mediation analysis demonstrated that BMI mediated 76 % of the LCD & diabetes association.

CONCLUSIONS

Consuming a low carbohydrate diet, reflected as a high LCD score, may increase the risk of T2D which is largely explained by obesity. Results highlight the need for further studies, including clinical trials investigating the effects of a low carbohydrate diet in T2D.

Obesity, Dietary Patterns, and Hormonal Balance Modulation: Gender-Specific Impacts

Understanding the intricate relationship between nutrition, hormonal balance, and gender-specific factors is crucial for developing targeted interventions to mitigate obesity-related endocrine disruptions and improve metabolic health. This narrative review examines the impact of various dietary patterns on hormonal regulation in both men and women, focusing on their effects on hormonal balance and metabolic health in the context of obesity. Calorie restriction, the Western diet, high-fat diets, low-CHO diets, plant-based diets, and the Mediterranean diet are analyzed in relation to their influence on obesity-related endocrine disruptions and metabolic health. Future research directions include investigating the specific mechanisms underlying dietary influences on hormonal regulation, addressing the gender-specific metabolic differences and body fat distribution, and exploring the dietary needs of individuals undergoing gender transition. Personalized dietary interventions tailored to individual metabolic and hormonal profiles are essential for optimizing health outcomes across the gender spectrum. By integrating gender-specific considerations into dietary recommendations, healthcare professionals can better support individuals in achieving optimal metabolic health and hormonal balance.

The Significant Impact of High-Fat, Low-Carbohydrate Ketogenic Diet on Serum Lipid Profile and Atherosclerotic Cardiovascular Disease Risk in Overweight and Obese Adults

Background and objectives Overweight and obesity are becoming more commonplace globally. The ketogenic diet (KD), also known as the high-fat, low-carbohydrate diet, has become increasingly popular in recent years as a means to lose weight quickly. This present study aims to examine the clinical effects of ketogenic diets in individuals who are obese or overweight by evaluating or assessing variations in metabolic parameters associated with lipid control, the risk of atherosclerotic cardiovascular disease, and other kidney risk indicators. Methods and subjects This observational case-control research involved 250 individuals in total and was conducted from May 2023 to January 2024. Of these, 158 were on a ketogenic diet, and 92 adults not following any type of diet were chosen to serve as controls. The biochemistry parameters of the kidney function test and lipid profile were measured for the two comparing groups. Data were analyzed for statistical significance using the Student t-test, Mann-Whitney U test, and one-way analysis of variance (ANOVA), followed by a post hoc test (least significant difference (LSD)). Chi-square tests were employed in the analysis to compare proportions. Results Out of 250 participants, there was a 20-80 age range, with their median age being 40 years old. The two comparing groups' lipid profiles were very different from one another; the cardiovascular risk (triglyceride (TG)/high-density lipoprotein (HDL)), total cholesterol, low-density lipoprotein (LDL), and triglyceride levels were all greater in the KD group when compared to the non-KD group. The mean LDL cholesterol (LDL-C) of the normal-weight participants was 56 mg/dL (p=0.079). Thereafter, it experienced a significant rise to 97.58 mg/dL and 108.2 mg/dL in those individuals who were overweight and obese, respectively (p<0.020). Conclusions As obesity rates in the populace keep rising, dietary fads such as the ketogenic diet are gaining traction. Although they could help with weight loss, this study had a notable observation of severe hypercholesterolemia and increased risk of atherosclerotic cardiovascular disease among the ketogenic diet participants. Additional research is necessary to ascertain if a ketogenic diet can be sustained over the long term and how it affects endpoints that are more clinically significant, such as morbidity and mortality due to obesity.

Towards a conceptual framework for the prevention of gambling-related harms: Findings from a scoping review

The global gambling sector has grown significantly over recent years due to liberal deregulation and digital transformation. Likewise, concerns around gambling-related harms-experienced by individuals, their families, their local communities or societies-have also developed, with growing calls that they should be addressed by a public health approach. A public health approach towards gambling-related harms requires a multifaceted strategy, comprising initiatives promoting health protection, harm minimization and health surveillance across different strata of society. However, there is little research exploring how a public health approach to gambling-related harms can learn from similar approaches to other potentially harmful but legal sectors such as the alcohol sector, the tobacco sector, and the high in fat, salt and sugar product sector. Therefore, this paper presents a conceptual framework that was developed following a scoping review of public health approaches towards the above sectors. Specifically, we synthesize strategies from each sector to develop an overarching set of public health goals and strategies which-when interlinked and incorporated with a socio-ecological model-can be deployed by a range of stakeholders, including academics and treatment providers, to minimise gambling-related harms. We demonstrate the significance of the conceptual framework by highlighting its use in mapping initiatives as well as unifying stakeholders towards the minimization of gambling-related harms, and the protection of communities and societies alike.

Modelling remission from overweight type 2 diabetes reveals how altering advice may counter relapse

The development or remission of diet-induced overweight type 2 diabetes involves many biological changes which occur over very different timescales. Remission, defined by HbA1c<6.5%, or fasting plasma glucose concentration G<126 mg/dl, may be achieved rapidly by following weight loss guidelines. However, remission is often short-term, followed by relapse. Mathematical modelling provides a way of investigating a typical situation, in which patients are advised to lose weight and then maintain fat mass, a slow variable. Remission followed by relapse, in a modelling sense, is equivalent to changing from a remission trajectory with steady state G<126 mg/dl, to a relapse trajectory with steady state G≥126 mg/dl. Modelling predicts that a trajectory which maintains weight will be a relapse trajectory, if the fat mass chosen is too high, the threshold being dependent on the lipid to carbohydrate ratio of the diet. Modelling takes into account the effects of hepatic and pancreatic lipid on hepatic insulin sensitivity and β-cell function, respectively. This study leads to the suggestion that type 2 diabetes remission guidelines be given in terms of model parameters, not variables; that is, the patient should adhere to a given nutrition and exercise plan, rather than achieve a certain subset of variable values. The model predicts that calorie restriction, not weight loss, initiates remission from type 2 diabetes; and that advice of the form 'adhere to the diet and exercise plan' rather than 'achieve a certain weight loss' may help counter relapse.

Dietary management of dyslipidemia

The rising burden of cardiovascular disease (CVD) has made the achievement of optimal lipoprotein levels a major public health priority. As nearly a fifth of global mortality is associated with dietary factors, and recommendations have been mired in controversy, a fresh look on the available data is attempted. Well established concepts regarding nutrition and cardiometabolic health, role of macronutrients, calories, and controversial foods are discussed followed by recommendations in the Indian context. A healthy dietary pattern rather than individual foods or nutrients is emphasized, and this is generally plant based with optional consumption of dairy, eggs, and meats within the suggested limits. Suggestions/recommendations are given for consumption of individual foods, remembering that choosing appropriate replacement foods is as important as restricting unhealthy foods.

Effectiveness of high-fat and high-carbohydrate diets on body composition and maximal strength after 15 weeks of resistance training

PURPOSE

The aim of this study was to compare High Carbohydrates Low Fat (HCLF) and Low Carbohydrate High Fat (LCHF) diets in terms of changes in body composition and maximal strength.

PATIENTS/METHODS

The study involved 48 men aged 25 ​± ​2.5, divided into two groups, one of which (n ​= ​23) was following the LCHF diet and the other (n ​= ​25) the HCLF diet. Both groups performed the same resistance training protocol for 15 weeks. Maximal strength in squat, bench press and deadlift was assessed pre- and post-intervention. Measurements of selected body circumferences and tissue parameters were made using the multifunctional, multi-frequency, direct bioelectric impedance InBody 770 analyzer from InBody Co., Ltd (Cerritos, California, USA). The team with the necessary qualifications and experience in research performed all the measurements and maintained participants' oversight throughout the entire length of the study.

RESULTS

Both nutritional approaches were effective in terms of reducing body fat mass. The HCLF group achieved greater skeletal muscle hypertrophy. Significant decreases in body circumferences, especially in the abdominal area, were observed for both dietary approaches. Maximal strength significantly increased in the HCLF group and decreased in the LCHF group.

CONCLUSION

Holistic analysis of the results led to the conclusion that both dietary approaches may elicit positive adaptations in body composition. The two approaches constitute useful alternatives for both recreational exercisers and physique athletes with body composition goals.

Effect of carbohydrate restriction on body weight in overweight and obese adults: a systematic review and dose-response meta-analysis of 110 randomized controlled trials

Introduction

Carbohydrate-restricted diets are one of the most effective dietary interventions for weight loss. However, the optimum carbohydrate intake for implementing the most effective weight-loss interventions is still being discussed. We aimed to determine the optimum carbohydrate intake for short- and long-term weight loss in adults with overweight and obesity.

Methods

We searched PubMed, Scopus, Web of Science, and CENTRAL from inception to May 2021 for randomized controlled trials examining the effect of a carbohydrate-restricted diet (≤45% of energy intake) as compared to a control diet (carbohydrate intake >45% of energy intake) on body weight in adults with overweight/obesity. A random-effects dose-response meta-analysis was conducted to calculate the mean difference for each 10% decrease in carbohydrate intake at the 6-month follow-up (1 to 6 months), 12-month follow-up (6 to 12 months), and follow-up longer than 12 months. The shape of the dose-dependent effects was also evaluated. The certainty of the evidence was rated using the GRADE approach. The minimal clinically important difference (MCID) threshold was defined as 5% weight loss (equal to 4.39 kg).

Results

A total of 110 trials were selected for the present meta-analysis. In the linear dose-response meta-analysis, each 10% decrease in carbohydrate intake reduced body weight by 0.64 kg (95% CI: -0.79 to -0.49; n = 101 trials with 4,135 participants, high-certainty evidence) at the 6-month follow-up and by 1.15 kg (95% CI: -1.61 to -0.69; 42 trials with 2,657 participants, moderate-certainty evidence) at the 12-month follow-up. Non-linear dose-response meta-analyses indicated a monotonic reduction in body weight with the decrease in carbohydrate intake, with the greatest reduction at 5% at the 6-month follow-up (mean difference 5%: -3.96 kg, 95% CI: -4.92 to -3.00) and 10% at the 12-month follow-up (mean difference 10%: -6.26 kg, 95% CI: -10.42 to -2.10). At follow-up longer than 12 months, dose-response analyses suggested a non-linear effect, wherein carbohydrate intakes higher than 40% and lower than 30% were not effective for weight loss.

Discussion

Carbohydrate restriction is an effective dietary strategy for important weight loss in adults with overweight and obesity. At 6-month and 12-month follow-ups, body weight decreased proportionally, more than the MCID threshold, along with the decrease in carbohydrate intake. At follow-up longer than 12 months, there was a non-linear effect, with the greatest reduction at 30% carbohydrate intake.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42022315042.

Association between dietary protein intake, diet quality and diversity, and obesity among women of reproductive age in Kersa, Ethiopia

Introduction

In Ethiopia, there is limited evidence on the effect of dietary protein intake on women's body mass index. Therefore, this study investigated the association between dietary protein intake, diet quality, and overweight and obesity.

Methods

A cross-sectional study was conducted among 897 women of reproductive age. Food frequency questionnaires were used to assess 7-day dietary intake. It was converted into protein and other macro-nutrient intakes, Minimum Dietary Diversity for Women, and Global Dietary Quality Score. Body Mass Index (BMI) of overweight & obese women were defined as ≥25 kg/m2. An adjusted odds ratio with a 95% confidence interval (in a multivariate logistic regression model) was used to determine the strength of the association between BMI and dietary protein intake, adjusting for potential confounders.

Results

The median dietary protein intake was 41.3 (32.9, 52.6) grams/day or 0.8 (0.6, 1.0) grams/kilogram of body weight/day. The prevalence of overweight and obesity was 7.5% (n = 67). Only 220 (24.5%) women could meet the recommended minimum dietary diversity of five or more food groups out of 10 per day. Furthermore, only 255 (28.4%) women were found to have a low risk for nutrient adequacy. Interestingly, women who consumed moderate dietary protein had a significantly lower likelihood of being overweight or obese, with AOR of 0.21 (95% CI 0.10-0.48). Similarly, those who consumed a high amount of protein had even lower odds, with AOR of 0.03 (95% CI 0.01-0.14), compared to those who consumed a low amount of dietary protein. Age of 40-49 years (AOR = 3.33, 95% CI 1.24-8.95) compared to 18-29 years, non-farmers (AOR = 3.21, 95% CI 1.55-6.62), higher consumption of food from unhealthy groups (AOR = 1.30, 95% CI 1.05-1.61), and high fat intake (AOR = 1.06, 95% CI 1.04-1.09) were associated with overweight and obesity.

Conclusions and recommendations

The study indicated an inverse relationship between BMI and dietary protein intake. It also revealed that women who consumed foods from unhealthy or unhealthy when consumed in excessive amounts were more likely to be overweight or obese. Increasing dietary protein consumption can help reproductive-age women reduce the odds of obesity and overweight. Furthermore, community-based educational programs, policy changes, and healthcare services can support this effort.

Reply to Najjar, R.S. Comment on "Dyńka et al. The Ketogenic Diet and Cardiovascular Diseases. Nutrients 2023, 15, 3368"

We thank Dr. Najjar for his interest [...].

Overall, plant-based, or animal-based low carbohydrate diets and all-cause and cause-specific mortality: A systematic review and dose-response meta-analysis of prospective cohort studies

INTRODUCTION

In this study, we sought to summarize the associations between overall, plant-, and animal-based low carbohydrate diet (LCD) scores and the risk of all-cause, cardiovascular disease (CVD), and cancer mortality from prospective cohort studies.

METHODS

We searched PubMed, Scopus, and Web of Science up to January 2022. We included prospective cohort studies that investigated the relationship between LCD-score and risk of overall, CVD, or cancer mortality. Two investigators assessed the studies for eligibility and extracted the data. Summary hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using a random-effects model.

RESULTS

Ten studies, with 421022 participants, were included in the analysis. In the high-versus-low meta-analysis, overall (HR:1.05,95%CI:0.97, 1.13, I2 =72.0%) and animal-based LCD-scores (HR: 1.08, 95% CI: 0.97-1.21; I2 = 88.0%) were not associated with all-cause mortality, but plant-based LCD-score was associated with a risk reduction (HR:0.87, 95%CI:0.78,0.97; I2 = 88.4%). CVD mortality was not associated with overall, plant-, or animal-based LCD-scores. Overall (HR:1.14, 95%CI:1.05,1.24; I2 = 37.4%) and animal-based LCD scores (HR:1.16,95%CI:1.02,1.31; I2 = 73.7%) were associated with a higher risk of cancer mortality, while plant-based LCD-score was not. A U-shaped relationship was revealed between overall LCD-score and all-cause and CVD mortality. The shape of relationship between LCD and cancer mortality was a linear dose-response.

CONCLUSION

In conclusion, diets with a moderate carbohydrate content were associated with the lowest risk of all-cause and CVD mortality. If the sources of macronutrients that replaced carbohydrates were plant-based, the risk of all-cause mortality was reduced linearly with lower carbohydrate content. The risk of cancer mortality increased linearly with the increase in carbohydrate content. Considering the low certainty of evidence, more robust prospective cohort studies are suggested.

Short- and long-term effects of very low- and low-calorie ketogenic diets on metabolism and cardiometabolic risk factors: a narrative review

Worldwide obesity and cardiovascular diseases have encouraged the adoption of new and efficient dietary strategies. Among various proposed diets, ketogenic diets, both the very-low-calorie ketogenic diet (VLCKD) and the low-calorie ketogenic diet (LCKD), have been suggested in recent years as an effective nutritional approach for obesity management. The VLCKD and the LCKD are characterized by a low carbohydrate content (<50 g/day), 1-1.5 g of protein/kg of ideal body weight, less than 20-30 g of lipids, and a daily intake of about 800 calories for VLCKD and about 1200-1400 calories for LCKD. The purpose of our narrative review is to offer an overview of the most impactful studies in the scientific literature regarding VLCKD and LCKD to discuss their short- and long-term effects (less than 12 months and more than 12 months respectively) on weight loss, metabolic and cardiovascular aspects. Articles we focused on were cohort studies, case-control studies, cross-sectional studies, randomized controlled trials, and meta-analyses. Results indicate that VLCKD and LCKD could be helpful to ameliorate metabolic and cardiovascular risk factors such as weight loss, glucose, and cholesterol levels, both in the short and long term. Further research in this area may include more randomized controlled trials to gather more data.

The Relationship between Oral Health-Related Quality of Life and Body Mass Index in an Older Population from Southern Italy: The Salus in Apulia Study

BACKGROUND

The assessment of oral health-related quality of life (OHRQoL) evaluated the impact of an individual's oral health on the patient's physical and psychosocial status. We evaluated the association between subjective OHRQoL, measured with the Oral Health Impact Profile-14 (OHIP-14) questionnaire, and unfavorable body mass index (BMI) (i.e., too high or too low) in a large population-based study on older adults from Southern Italy. Moreover, we assessed which of the seven OHIP-14 domains was the most strongly associated with an unfavorable BMI.

METHODS

We used data on a subpopulation of the Salus in Apulia Study, including 216 older adults. BMI < 18.4 kg/m2 and >30 kg/m2 were classified as unfavorable, while values between 18.5 and 30 kg/m2 were classified as ideal.

RESULTS

A higher OHIP-14 total score increased the risk of an unfavorable BMI (odds ratio (OR): 1.08, 95% confidence interval (CI): 1.01-1.15). In the model adjusted for age, sex, education, hypertension, carbohydrate consumption, and alcohol consumption, this finding was confirmed with a higher OHIP-14 total score increasing the risk of an unfavorable BMI (OR: 1.10, 95% CI: 1.01-1.22), and higher age linked to a decreased risk of an unfavorable BMI (OR: 0.89, 95% CI: 0.82-0.97). In a random forest regression model, the most important predictive domains/sub-scales of OHIP-14 in the mean decrease in the Gini coefficient for unfavorable BMI were, in order of decreasing importance, physical pain, functional limitation, psychological discomfort, physical disability, social disability, psychological disability, and handicap.

CONCLUSIONS

In older age, negative OHRQoL, particularly linked to the physical pain domain, increased the risk of being underweight or overweight and obesity.

Manchester Intermittent and Daily diet Type 1 Diabetes App Study (MIDDAS-Type 1): protocol for a randomised feasibility trial of an intermittent and continuous low-energy diet in patients with type 1 diabetes and overweight and obesity

INTRODUCTION

Rising levels of overweight and obesity among people with type 1 diabetes (T1D) contribute to insulin resistance, dyslipidaemia, retinopathy, cardiometabolic complications and psychological morbidity. Continuous low-energy diets (CLED) providing approximately 800 kcal (3347 kJ)/day can produce significant weight loss in type 2 diabetes, and intermittent low-energy diets (ILED) may be an alternative. The Manchester Intermittent and Daily diet Type 1 Diabetes App Study (MIDDAS-Type 1) aims to assess the safety, acceptability and feasibility of remotely delivered ILED and CLED programmes for people with T1D and overweight and obesity.

METHODS AND ANALYSIS

Twelve participants with T1D and body mass index ≥27.5 kg/m² (≥25 kg/m² in high-risk ethnic minorities) recruited from an National Health Service (NHS) trust and research register in England will be randomised to a remotely delivered CLED (n=6) or ILED (n=6) for 12 weeks. The CLED includes a daily Optifast 850 kcal (3556 kJ) 75 g carbohydrate formula diet. The ILED includes 2 days/week of Optifast and 5 days of a portion-controlled Mediterranean diet (170-250 g carbohydrate/day). Both groups will receive matched high-frequency remote support from a dietitian, nurse and psychologist via telephone and/or the Oviva app. The primary outcome will assess safety (occurrence of severe hypoglycaemia, ketonaemia, ketoacidosis and time above and below target blood glucose). Secondary outcomes include study uptake, retention, dietary adherence, acceptability, intervention delivery fidelity and potential efficacy in relation to change in weight, insulin requirements, glycated haemoglobin, lipids, insulin resistance (estimated glucose disposal rate) and quality of life. Participants will be invited for optional repeat measurements at 52 weeks.

ETHICS AND DISSEMINATION

The trial protocol (V4.0/08.06.2022) was granted ethical approval by Cambridge East Research Ethics Committee (Ref: 21/EE/0014). The study will inform progression to a full-scale randomised controlled trial to test the efficacy of these programmes for patients with T1D and overweight and obesity.

TRIAL REGISTRATION NUMBER

NCT04674384; Pre-results.

The effect of dietary carbohydrate and calorie restriction on weight and metabolic health in overweight/obese individuals: a multi-center randomized controlled trial

BACKGROUND

Both low-carbohydrate (LC) and calorie-restricted (CR) diets have been shown to have metabolic benefits. However, the two regimens have yet to be thoroughly compared. We conducted a 12-week randomized trial to compare the effects of these diets separately and in combination on both weight loss and metabolic risk factors in overweight/obese individuals.

METHODS

A total of 302 participants were randomized to LC diet (n = 76), CR diet (n = 75), LC + CR diet (n = 76), or normal control (NC) diet (n = 75) using a computer-based random number generator. The primary outcome was the change in body mass index (BMI). The secondary outcomes included body weight, waist circumference, waist-to-hip ratio, body fat, and metabolic risk factors. All participants attended health education sessions during the trial.

RESULTS

A total of 298 participants were analyzed. BMI change over 12 weeks was - 0.6 (95% CI, - 0.8 to - 0.3) kg/m2 in NC, - 1.3 (95% CI, - 1.5 to - 1.1) kg/m2 in CR, - 2.3 (95% CI, - 2.6 to - 2.1) kg/m2 in LC, and - 2.9 (95% CI, - 3.2 to - 2.6) kg/m2 in LC + CR. LC + CR diet was more effective than LC or CR diet alone at reducing BMI (P = 0.001 and P < 0.001, respectively). Furthermore, compared with the CR diet, the LC + CR diet and LC diet further reduced body weight, waist circumference, and body fat. Serum triglycerides were significantly reduced in the LC + CR diet group compared with the LC or CR diet alone. Plasma glucose, homeostasis model assessment of insulin resistance, and cholesterol concentrations (total, LDL, and HDL) did not change significantly between the groups during the 12-week intervention.

CONCLUSIONS

The reduction of carbohydrate intake without restricting caloric intake is more potent to achieve weight loss over 12 weeks when compared to a calorie-restricted diet in overweight/obese adults. The combination of restricting carbohydrate and total calorie intake may augment the beneficial effects of reducing BMI, body weight, and metabolic risk factors among overweight/obese individuals.

TRIAL REGISTRATION

The study was approved by the institutional review board of Zhujiang Hospital of Southern Medical University and registered at the China Clinical Trial Registration Center (registration number: ChiCTR1800015156).

Is Type 2 Diabetes Mellitus a Behavioural Disorder? An Evidence Review for Type 2 Diabetes Mellitus Prevention and Remission through Lifestyle Modification

The prevalence of type 2 diabetes mellitus (T2DM) is steadily rising worldwide due to an increasingly sedentary lifestyle combined with unhealthy food habits. Currently, the burden of diabetes on healthcare systems is unprecedented and rising daily. Several observational studies and randomized controlled trials provide clinical evidence that T2DM remission is possible by adopting dietary interventions and a strict exercise training protocol. Notably, these studies provide ample evidence for remission in patients with T2DM or for prevention in those with risk factors for the disease through various non-pharmacological behavioural interventions. In this article, we present two clinical cases of individuals who showed remission from T2DM/prediabetes via behavioural changes, especially through the adoption of a low-energy diet and exercise. We also discuss the recent advances in T2DM and obesity research, focusing on nutritional interventions and exercise and their benefits for weight loss, improved metabolic profile, enhanced glycaemic control and remission of diabetes.

Very Low-Calorie Ketogenic Diet (VLCKD) as Pre-Operative First-Line Dietary Therapy in Patients with Obesity Who Are Candidates for Bariatric Surgery

Bariatric surgery is currently the most effective method for achieving long-term weight loss and reducing the risk of comorbidities and mortality in individuals with severe obesity. The pre-operative diet is an important factor in determining patients' suitability for surgery, as well as their post-operative outcomes and success in achieving weight loss. Therefore, the nutritional management of bariatric patients requires specialized expertise. Very low-calorie diets and intragastric balloon placement have already been studied and shown to be effective in promoting pre-operative weight loss. In addition, the very low-calorie ketogenic diet has a well-established role in the treatment of obesity and type 2 diabetes mellitus, but its potential role as a pre-operative dietary treatment prior to bariatric surgery has received less attention. Thus, this article will provide a brief overview of the current evidence on the very low-calorie ketogenic diet as a pre-operative dietary treatment in patients with obesity who are candidates for bariatric surgery.

Mediterranean diet in the management and prevention of obesity

The current pandemic of obesity represents a major global public health problem, mainly due to its association with chronic non-communicable disabling conditions and with increased mortality. Population aging increases the chances of non-communicable chronic diseases allowing a longer exposure to risk factors for these disabling conditions. Obesity is a major risk factor contributing to pathological aging. Numerous epidemiological studies have shown that the risk of death due to cardiovascular disease and cancer increases progressively as overweight and obesity rise. Nutrition research is now focused on the effects of combinations of foods in dietary patterns instead of those of single nutrients or foods. The dietary model with the largest body of evidence of health benefit is that traditionally followed by inhabitants of some Mediterranean countries. There is evidence confirming the inverse association of adhering to Mediterranean diet with overweight and obesity. Four meta-analyses of randomized controlled trials, including up to 16 trials, have shown a greater reduction of body weight and BMI with MedDiet compared to other diets, while a meta-analysis of 7 prospective cohort studies, found a reduced risk of becoming obese and gaining weight over time associated with a higher adherence to MedDiet. This narrative review examines studies reporting inverse associations of a higher adherence to the MedDiet with overweight/obesity and with age-associated chronic diseases related to obesity.

Prescribing diabetes nutrition therapy: a qualitative study of dietitians' experiences of carbohydrate restriction in Canada

BACKGROUND

Diabetes care has traditionally not included nutrition therapy using carbohydrate restriction, nor has carbohydrate restriction been taught to registered dietitians (RDs) to support patients living with diabetes choosing this dietary approach. We aimed to describe the experiences and views of RDs caring for patients using therapeutic carbohydrate-restricted diets (TCR), particularly metabolic conditions such as type 2 diabetes or prediabetes.

SUBJECTS/METHODS

A qualitative study design using free-text responses from an online needs assessment survey was employed. RDs who practised in Canada were invited (n=6640) and 274 completed the survey, with 45 respondents who regularly prescribed TCR to their patients providing open-text responses (2987 words), which were analysed using inductive thematic analysis.

RESULTS

We identified four themes characterising Canadian RDs' experiences around prescribing TCR: interpersonal context, personal experience/knowledge, regulatory environment and patient-centredness. While these themes often interacted, each impacted TCR prescription uniquely, with patient-centred care at the core of reported experiences of prescribing.

CONCLUSIONS

There exists a variety of experiences and perspectives related to prescribing of TCR among Canadian RDs caring for patients with diabetes, and all focus on the patient's needs, benefits and preferences. Prescribing TCR was often informed by the scientific literature yet also by RDs' experiential knowledge. Responses highlighted a desire for evidence-based educational materials and greater discussion within the diabetes nutrition community on this topic.

The effects of a low carbohydrate diet on erectile function and serum testosterone levels in hypogonadal men with metabolic syndrome: a randomized clinical trial

PURPOSE

Metabolic syndrome is a risk factor for several diseases. The relationship between metabolic syndrome and hypogonadism is well known. Our objetive is to assess whether a low carbohydrate diet can increase total serum testosterone and improve erectile function in hypogonadal men with metabolic syndrome.

METHODS

An open label randomized clinical trial was conducted comparing a low carbohydrate diet and controls, during three months, in hypogonadal men with metabolic syndrome. Anthropometric measurements were evaluated as well as total serum testosterone levels, and symptoms of hypogonadism, using the ADAM and AMS scores, and sexual function using IIEF-5 score.

RESULTS

Eighteen men were evaluated. Anthropometric measures were improved only in low carbohydrate diet group. The intervention group also had a statistically increase in IIEF-5 score and a significant reduction in AMS and ADAM scores (p < 0.001). The increase in serum total testosterone levels was statistically significant in the low carbohydrate group compared to the control group as well as calculated free testosterone (p < 0.001).

CONCLUSIONS

Low carbohydrate diet may increase serum levels of testosterone and improve erectile function in hypogonadal men with metabolic syndrome. However, larger studies are necessary to strongly prove the effectiveness of low carbohydrate diet in treating male hypogonadism.

The relationship between low-carbohydrate diet score, dietary insulin index and load with obesity in healthy adults

PURPOSE

Carbohydrate intake and insulinemic potential of diet are suggested to be correlated with the development of different chronic diseases. Considering the limited research on obesity, this study aimed to investigate the association of dietary insulin index (DII), dietary insulin load (DIL), and low-carbohydrate diet score (LCDS) with body weight and obesity in healthy adults.

METHODS

In this cross-sectional study, DII, DIL, and LCDS were calculated using relevant formulas based on dietary intakes obtained by a valid 168-item food frequency questionnaire, in 393 otherwise healthy adults of either normal-weight, overweight, or obese.

RESULTS

Individuals in the highest tertile of DIL and DII had respectively 73% (OR: 0.27, 95% CI 0.08-0.94, p = 0.049) and 50% (OR: 0.5, 95% CI 0.26-0.96, p = 0.038) lower odds of being overweight compared to the lowest tertile, after adjusting the effects of age, sex, and dietary energy intake. Participants in the highest tertile of DIL had 92% greater odds of being obese compared to the lowest tertile, but this association did not remain significant after adjusting the effect of energy intake. Individuals in the highest tertile of LCDS had about 2 times odds of being overweight compared with those in the lowest tertile (OR: 2.04, 95% CI 1.04-4.01, p = 0.049). There was no relationship between being obese and tertiles of LCDS.

CONCLUSION

Higher dietary carbohydrate intake and insulinemic potential of diet could not be considered independent dietary risk factors for overweight or obesity.

LEVEL OF EVIDENCE

Level III: evidence obtained from an observational study.

The Data Behind Popular Diets for Weight Loss

Both scientific evidence and popular diet trends have sought to identify the ideal diet for weight loss with strategies focused on either restricting carbohydrates or fat. While there is a strong physiologic rationale for either carbohydrate restriction or fat restriction to achieve a calorie deficit needed for weight loss, evidence from randomized controlled trials suggest either type of diet is effective for weight loss. The level of adherence, rather than macronutrient content, is the driver of successful weight loss.

Low fat diet versus low carbohydrate diet for management of non-alcohol fatty liver disease: A systematic review

Although there is a consensus on beneficial effects of a low calorie diet in management of non-alcoholic fatty liver disease, the optimal composition of diet has not yet been elucidated. The aim of this review is to summarize the results of current randomized controlled trials evaluating the effects of low fat diet (LFD) vs. low carbohydrate diet (LCD) on NAFLD. This is a systematic review of all the available data reported in published clinical trials up to February 2022. The methodological quality of eligible studies was assessed, and data were presented aiming specific standard measurements. A total of 15 clinical trial studies were included in this systematic review. There is an overall lack of consensus on which dietary intervention is the most beneficial for NAFLD patients. There is also an overall lack of consensus on the definition of the different restrictive diets and the percentage of macronutrient restriction recommended. It seems that low calorie diets, regardless of their fat and carbohydrate composition, are efficient for liver enzyme reduction. Both LCD and LFD have similar effects on liver enzymes change; however, this improvement tends to be more marked in LFD. All calorie restrictive dietary interventions are beneficial for reducing weight, liver fat content and liver enzymes in individuals with NAFLD. Low fat diets seem to be markedly successful in reducing transaminase levels. Further research is needed to explore diet intensity, duration and long-term outcome.

Ketones: potential to achieve brain energy rescue and sustain cognitive health during ageing

Alzheimer’s disease (AD) is the most common major neurocognitive disorder of ageing. Although largely ignored until about a decade ago, accumulating evidence suggests that deteriorating brain energy metabolism plays a key role in the development and/or progression of AD-associated cognitive decline. Brain glucose hypometabolism is a well-established biomarker in AD but was mostly assumed to be a consequence of neuronal dysfunction and death. However, its presence in cognitively asymptomatic populations at higher risk of AD strongly suggests that it is actually a pre-symptomatic component in the development of AD. The question then arises as to whether progressive AD-related cognitive decline could be prevented or slowed down by correcting or bypassing this progressive ‘brain energy gap’. In this review, we provide an overview of research on brain glucose and ketone metabolism in AD and its prodromal condition – mild cognitive impairment (MCI) – to provide a clearer basis for proposing keto-therapeutics as a strategy for brain energy rescue in AD. We also discuss studies using ketogenic interventions and their impact on plasma ketone levels, brain energetics and cognitive performance in MCI and AD. Given that exercise has several overlapping metabolic effects with ketones, we propose that in combination these two approaches might be synergistic for brain health during ageing. As cause-and-effect relationships between the different hallmarks of AD are emerging, further research efforts should focus on optimising the efficacy, acceptability and accessibility of keto-therapeutics in AD and populations at risk of AD.

Associations of Moderate Low-Carbohydrate Diets With Mortality Among Patients With Type 2 Diabetes: A Prospective Cohort Study

CONTEXT

A statement of context for the abstract was added in Objective as follows: Lower-carbohydrate-diet (LCD) has been reported to have beneficial effects on cardiovascular risk factor profile in general population. However, whether adherence to an LCD could benefit long-term survival among individuals with diabetes is unclear.

OBJECTIVE

This work aimed to investigate the associations of different types of lower-carbohydrate diets with mortality among individuals with type 2 diabetes (T2D).

METHODS

This prospective study included 5677 patients with T2D. The overall, unhealthy, and healthy lower-carbohydrate-diet (LCD) scores were calculated based on the percentage of energy from total and subtypes of carbohydrate, protein, and fat. Deaths were determined via linkage to the National Death Index records until December 31, 2015. Cox proportional hazards models were used to estimate the hazard ratios (HRs) and 95% CIs of mortality.

RESULTS

During a median of 6.3 years of follow-up (39 401 person-years), 1432 deaths were documented. After multivariable adjustment including lifestyle factors, diabetes duration, and glycated hemoglobin A1c, patients in the third quartile of overall LCD score had the lowest risk of mortality (HR: 0.65; 95% CI, 0.50-0.85), compared with the first quartile. The multivariable-adjusted HRs (95% CIs) of mortality across quartiles of healthy lower-carbohydrate-diet score were 1.00 (reference), 0.78 (0.64-0.96), 0.73 (0.58-0.91), and 0.74 (0.58-0.95) (Ptrend = .01). Isocalorically replacing 2% of energy from carbohydrates with plant-based protein or polyunsaturated fatty acids was associated with 23% to approximately 37% lower total mortality. Similar results were observed when analyses were stratified by age, sex, race/ethnicity, smoking status, body mass index, physical activity, and diabetes duration.

CONCLUSION

Healthy LCD score was significantly associated with a lower risk of mortality in adults with T2D. Adherence to a well-balanced moderate lower-carbohydrate diet that emphasizes healthy carbohydrates, plant-based protein, and polyunsaturated fat may prevent premature death among patients with T2D.

Reversal and Remission of T2DM - An Update for Practitioners

Over the past 50 years, many countries around the world have faced an unchecked pandemic of obesity and type 2 diabetes (T2DM). As best practice treatment of T2DM has done very little to check its growth, the pandemic of diabesity now threatens to make health-care systems economically more difficult for governments and individuals to manage within their budgets. The conventional view has been that T2DM is irreversible and progressive. However, in 2016, the World Health Organization (WHO) global report on diabetes added for the first time a section on diabetes reversal and acknowledged that it could be achieved through a number of therapeutic approaches. Many studies indicate that diabetes reversal, and possibly even long-term remission, is achievable, belying the conventional view. However, T2DM reversal is not yet a standardized area of practice and some questions remain about long-term outcomes. Diabetes reversal through diet is not articulated or discussed as a first-line target (or even goal) of treatment by any internationally recognized guidelines, which are mostly silent on the topic beyond encouraging lifestyle interventions in general. This review paper examines all the sustainable, practical, and scalable approaches to T2DM reversal, highlighting the evidence base, and serves as an interim update for practitioners looking to fill the practical knowledge gap on this topic in conventional diabetes guidelines.

Low-carbohydrate versus balanced-carbohydrate diets for reducing weight and cardiovascular risk

BACKGROUND

Debates on effective and safe diets for managing obesity in adults are ongoing. Low-carbohydrate weight-reducing diets (also known as 'low-carb diets') continue to be widely promoted, marketed and commercialised as being more effective for weight loss, and healthier, than 'balanced'-carbohydrate weight-reducing diets.

OBJECTIVES

To compare the effects of low-carbohydrate weight-reducing diets to weight-reducing diets with balanced ranges of carbohydrates, in relation to changes in weight and cardiovascular risk, in overweight and obese adults without and with type 2 diabetes mellitus (T2DM).

SEARCH METHODS

We searched MEDLINE (PubMed), Embase (Ovid), the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science Core Collection (Clarivate Analytics), ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) up to 25 June 2021, and screened reference lists of included trials and relevant systematic reviews. Language or publication restrictions were not applied.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in adults (18 years+) who were overweight or living with obesity, without or with T2DM, and without or with cardiovascular conditions or risk factors. Trials had to compare low-carbohydrate weight-reducing diets to balanced-carbohydrate (45% to 65% of total energy (TE)) weight-reducing diets, have a weight-reducing phase of 2 weeks or longer and be explicitly implemented for the primary purpose of reducing weight, with or without advice to restrict energy intake.  DATA COLLECTION AND ANALYSIS: Two review authors independently screened titles and abstracts and full-text articles to determine eligibility; and independently extracted data, assessed risk of bias using RoB 2 and assessed the certainty of the evidence using GRADE. We stratified analyses by participants without and with T2DM, and by diets with weight-reducing phases only and those with weight-reducing phases followed by weight-maintenance phases. Primary outcomes were change in body weight (kg) and the number of participants per group with weight loss of at least 5%, assessed at short- (three months to < 12 months) and long-term (≥ 12 months) follow-up.

MAIN RESULTS

We included 61 parallel-arm RCTs that randomised 6925 participants to either low-carbohydrate or balanced-carbohydrate weight-reducing diets. All trials were conducted in high-income countries except for one in China. Most participants (n = 5118 randomised) did not have T2DM. Mean baseline weight across trials was 95 kg (range 66 to 132 kg). Participants with T2DM were older (mean 57 years, range 50 to 65) than those without T2DM (mean 45 years, range 22 to 62). Most trials included men and women (42/61; 3/19 men only; 16/19 women only), and people without baseline cardiovascular conditions, risk factors or events (36/61). Mean baseline diastolic blood pressure (DBP) and low-density lipoprotein (LDL) cholesterol across trials were within normal ranges. The longest weight-reducing phase of diets was two years in participants without and with T2DM. Evidence from studies with weight-reducing phases followed by weight-maintenance phases was limited. Most trials investigated low-carbohydrate diets (> 50 g to 150 g per day or < 45% of TE; n = 42), followed by very low (≤ 50 g per day or < 10% of TE; n = 14), and then incremental increases from very low to low (n = 5). The most common diets compared were low-carbohydrate, balanced-fat (20 to 35% of TE) and high-protein (> 20% of TE) treatment diets versus control diets balanced for the three macronutrients (24/61). In most trials (45/61) the energy prescription or approach used to restrict energy intake was similar in both groups. We assessed the overall risk of bias of outcomes across trials as predominantly high, mostly from bias due to missing outcome data. Using GRADE, we assessed the certainty of evidence as moderate to very low across outcomes.  Participants without and with T2DM lost weight when following weight-reducing phases of both diets at the short (range: 12.2 to 0.33 kg) and long term (range: 13.1 to 1.7 kg).  In overweight and obese participants without T2DM: low-carbohydrate weight-reducing diets compared to balanced-carbohydrate weight-reducing diets (weight-reducing phases only) probably result in little to no difference in change in body weight over three to 8.5 months (mean difference (MD) -1.07 kg, (95% confidence interval (CI) -1.55 to -0.59, I2 = 51%, 3286 participants, 37 RCTs, moderate-certainty evidence) and over one to two years (MD -0.93 kg, 95% CI -1.81 to -0.04, I2 = 40%, 1805 participants, 14 RCTs, moderate-certainty evidence); as well as change in DBP and LDL cholesterol over one to two years. The evidence is very uncertain about whether there is a difference in the number of participants per group with weight loss of at least 5% at one year (risk ratio (RR) 1.11, 95% CI 0.94 to 1.31, I2 = 17%, 137 participants, 2 RCTs, very low-certainty evidence).  In overweight and obese participants with T2DM: low-carbohydrate weight-reducing diets compared to balanced-carbohydrate weight-reducing diets (weight-reducing phases only) probably result in little to no difference in change in body weight over three to six months (MD -1.26 kg, 95% CI -2.44 to -0.09, I2 = 47%, 1114 participants, 14 RCTs, moderate-certainty evidence) and over one to two years (MD -0.33 kg, 95% CI -2.13 to 1.46, I2 = 10%, 813 participants, 7 RCTs, moderate-certainty evidence); as well in change in DBP, HbA1c and LDL cholesterol over 1 to 2 years. The evidence is very uncertain about whether there is a difference in the number of participants per group with weight loss of at least 5% at one to two years (RR 0.90, 95% CI 0.68 to 1.20, I2 = 0%, 106 participants, 2 RCTs, very low-certainty evidence).  Evidence on participant-reported adverse effects was limited, and we could not draw any conclusions about these.  AUTHORS' CONCLUSIONS: There is probably little to no difference in weight reduction and changes in cardiovascular risk factors up to two years' follow-up, when overweight and obese participants without and with T2DM are randomised to either low-carbohydrate or balanced-carbohydrate weight-reducing diets.

Meal Timing and Macronutrient Composition Modulate Human Metabolism and Reward-Related Drive to Eat

The ‘time-of-day’ modifies the metabolic response to meals, but less data exist on the diurnal variations in the hedonic drive to eat. In the present paper, we evaluate the effects of meal timing and macronutrient composition on metabolic responses and the homeostatic vs. hedonic regulation of appetite. In study 1, 84 young, healthy adults completed an online computer-based task assessing the homeostatic and hedonic drive to eat in the morning and evening. In study 2, 24 healthy, young men received 2 identical (850 kcal each) meals in the morning (8:45 h) and evening (18:00 h), of 2 experimental conditions: (i) regular carbohydrate (CH) meals (regular-CH), and (ii) high carbohydrate (high-CH) meals, containing 50 and 80% of energy from CHs, respectively. Serial blood samples were obtained, and the postprandial feelings of hunger, satiety, wanting and liking were assessed. Study 1 revealed a higher hedonic drive to eat in the evening compared to the morning. Study 2 confirmed this diurnal pattern of hedonic appetite regulation and, moreover, showed increased glucose and insulin responses to the evening meal. Postprandial ghrelin and leptin as well as feelings of hunger and satiety were not different between the mealtimes nor between the macronutrient conditions. In line with this, the homeostatic drive to eat was neither affected by the mealtime nor macronutrient composition. Increased the hedonic drive to eat in the evening may represent a vulnerability to palatable food and, thus, energy overconsumption. Together with lower evening glucose tolerance, these findings reflect an adverse metabolic constellation at the end of the day, especially after the ingestion of CH-rich foods.

Impact of low-carbohydrate diet on serum levels of leptin and adiponectin levels: a systematic review and meta-analysis in adult

Background

Various studies have evaluated the effects of low-carbohydrate diet (LCD) on serum concentrations of adipokines. Although the association between LCD and serum levels of leptin and adiponectin has been studied extensively, the results were not consistent.

Objective

The purpose of this study was to systematically evaluate the effect of LCD on serum levels of leptin and adiponectin.

Design

Electronic databases were retrieved in PubMed, Embase, Scopus and Web of Science to search relevant publications. Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated by the random-effect model. Cochrane Q test and I² statistic were used to test heterogeneity. Subgroup analysis and meta-regression were applied to assess possible sources of heterogeneity.

Results

A total of thirty-five articles were included in final analysis. Meta-analysis results revealed no statistical association between LCD and adiponectin concentration (WMD: 0.32 ng/ml, 95% CI: - 0.02, 0.66, p=0.062). Subgroup analysis showed that LCD increased adiponectin concentration in subjects under 45 years old and in studies with long term duration intervention. Also, did not observe a significant effect from the LCD on serum concentration of leptin (WMD: - 0.77 ng/ml, 95% CI: -3.15, 1.61, P=0.409). Subgroup analysis did not show any new information. The results of this study did not support the evidence for the positive effects of LCD on serum leptin and adiponectin levels.

Dietary patterns associated with obesity outcomes in adults: an umbrella review of systematic reviews

OBJECTIVE

The aim of this umbrella review was to summarise the evidence from existing systematic reviews on the association between different dietary patterns (DP) and overweight or obesity outcomes in adults.

DESIGN

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and searched the MEDLINE, EMBASE, CINAHL, Cochrane, Scopus, and Web of Science for systematic reviews reporting on DP and weight gain or overweight/obesity outcomes.

RESULT

We identified 16 systematic reviews with 143 unique studies published between 2001 and 2019. Overall quality scores ranged from 4 to 10. Six reviews in 2/11 cohort and 6/19 cross-sectional studies reported (statistically significant) decreased OR for obesity (range: 0·53 to 0·73 and 0·35 to 0·88, respectively) associated with the Mediterranean diet. Five reviews in 5/15 cohort and 10/45 cross-sectional studies reported an inverse association between diet quality and weight gain or BMI (β range: -1·3 to -0·09). Two reviews in 1/3 cohort and 1/2 cross-sectional studies reported a decreased risk of obesity (OR = 0·76) and weight gain (OR = 0·26), respectively, with fruit and vegetable intake. Five reviews of mixed DP in 3/40 cross-sectional studies reported an increased prevalence of obesity (OR = 1·19) or abdominal obesity (OR range: 1·07 to 1·27) with the Korean diet pattern.

CONCLUSIONS

Our umbrella review confirms the hypothesis that Mediterranean-type DP reduce the risk of obesity in adults. Although population-specific evidence of effective interventions is needed, characteristics of Mediterranean-type DP are important considerations for national obesity prevention strategies.

Two of a Kind? Mapping the Psychopathological Space between Obesity with and without Binge Eating Disorder

(1) Background: Obesity (OB) is a frequent co-morbidity in Binge Eating Disorder (BED), suggesting that both conditions share phenotypical features along a spectrum of eating-related behaviors. However, the evidence is inconsistent. This study aimed to comprehensively compare OB-BED patients against OB individuals without BED and healthy, normal-weight controls in general psychopathological features, eating-related phenotypes, and early life experiences. (2) Methods: OB-BED patients (n = 37), OB individuals (n = 50), and controls (n = 44) completed a battery of standardized questionnaires. Responses were analyzed using univariate comparisons and dimensionality reduction techniques (linear discriminant analysis, LDA). (3) Results: OB-BED patients showed the highest scores across assessments (e.g., depression, emotional and stress eating, food cravings, food addiction). OB-BED patients did not differ from OB individuals in terms of childhood traumatization or attachment styles. The LDA revealed a two-dimensional solution that distinguished controls from OB and OB-BED in terms of increasing problematic eating behaviors and attitudes, depression, and childhood adversities, as well as OB-BED from OB groups in terms of emotional eating tendencies and self-regulation impairments. (4) Conclusions: Findings support the idea of a shared spectrum of eating-related disorders but also highlight important distinctions relevant to identifying and treating BED in obese patients.

Which Diets Are Effective in Reducing Cardiovascular and Cancer Risk in Women with Obesity? An Integrative Review

Women are more affected by obesity than men which increases their risk of cancer and cardiovascular disease (CVD). Therefore, it is important to understand the effectiveness of different types of diet in the context of women's health. This review aims to summarize the scientific evidence on the effects of different types of diet for women with obesity and their impact on CVD and cancer risk. This review included epidemiological and clinical studies on adult women and different types of diets, such as the Mediterranean (MED) diet, the Traditional Brazilian Diet, the Dietary Approach to Stop Hypertension (DASH), intermittent fasting (IF), calorie (energy) restriction, food re-education, low-carbohydrate diet (LCD) and a very low-carbohydrate diet (VLCD). Our main findings showed that although LCDs, VLCD and IF are difficult to adhere to over an extended period, they can be good options for achieving improvements in body weight and cardiometabolic parameters. MED, DASH and the Traditional Brazilian Diet are based on natural foods and reduced processed foods. These diets have been associated with better women's health outcomes, including lower risk of CVD and cancer and the prevention and treatment of obesity.

Lower Dietary Intake of Plant Protein Is Associated with Genetic Risk of Diabetes-Related Traits in Urban Asian Indian Adults

The increasing prevalence of type 2 diabetes among South Asians is caused by a complex interplay between environmental and genetic factors. We aimed to examine the impact of dietary and genetic factors on metabolic traits in 1062 Asian Indians. Dietary assessment was performed using a validated semi-quantitative food frequency questionnaire. Seven single nucleotide polymorphisms (SNPs) from the Transcription factor 7-like 2 and fat mass and obesity-associated genes were used to construct two metabolic genetic risk scores (GRS): 7-SNP and 3-SNP GRSs. Both 7-SNP GRS and 3-SNP GRS were associated with a higher risk of T2D (p = 0.0000134 and 0.008, respectively). The 3-SNP GRS was associated with higher waist circumference (p = 0.010), fasting plasma glucose (FPG) (p = 0.002) and glycated haemoglobin (HbA1c) (p = 0.000066). There were significant interactions between 3-SNP GRS and protein intake (% of total energy intake) on FPG (Pinteraction = 0.011) and HbA1c (Pinteraction = 0.007), where among individuals with lower plant protein intake (<39 g/day) and those with >1 risk allele had higher FPG (p = 0.001) and HbA1c (p = 0.00006) than individuals with ≤1 risk allele. Our findings suggest that lower plant protein intake may be a contributor to the increased ethnic susceptibility to diabetes described in Asian Indians. Randomised clinical trials with increased plant protein in the diets of this population are needed to see whether the reduction of diabetes risk occurs in individuals with prediabetes.

Ketogenic Diet, Physical Activity, and Hypertension-A Narrative Review

Several studies link cardiovascular diseases (CVD) with unhealthy lifestyles (unhealthy dietary habits, alcohol consumption, smoking, and low levels of physical activity). Therefore, the strong need for CVD prevention may be pursued through an improved control of CVD risk factors (impaired lipid and glycemic profiles, high blood pressure, and obesity), which is achievable through an overall intervention aimed to favor a healthy lifestyle. Focusing on diet, different recommendations emphasize the need to increase or avoid consumption of entire classes of food, with only partly known and only partly foreseeable consequences on the overall level of health. In recent years, the ketogenic diet (KD) has been proposed to be an effective lifestyle intervention for metabolic syndrome, and although the beneficial effects on weight loss and glucose metabolism seems to be well established, the effects of a prolonged KD on the ability to perform different types of exercise and the influence of KD on blood pressure (BP) levels, both in normotensives and in hypertensives, are not so well understood. The objective of this review is to analyze, on the basis of current evidence, the relationship between KD, regular physical activity, and BP.

The effect of high-fat versus high-carb diet on body composition in strength-trained males

Low-fat, high-carb (LFHC) and low-carb, high-fat (LCHF) diets change body composition as a consequence of the reduction of body fat of overweight persons. The aim of this study is the assessment of the impact of LFHC and LCHF diets on body composition of men of a healthy body mass who do strength sports while maintaining the appropriate calorific value in a diet and protein intake. The research involved 55 men aged 19-35, with an average BMI of 24.01 ± 1.17 (min. 20.1, max. 26.1). The participants were divided into two groups following two interventional diets: high-fat diet or high-carb diet, for 12 weeks. The body composition of the participants was measured using bioimpedance. After the 12-week-long experiment based on the low-carbohydrate diet, a significant body mass reduction of 1.5% was observed. In the group, following the LFHC diet, the parameters did not significantly change. In the group following LCHF diet, the body fat reduction of 8.6% from 14 (6.7-19.8) kg to 12.7 (3.9-19.2) was reported (p = 0.01) (in the absolute value of 1.2 kg). However, also in the LFHC group, the body fat mass was significantly reduced, that is, by 1.5% (p = 0.01) (by 0.4 kg). Nevertheless, it is worth emphasizing that despite significant changes within the groups, these changes were not statistically significant between the groups. Diets with different carbohydrate and fat intake and the energy value covering the energy needs of men training strength sports have similar impact on changes in body composition.

Synopsis of the 2020 U.S. VA/DoD Clinical Practice Guideline for the Management of Adult Overweight and Obesity

INTRODUCTION

In May of 2020, the U.S. Veterans Health Administration (VHA) and Department of Defense (DoD) approved a new joint clinical practice guideline for assessing and managing patients who have overweight and obesity. This guideline is intended to give healthcare teams a framework by which to screen, evaluate, treat, and manage the individual needs and preferences of VA and DoD patients who may have either of these conditions. It can be accessed at https://www.healthquality.va.gov/guidelines/CD/obesity/.

MATERIALS AND METHODS

In January of 2019, the VA/DoD Evidence-Based Practice Work Group convened a joint VA/DoD guideline development effort that included clinical stakeholders and conformed to the Institute of Medicine's tenets for trustworthy clinical practice guidelines.

RESULTS

The guideline panel developed 12 key questions, systematically searched and evaluated the literature, created a 1-page algorithm, and advanced 18 recommendations using the Grading of Recommendations Assessment, Development, and Evaluation system.

CONCLUSIONS

This synopsis summarizes the key recommendations of the guideline regarding management of overweight and obesity, including referral to comprehensive lifestyle interventions that combine behavioral, dietary, and physical activity change, and additional tools of pharmacologic and procedural interventions. Additionally, recommendations based on evidence found in the literature for short-term weight loss are included. A clinical practice algorithm that is part of the guideline is also included. Additional materials, such as provider and patient summaries and a provider pocket card, are also available for public use, accessible at the U.S. Veterans Health Administration (VHA) Clinical Practice Guidelines (CPG) website listed above.

Effects of Calorie Restriction on Health Span and Insulin Resistance: Classic Calorie Restriction Diet vs. Ketosis-Inducing Diet

As the incidence of Chronic Non-Communicable Diseases (CNCDs) increases, preventive approaches become more crucial. In this review, calorie restriction (CR) effects on human beings were evaluated, comparing the benefits and risks of different CR diets: classic CR vs. ketosis-inducing diets, including intermittent fasting (IF), classic ketogenic diet (CKD), fasting mimicking diet (FMD), very-low-calorie ketogenic Diet (VLCKD) and Spanish ketogenic Mediterranean diet (SKMD). Special emphasis on insulin resistance (IR) was placed, as it mediates metabolic syndrome (MS), a known risk factor for CNCD, and is predictive of MS diagnosis. CR is the most robust intervention known to increase lifespan and health span, with high evidence and known biochemical mechanisms. CR improves cardiometabolic risk parameters, boosts exercise insulin sensitivity response, and there may be benefits of implementing moderate CR on healthy young and middle-aged individuals. However, there is insufficient evidence to support long-term CR. CKD is effective for weight and MS management, and may have additional benefits such as prevention of muscle loss and appetite control. SKMD has extreme significance benefits for all the metabolic parameters studied. Studies show inconsistent benefits of IF compared to classic CR. More studies are required to study biochemical parameters, reinforce evidence, identify risks, and seek effective and safe nutritional CR approaches.

The Low-Carbohydrate Diet: Short-Term Metabolic Efficacy Versus Longer-Term Limitations

Background: Diets have been a central component of lifestyle modification for decades. The Low-Carbohydrate Diet (LCD), originally conceived as a treatment strategy for intractable epilepsy (due to its association with ketogenesis), became popular in the 1970s and since then has risen to prominence as a weight loss strategy. Objective: To explore the efficacy, limitations and potential safety concerns of the LCD. Data Sources: We performed a narrative review, based on relevant articles written in English from a Pubmed search, using the terms ‘low carbohydrate diet and metabolic health’. Results: Evidence supports the efficacy of the LCD in the short-term (up to 6-months) for reduction in fat mass and remission of Type 2 Diabetes Mellitus (T2D). However, the longer-term efficacy of the LCD is disappointing, with diminishment of weight loss potential and metabolic benefits of the LCD beyond 6-months of its adoption. Furthermore, practical limitations of the LCD include the associated restriction of food choices that restrict the acceptability of the LCD for the individual, particularly over the longer term. There are also safety concerns of the LCD that stem from nutritional imbalances (with a relative excess of dietary fat and protein intake with associated dyslipidaemia and increased risk of insulin resistance and T2D development) and ketotic effects. Finally, the LCD often results in a reduction in dietary fibre intake, with potentially serious adverse consequences for overall health and the gut microbiota. Conclusions: Although widely adopted, the LCD usually has short-lived metabolic benefits, with limited efficacy and practicality over the longer term. Dietary modification needs tailoring to the individual, with careful a priori assessments of food preferences to ensure acceptability and adherence over the longer term, with avoidance of dietary imbalances and optimization of dietary fibre intake (primarily from plant-based fruit and vegetables), and with a posteriori assessments of the highly individual responses to the LCD. Finally, we need to change our view of diets from simply an excipient for weight loss to an essential component of a healthy lifestyle.

Paleolithic Diet-Effect on the Health Status and Performance of Athletes?

The aim of this meta-analysis was to review the impact of a Paleolithic diet (PD) on selected health indicators (body composition, lipid profile, blood pressure, and carbohydrate metabolism) in the short and long term of nutrition intervention in healthy and unhealthy adults. A systematic review of randomized controlled trials of 21 full-text original human studies was conducted. Both the PD and a variety of healthy diets (control diets (CDs)) caused reduction in anthropometric parameters, both in the short and long term. For many indicators, such as weight (body mass (BM)), body mass index (BMI), and waist circumference (WC), impact was stronger and especially found in the short term. All diets caused a decrease in total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG), albeit the impact of PD was stronger. Among long-term studies, only PD cased a decline in TC and LDL-C. Impact on blood pressure was observed mainly in the short term. PD caused a decrease in fasting plasma (fP) glucose, fP insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) and glycated hemoglobin (HbA1c) in the short run, contrary to CD. In the long term, only PD caused a decrease in fP glucose and fP insulin. Lower positive impact of PD on performance was observed in the group without exercise. Positive effects of the PD on health and the lack of experiments among professional athletes require longer-term interventions to determine the effect of the Paleo diet on athletic performance.

Fat, Sugar or Gut Microbiota in Reducing Cardiometabolic Risk: Does Diet Type Really Matter?

The incidence of cardiometabolic diseases, such as obesity, diabetes, and cardiovascular diseases, is constantly rising. Successful lifestyle changes may limit their incidence, which is why researchers focus on the role of nutrition in this context. The outcomes of studies carried out in past decades have influenced dietary guidelines, which primarily recommend reducing saturated fat as a therapeutic approach for cardiovascular disease prevention, while limiting the role of sugar due to its harmful effects. On the other hand, a low-carbohydrate diet (LCD) as a method of treatment remains controversial. A number of studies on the effect of LCDs on patients with type 2 diabetes mellitus proved that it is a safe and effective method of dietary management. As for the risk of cardiovascular diseases, the source of carbohydrates and fats corresponds with the mortality rate and protective effect of plant-derived components. Additionally, some recent studies have focused on the gut microbiota in relation to cardiometabolic diseases and diet as one of the leading factors affecting microbiota composition. Unfortunately, there is still no precise answer to the question of which a single nutrient plays the most important role in reducing cardiometabolic risk, and this review article presents the current state of the knowledge in this field.

Unpalatable food for thought: Let marketing research guide effective public obesity interventions

The prevalence of obesity is growing unabatedly despite the considerable efforts directed at the problem. Although abundant research has contributed to our understanding of the multifactorial causes of obesity, there is less attention to research that is relevant for guiding social marketers, public health professionals and policymakers in delivering public health interventions for countering and/or preventing the problem of obesity. This review offers six points for identifying and developing research relevant for guiding community-wide obesity interventions based on the idea that an applied marketing research perspective offers a better model for identifying effective interventions than more theoretical academic research. Specifically, the research guiding public health and social marketing interventions needs to (1) provide information on ultimate outcomes (weight, health and unintended consequences) more than intermediate outcomes (beliefs, attitudes and behaviour), (2) report on observations collected over the longer term, (3) use natural settings (even at a cost of internal validity), (4) endeavour to overcome observer-effects, (5) report effect sizes (rather than statistical significance) and (6) use moderator analyses to capture variation in how a population responds to interventions.