High-Protein Intake during Weight Loss Therapy Eliminates the Weight-Loss-Induced Improvement in Insulin Action in Obese Postmenopausal Women

Prophylactic effects of nutrition, dietary strategies, exercise, lifestyle and environment on nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease and its prevalence has risen sharply. However, whether nutrition, dietary strategies, exercise, lifestyle and environment have preventive value for NAFLD remains unclear.

METHODS

Through searching 4 databases (PubMed, Web of Science, Embase and the Cochrane Library) from inception to January 2025, we selected studies about nutrition, dietary strategies, exercise, lifestyle and environment in the prevention of NAFLD and conducted a narrative review on this topic.

RESULTS

Reasonable nutrient intake encompassing macronutrients and micronutrients have an independent protective relationship with NAFLD. Besides, proper dietary strategies including mediterranean diet, intermittent fasting diet, ketogenic diet, and dietary approaches to stop hypertension diet have their inhibitory effects on the developmental process of NAFLD. Moreover, right exercises including walking, jogging, bicycling, and swimming are recommended for the prevention of NAFLD because they could effectively reduce weight, which is an important risk factor for NAFLD, and improve liver function. In addition, embracing a healthy lifestyle including reducing sedentary behavior, not smoking, sleeping well and brushing teeth regularly is integral since it not only could reduce the risk of NAFLD but also significantly contribute to overall prevention and control. Finally, the environment, including the social and natural environments, plays a potential role in NAFLD prevention.

CONCLUSION

Nutrition, dietary strategies, exercise, lifestyle and environment play an important role in the prevention of NAFLD. Moreover, this review offers comprehensive prevention recommendations for people at high risk of NAFLD.

Clinical staging to guide management of metabolic disorders and their sequelae: a European Atherosclerosis Society consensus statement

Obesity rates have surged since 1990 worldwide. This rise is paralleled by increases in pathological processes affecting organs such as the heart, liver, and kidneys, here termed systemic metabolic disorders (SMDs). For clinical management of SMD, the European Atherosclerosis Society proposes a pathophysiology-based system comprising three stages: Stage 1, where metabolic abnormalities such as dysfunctional adiposity and dyslipidaemia occur without detectable organ damage; Stage 2, which involves early organ damage manifested as Type 2 diabetes, asymptomatic diastolic dysfunction, metabolic-associated steatohepatitis (MASH), and chronic kidney disease (CKD); and Stage 3, characterized by more advanced organ damage affecting multiple organs. Various forms of high-risk obesity, driven by maintained positive energy balance, are the most common cause of SMD, leading to ectopic lipid accumulation and insulin resistance. This progression affects various organs, promoting comorbidities such as hypertension and atherogenic dyslipidaemia. Genetic factors influence SMD susceptibility, and ethnic disparities in SMD are attributable to genetic and socioeconomic factors. Key SMD features include insulin resistance, inflammation, pre-diabetes, Type 2 diabetes, MASH, hypertension, CKD, atherogenic dyslipidaemia, and heart failure. Management strategies involve lifestyle changes, pharmacotherapy, and metabolic surgery in severe cases, with emerging treatments focusing on genetic approaches. The staging system provides a structured approach to understanding and addressing the multi-faceted nature of SMD, which is crucial for improving health outcomes. Categorization of SMD abnormalities by presence and progression is aimed to improve awareness of a multi-system trait and encourage a tailored and global approach to treatment, ultimately aiming to reduce the burden of obesity-related comorbidities.

Dietary and pharmacological energy restriction and exercise for healthspan extension

Extending healthspan - the years lived in optimal health - holds transformative potential to reduce chronic diseases and healthcare costs. Dietary restriction (DR), particularly when combined with nutrient-rich diets and exercise, is among the most effective, evidence-based strategies for enhancing metabolic health and longevity. By targeting fundamental pathways, it mitigates the onset and progression of obesity, type 2 diabetes (T2D), cardiovascular disease (CVD), neurodegeneration, and cancer. This review synthesizes human data on the impact of DR and exercise on metabolic and age-related diseases, while emphasizing key biological mechanisms such as nutrient sensing, insulin sensitivity, inflammation, mitochondrial function, and gut microbiota. We also examine the emerging role of pharmacologically induced DR, focusing on glucagon-like peptide 1 (GLP-1) receptor agonists (RAs) that partially mimic DR and present opportunities for chronic disease prevention.

Analysis of risk factors affecting obesity in Korean adolescents: based on the 2017-2020 Korea national health and nutrition examination survey

Background

Obesity, which is caused by various congenital factors, lifestyle changes, and modernized eating habits, has recently emerged as a serious health concern in children and adolescents. According to the Korea National Health and Nutrition Examination Survey (KNHANES) conducted from 2007 to 2020, the prevalence of obesity and overweight in youth has shown an increasing trend over time. Notably, obesity has been studied in several studies. However, given its close association with rapidly changing societal environments and lifestyle patterns, continuous updates are necessary. Therefore, investigating the current state of obesity in children and adolescents is crucial. Herein, we investigated factors related to the prevalence of obesity.

Materials and methods

We investigated 1912 adolescents between the ages of 12 and 18 years from 2017 to 2020 using data from the KNHANES. Known and suspected risk factors for lifestyle and eating habits were analyzed using univariate and multivariate logistic regression analyses.

Results

Our study revealed a gradual increase in the proportion of individuals having overweight and obesity. Regarding risk factors for obesity, in the unadjusted model, older age (Odds ratio [OR], 1.11), sedentary time ≥12 h (OR, 1.29), and a higher calorie intake from protein (OR, 1.06) were positively associated with obesity, whereas female sex (OR, 0.52) and sleep duration ≥8 h (OR, 0.56) were negatively associated with obesity. These trends remained consistent in the adjusted model, with older age (OR, 1.10), sedentary time ≥12 h (OR, 1.46), higher protein intake (OR, 1.05), and skipping dinner ≥3 times per week (OR, 2.22) being positively associated with obesity and female sex (OR, 0.60) and sleep duration of 6-8 h (OR, 0.54) and ≥8 h (OR, 0.48) being negatively associated with obesity.

Conclusion

Obesity in Korean adolescents was significantly correlated with shorter sleep duration, more sedentary time, higher protein intake, and frequent meal skipping at dinner. These results highlight the necessity of focused public health initiatives that support healthy living practices, including healthy eating habits, less sedentary activity, and more sleep time.

Sarcopenic obesity and weight loss-induced muscle mass loss

PURPOSE OF REVIEW

Sarcopenic obesity is a clinical condition characterized by the coexistence of excess adiposity and impaired muscle function, associated with heightened cardiometabolic risk and frailty. The emergence of new incretin-based obesity management medications (OMMs), which allow unprecedented weight loss, has raised concerns regarding weight loss-induced fat-free mass (FFM) reduction, including skeletal muscle mass (SMM). This review examines recent findings on the prevalence, diagnosis, and implications of sarcopenic obesity, explores the effects of weight-loss interventions on body composition and their impact on health, and discusses strategies to preserve muscle mass.

RECENT FINDINGS

Weight loss induced by incretin-based OMMs results in a variable but significant reduction in FFM. The extent to which this loss affects SMM and function remains uncertain. Nutritional strategies, particularly adequate protein intake, and structured exercise interventions, especially resistance training, play a key role in mitigating FFM loss. Digital health interventions and telemedicine-based exercise programs offer promising approaches for maintaining muscle health during weight loss.

SUMMARY

The clinical significance of FFM loss during weight reduction remains debated. Future research should refine sarcopenic obesity diagnostic criteria, assess the long-term impact of FFM/SMM reduction during intentional weight loss, and evaluate interventions that optimize body composition while preserving functional health.

Subcutaneous adipose tissue and skeletal muscle mitochondria following weight loss

Obesity is a major global health issue with various metabolic complications. Both bariatric surgery and dieting achieve weight loss and improve whole-body metabolism, but vary in their ability to maintain these improvements over time. Adipose tissue and skeletal muscle metabolism are crucial in weight regulation, and obesity is linked to mitochondrial dysfunction in both tissues. The impact of bariatric surgery versus dieting on adipose tissue and skeletal muscle mitochondrial metabolism remains to be elucidated. Understanding the molecular pathways that modulate tissue metabolism following weight loss holds potential for identifying novel therapeutic targets in obesity management. This narrative review summarizes current knowledge on mitochondrial metabolism following bariatric surgery and diet-induced weight loss in adipose tissue and skeletal muscle, and sheds light on their respective effects.

Sex-Specific Factors Influencing Obesity in Women: Bridging the Gap Between Science and Clinical Practice

Obesity in women is a significant public health issue with serious implications for cardiovascular-kidney-metabolic syndrome and cardiovascular disease. This complex challenge is influenced by physiological, hormonal, socioeconomic, and cultural factors. Women face unique weight management challenges due to hormonal changes during pregnancy, perimenopause, and menopause, which affect fat distribution and increase cardiovascular-kidney-metabolic syndrome risk. Current clinical guidelines often overlook these sex-specific factors, potentially limiting the effectiveness of obesity management strategies in women. This review explores the sex-specific aspects of obesity's pathophysiology, epidemiological trends, and associated comorbidities, focusing on cardiovascular and metabolic complications. This review synthesizes literature on obesity in women, emphasizing sex-specific factors influencing its development and progression. It examines the limitations of body mass index as an obesity measure and explores alternative classification methods. Additionally it investigates the relationship between obesity and comorbidities such as diabetes, hypertension, and dyslipidemia, with a focus on postmenopausal women. Obesity in women is linked to increased risks of cardiovascular-kidney-metabolic syndrome and cardiovascular disease. Hormonal fluctuations throughout life contribute to weight gain and fat distribution patterns specific to women, increasing cardiovascular disease risk. Effective obesity management strategies in women must account for these sex-specific variations. Postmenopausal women are particularly affected by obesity-related complications. Lifestyle interventions, pharmacotherapy, and bariatric surgery have shown efficacy in weight management, though success rates vary. Addressing obesity in women requires a comprehensive approach that considers sex-specific physiological factors, life-stage challenges, and sociocultural barriers. Integrating precision medicine and emerging therapies offers potential for more personalized and effective interventions. Personalized strategies that consider women's biological and life-stage challenges can enhance obesity management and improve cardiovascular outcomes. Future research and clinical practice should focus on developing tailored strategies that address women's unique vulnerabilities to obesity and its associated health risks and on validating sex-specific interventions to improve obesity management in women.

Diverting hepatic lipid fluxes with lifestyles revision and pharmacological interventions as a strategy to tackle steatotic liver disease (SLD) and hepatocellular carcinoma (HCC)

Steatotic liver disease (SLD) and Hepatocellular Carcinoma (HCC) are characterised by a substantial rewiring of lipid fluxes caused by systemic metabolic unbalances and/or disrupted intracellular metabolic pathways. SLD is a direct consequence of the interaction between genetic predisposition and a chronic positive energy balance affecting whole-body energy homeostasis and the function of metabolically-competent organs. In this review, we discuss how the impairment of the cross-talk between peripheral organs and the liver stalls glucose and lipid metabolism, leading to unbalances in hepatic lipid fluxes that promote hepatic fat accumulation. We also describe how prolonged metabolic stress builds up toxic lipid species in the liver, and how lipotoxicity and metabolic disturbances drive disease progression by promoting a chronic activation of wound healing, leading to fibrosis and HCC. Last, we provide a critical overview of current state of the art (pre-clinical and clinical evidence) regarding mechanisms of action and therapeutic efficacy of candidate SLD treatment options, and their potential to interfere with SLD/HCC pathophysiology by diverting lipids away from the liver therefore improving metabolic health.

Low serum glycine strengthens the association between branched-chain amino acids and impaired insulin sensitivity assessed before and after weight loss in a population with pre-diabetes: The PREVIEW_NZ cohort

AIM

Accumulation of circulating branched-chain amino acids (BCAA) is a hallmark feature of impaired insulin sensitivity. As intracellular BCAA catabolism is dependent on glycine availability, we hypothesised that the concurrent measurement of circulating glycine and BCAA may yield a stronger association with markers of insulin sensitivity than either BCAA or glycine alone. This study therefore examined the correlative relationships of BCAA, BCAA and glycine together, plus glycine alone on insulin sensitivity-related markers before and after an 8-week low energy diet (LED) intervention.

METHODS

This is a secondary analysis of the PREVIEW (PREVention of diabetes through lifestyle Intervention and population studies in Europe and around the World) Study New Zealand sub-cohort. Eligible participants with pre-diabetes at baseline who achieved ≥8 % body weight loss following an LED intervention were included, of which 167 paired (Week 0 and Week 8) blood samples were available for amino acid analysis. Glycemic and other data were retrieved from the PREVIEW consortium database. Repeated measures linear mixed models were used to test the association between amino acids and insulin sensitivity-related markers (HOMA2-IR, glucose, insulin, and C-peptide).

RESULTS

Elevated BCAA was associated with impaired insulin sensitivity (p < 0.05), with strength of association (ηp2) almost doubled when glycine was added to the model. However, glycine in isolation was not associated with insulin sensitivity-related markers. The magnitude (β-estimates) of positive association between BCAA and HOMA2-IR, and inverse association between glycine and HOMA2-IR, increased when body weight was higher (Body weight∗BCAA, Body weight∗glycine, p < 0.05, both).

CONCLUSION

Low serum glycine strengthened the association between BCAA and impaired insulin sensitivity. Given that glycine is necessary to facilitate intracellular BCAA catabolism, measurement of glycine is necessary to complement BCAA analysis to comprehensively understand the contribution of amino acid metabolism in insulin sensitivity.

CLINICAL TRIAL REGISTRATION

This study was registered with ClinicalTrials.gov (NCT01777893).

The impact of weight loss on fat-free mass, muscle, bone and hematopoiesis health: Implications for emerging pharmacotherapies aiming at fat reduction and lean mass preservation

Similar to bariatric surgery, incretin receptor agonists have revolutionized the treatment of obesity, achieving up to 15-25 % weight loss in many patients, i.e., at a rate approaching that achieved with bariatric surgery. However, over 25 % of total weight lost from both surgery and pharmacotherapy typically comes from fat-free mass, including skeletal muscle mass, which is often overlooked and can impair metabolic health and increase the risk of subsequent sarcopenic obesity. Loss of muscle and bone as well as anemia can compromise physical function, metabolic rate, and overall health, especially in older adults. The myostatin-activin-follistatin-inhibin system, originally implicated in reproductive function and subsequently muscle regulation, appears to be crucial for muscle and bone maintenance during weight loss. Activins and myostatin promote muscle degradation, while follistatins inhibit their activity in states of negative energy balance, thereby preserving lean mass. Novel compounds in the pipeline, such as Bimagrumab, Trevogrumab, and Garetosmab-which inhibit activin and myostatin signaling-have demonstrated promise in preventing muscle loss while promoting fat loss. Either alone or combined with incretin receptor agonists, these medications may enhance fat loss while preserving or even increasing muscle and bone mass, offering a potential solution for improving body composition and metabolic health during significant weight loss. Since this dual therapeutic approach could help address the challenges of muscle and bone loss during weight loss, well-designed studies are needed to optimize these strategies and assess long-term benefits. For the time being, considerations like advanced age and prefrailty may affect the choice of suitable candidates in clinical practice for current and emerging anti-obesity medications due to the associated risk of sarcopenia.

Efficacy of a High-Protein Diet to Lower Glycemic Levels in Type 2 Diabetes Mellitus: A Systematic Review

Diabetes is a metabolic disease with a high worldwide prevalence and an important factor in mortality and disability in the population. Complications can be reduced or prevented with lifestyle changes in physical activity, dietary habits, and smoking cessation. High-protein diets (HPDs, >30% or >1.0 g/Kg/day) decrease hyperglycemia in part due to their content of branched-chain amino acids (BCAAs), mainly leucine. Leucine (and other BCAAs) improve glucose metabolism by directly signaling in the medio-basal hypothalamus (MBH), increasing liver insulin sensitivity. To determine the effectiveness of an HPD to lower hyperglycemia, we analyzed the results of published clinical studies focusing on the levels of fasting plasma glucose and/or glycosylated hemoglobin (HbA1c) in patients with type 2 diabetes mellitus (T2DM). We carried out a systematic search for clinical studies using HPDs. We searched five databases (Scopus, Web of Science, PubMed, Epistemonikos, and Cochrane), collecting 179 articles and finally selecting 8 articles to analyze their results. In conclusion, HPDs are an effective alternative to reduce hyperglycemia in patients with T2DM, especially so-called Paleolithic diets, due to their higher-quality protein from animal and vegetal sources and their exclusion of grains, dairy products, salt, refined fats, and added sugars.

Dietary protein, amino acids and type 2 diabetes mellitus: a short review

Diabetes is a widespread metabolic disorder and results from insulin resistance and impaired insulin secretion. Modifiable factors like diet, physical activity, and body weight play crucial roles in diabetes prevention, with targeted interventions reducing diabetes risk by about 60%. High-protein consumption, above the recommended intake of 0.8 g/kg body weight per day, have often explored in relation to diabetes risk. However, the relationship between dietary protein and diabetes is multifaceted. Observational studies have linked high total and animal protein intake to an increased risk of type 2 diabetes, particularly in obese women. Elevated levels of branched-chain amino acids (BCAA), which can result from dietary intake, protein breakdown, as well as an impaired catabolism, are strong predictors of cardiometabolic risk and insulin resistance. With several mechanism linking BCAA to insulin resistance. On the other hand, intervention studies suggest that high-protein diets can support weight loss and improve cardiometabolic risk factors. However, the impact on insulin sensitivity and glucose homeostasis is not straightforward. Proteins and amino acids stimulate both insulin and glucagon secretion, influencing glucose levels, but chronic effects remain uncertain. This short narrative review aims to provide an update on the relationship between increased dietary protein intake, amino acids, insulin resistance and type 2 diabetes, and to describe protein recommendations for type 2 diabetes.

Is Weight Loss-Induced Muscle Mass Loss Clinically Relevant?

This Viewpoint explores the effects of weight loss achieved through GLP-1–based antiobesity medications on weight regain, fat-free mass, and skeletal muscle mass in people with obesity.

Mitochondrial redox state, bioenergetics, and calcium transport in caloric restriction: A metabolic nexus

Mitochondria congregate central reactions in energy metabolism, many of which involve electron transfer. As such, they are expected to both respond to changes in nutrient supply and demand and also provide signals that integrate energy metabolism intracellularly. In this review, we discuss how mitochondrial bioenergetics and reactive oxygen species production is impacted by dietary interventions that change nutrient availability and impact on aging, such as calorie restriction. We also discuss how dietary interventions alter mitochondrial Ca2+ transport, regulating both mitochondrial and cytosolic processes modulated by this ion. Overall, a plethora of literature data support the idea that mitochondrial oxidants and calcium transport act as integrating signals coordinating the response to changes in nutritional supply and demand in cells, tissues, and animals.

Plant foods, healthy plant-based diets, and type 2 diabetes: a review of the evidence

Type 2 diabetes (T2D) is a metabolic chronic disease in which insulin resistance and insufficient insulin production lead to elevated blood glucose levels. The prevalence of T2D is growing worldwide, mainly due to obesity and the adoption of Western diets. Replacing animal foods with healthy plant foods is associated with a lower risk of T2D in prospective studies. In randomized controlled trials, the consumption of healthy plant foods in place of animal foods led to cardiometabolic improvements in patients with T2D or who were at high risk of the disease. Dietary patterns that limit or exclude animal foods and focus on healthy plant foods (eg, fruits, vegetables, whole grains, nuts, legumes), known as healthy, plant-based diets, are consistently associated with a lower risk of T2D in cohort studies. The aim of this review is to examine the differential effects of plant foods and animal foods on T2D risk and to describe the existing literature about the role of healthy, plant-based diets, particularly healthy vegan diets, in T2D prevention and management. The evidence from cohort studies and randomized controlled trials will be reported, in addition to the potential biological mechanisms that seem to be involved.

A whole-food, plant-based randomized controlled trial in metastatic breast cancer: weight, cardiometabolic, and hormonal outcomes

PURPOSE

Breast cancer treatment is associated with weight gain, and obesity and its related cardiometabolic and hormonal risk factors have been associated with poorer outcomes. Dietary intervention may address these risk factors, but limited research has been done in the setting of metastatic breast cancer requiring systemic therapy.

METHODS

Women with metastatic breast cancer on stable treatment were randomized 2:1 to an 8-week intervention (n = 21) or control (n = 11). The intervention included weekly assessment visits and an ad libitum whole-food, plant-based (WFPB) diet with provided meals. Cardiometabolic, hormonal, and cancer markers were assessed at baseline, 4 weeks, and 8 weeks.

RESULTS

Within the intervention group, mean weight decreased by 6.6% (p < 0.01) after 8 weeks. Fasting insulin decreased from 16.8 uIU/L to 11.2 uIU/L (p < 0.01), concurrent with significantly reduced insulin resistance. Total cholesterol decreased from 193.6 mg/dL to 159 mg/dL (p < 0.01), and low-density lipoprotein (LDL) cholesterol decreased from 104.6 mg/dL to 82.2 mg/dL (p < 0.01). Total testosterone was unchanged, but free testosterone trended lower within the intervention group (p = 0.08) as sex hormone binding globulin increased from 74.3 nmol/L to 98.2 nmol/L (p < 0.01). There were no significant differences in cancer progression markers at week 8, although mean CA 15-3, CA 27.29, and CEA were lower in the intervention group (p = 0.53, p = 0.23, and p = 0.54, respectively) compared to control, when adjusted for baseline.

CONCLUSION

WFPB dietary changes during treatment for metastatic breast cancer are well tolerated and significantly improve weight, cardiometabolic and hormonal parameters. Longer studies are warranted to assess the durability of changes. Trial registration First registered at Clinicaltrials.gov (NCT03045289) on February 7, 2017.

Association of physical functional activity impairment with severity of sarcopenic obesity: findings from National Health and Nutrition Examination Survey

We aim to clarify the relationship between low skeletal muscle mass and varying levels of adiposity and to identify the types of physical function impairments associated with sarcopenic obesity (SO). This study examined cross-sectional data from the National Health and Nutrition Examination Survey with whole-body dual-energy X-ray absorptiometry (DXA) scans. The data included age, gender, DXA-assessed body composition, and physical functional activity with performing daily tasks by questionnaire. We subdivided the data by body composition into a non-SO group and a SO group (ASMI 0-49.99% and FMI of 50-100%), after which the SO data were subdivided into three classes. A higher class indicated higher adiposity and lower muscle mass. The physical function impairment of the two groups was compared. Our study examined 7161 individuals, of which 4907 did not have SO and 2254 had SO, and their data were further divided into three classes (i.e., class I, 826 individuals; class II, 1300 individuals; and class III, 128 individuals). Significant differences in demographics and DXA parameters were identified between the non-SO and SO groups (P < 0.001); the individuals with SO were older, included more women, and exhibited high adiposity and less lean muscle mass. The individuals with class III SO exhibited greater differences and reported more difficulty in performing daily activities. The individuals with class III SO exhibited the most severe physical function impairment. Our study highlights the considerable difficulties encountered by individuals with SO in performing daily activities. Given this finding, customized rehabilitation strategies should be implemented to improve the quality of life of individuals with SO.

Identification of a leucine-mediated threshold effect governing macrophage mTOR signalling and cardiovascular risk

High protein intake is common in western societies and is often promoted as part of a healthy lifestyle; however, amino-acid-mediated mammalian target of rapamycin (mTOR) signalling in macrophages has been implicated in the pathogenesis of ischaemic cardiovascular disease. In a series of clinical studies on male and female participants ( NCT03946774 and NCT03994367 ) that involved graded amounts of protein ingestion together with detailed plasma amino acid analysis and human monocyte/macrophage experiments, we identify leucine as the key activator of mTOR signalling in macrophages. We describe a threshold effect of high protein intake and circulating leucine on monocytes/macrophages wherein only protein in excess of ∼25 g per meal induces mTOR activation and functional effects. By designing specific diets modified in protein and leucine content representative of the intake in the general population, we confirm this threshold effect in mouse models and find ingestion of protein in excess of ∼22% of dietary energy requirements drives atherosclerosis in male mice. These data demonstrate a mechanistic basis for the adverse impact of excessive dietary protein on cardiovascular risk.

A Whole-Food, Plant-Based Randomized Controlled Trial in Metastatic Breast Cancer: Weight, Cardiometabolic, and Hormonal Outcome

Purpose

Breast cancer treatment is associated with weight gain, and obesity and its related cardiometabolic and hormonal risk factors have been associated with poorer outcomes. Dietary intervention may address these risk factors, but limited research has been done in the setting of metastatic breast cancer requiring systemic therapy.

Methods

Women with metastatic breast cancer on stable treatment were randomized 2:1 to an 8-week intervention (n = 21) or control (n = 11). The intervention included weekly assessment visits and an ad libitum whole food, plant-based (WFPB) diet with provided meals. Cardiometabolic, hormonal, and cancer markers were assessed at baseline, 4 weeks, and 8 weeks.

Results

Within the intervention group, mean weight decreased by 6.6% (p < 0.01) after 8 weeks. Fasting insulin decreased from 16.8 uIU/L to 11.2 uIU/L (p < 0.01), concurrent with significantly reduced insulin resistance. Total cholesterol decreased from 193.6 mg/dL to 159 mg/dL (p < 0.01) and low-density lipoprotein (LDL) cholesterol decreased from 104.6 mg/dL to 82.2 mg/dL (p < 0.01). Total testosterone was unchanged, but free testosterone trended lower within the intervention group (p = 0.08) as sex hormone binding globulin increased from 74.3 nmol/L to 98.2 nmol/L (p < 0.01). There were no significant differences in cancer progression markers at week 8, although mean CA 15 - 3, CA 27.29, and CEA were lower in the intervention group (p = 0.53, p = 0.23, and p = 0.54, respectively) compared to control, when adjusted for baseline.

Conclusion

WFPB dietary changes during treatment for metastatic breast cancer are well tolerated and significantly improve weight and cardiometabolic and hormonal parameters. Longer studies are warranted to assess the durability of changes.

Trial registration

First registered at Clinicaltrials.gov (NCT03045289) on February 7, 2017.

Maternal consumption of l-malic acid enriched diets improves antioxidant capacity and glucose metabolism in offspring by regulating the gut microbiota

Maternal diets during pregnancy and lactation are key determinants that regulate the development of metabolic syndrome (MetS) in offspring. l-malic acid (MA) was previously reported to improve antioxidant capacity and aerobic metabolism. However, the effects of maternal MA consumption on the metabolic features of offspring remain largely unexplored. Herein, through pig models consuming MA-enriched diets during late pregnancy and lactation, we found that maternal MA consumption potentiated the anti-inflammatory and antioxidant capacity of sows, thereby improving their reproductive performance and the growth performance of piglets. Maternal MA consumption also induced a transition of slow-twitch to fast-twitch fibers in the early life of offspring. Along with muscle growth and fiber-type transition, insulin sensitivity and glucose metabolism, including aerobic metabolism and glycolysis, were improved in the skeletal muscle of offspring. An untargeted metabolomic analysis further revealed the contribution of modified amino acid metabolism to the improved aerobic metabolism. Mechanistically, maternal MA consumption remodeled colonic microbiota of their offspring. Briefly, the abundance of Colidextribacter, Romboutsia, and Family_XIII_AD3011_group increased, which were positively associated with the antioxidant capacity and glucose metabolism of skeletal muscles. A decreased abundance of Prevotella, Blautia, Prevotellaceae_NK3B31_group, and Collinsella was also detected, which were involved in less insulin sensitivity. Notably, milk metabolites, such as ascorbic acid (AA) and granisetron (GS), were found as key effectors regulating the gut microbiota composition of piglets. The properties of AA and GS in alleviating insulin resistance, inflammation, and oxidative stress were further verified through mice treated with high-fat diets. Overall, this study revealed that maternal MA consumption could modulate the inflammatory response, antioxidant capacity, and glucose metabolism by regulating the gut microbiota of offspring through the vertical transmission of milk metabolites. These findings suggest the potential of MA in the prevention and treatment of MetS in early life.

Vegetarian and vegan diets: benefits and drawbacks

Plant-based diets have become increasingly popular thanks to their purported health benefits and more recently for their positive environmental impact. Prospective studies suggest that consuming vegetarian diets is associated with a reduced risk of developing cardiovascular disease (CVD), diabetes, hypertension, dementia, and cancer. Data from randomized clinical trials have confirmed a protective effect of vegetarian diets for the prevention of diabetes and reductions in weight, blood pressure, glycosylated haemoglobin and low-density lipoprotein cholesterol, but to date, no data are available for cardiovascular event rates and cognitive impairment, and there are very limited data for cancer. Moreover, not all plant-based foods are equally healthy. Unhealthy vegetarian diets poor in specific nutrients (vitamin B12, iron, zinc, and calcium) and/or rich in highly processed and refined foods increase morbidity and mortality. Further mechanistic studies are desirable to understand whether the advantages of healthy, minimally processed vegetarian diets represent an all-or-nothing phenomenon and whether consuming primarily plant-based diets containing small quantities of animal products (e.g. pesco-vegetarian or Mediterranean diets) has beneficial, detrimental, or neutral effects on cardiometabolic health outcomes. Further, mechanistic studies are warranted to enhance our understanding about healthy plant-based food patterns and the biological mechanisms linking dietary factors, CVD, and other metabolic diseases.

Protein supplementation changes gut microbial diversity and derived metabolites in subjects with type 2 diabetes

High-protein diets are promoted for individuals with type 2 diabetes (T2D). However, effects of dietary protein interventions on (gut-derived) metabolites in T2D remains understudied. We therefore performed a multi-center, randomized-controlled, isocaloric protein intervention with 151 participants following either 12-week high-protein (HP; 30Energy %, N = 78) vs. low-protein (LP; 10 Energy%, N = 73) diet. Primary objectives were dietary effects on glycemic control which were determined via glycemic excursions, continuous glucose monitors and HbA1c. Secondary objectives were impact of diet on gut microbiota composition and -derived metabolites which were determined by shotgun-metagenomics and mass spectrometry. Analyses were performed using delta changes adjusting for center, baseline, and kidney function when appropriate. This study found that a short-term 12-week isocaloric protein modulation does not affect glycemic parameters or weight in metformin-treated T2D. However, the HP diet slightly worsened kidney function, increased alpha-diversity, and production of potentially harmful microbiota-dependent metabolites, which may affect host metabolism upon prolonged exposure.

Transcriptomic Analysis of Human Skeletal Muscle in Response to Aerobic Exercise and Protein Intake

This study aimed to provide a more comprehensive molecular insight into the effects of aerobic exercise (AE), protein intake (PI), and AE combined with PI on human skeletal muscle by comparing their transcriptomic profiles. Fourteen published datasets obtained from the Gene Expression Omnibus (GEO) database were used. The hub genes were identified in response to acute AE (ACTB, IL6), training AE (UBB, COL1A1), PI (EZH2), acute AE combined with PI (DDIT3), and training AE combined with PI (MYC). Both FOS and MYC were upregulated in response to acute AE, and they were, respectively, downregulated by higher PI and a combination of AE and PI. COL1A1 was upregulated by training AE but was downregulated by higher PI. Results from the gene set enrichment analysis (p < 0.05 and FDR < 25%) showed that AE and PI delivered their impacts on human skeletal muscle in analogous pathways, including aerobic respiration, mitochondrial complexes, extracellular matrix (ECM) remodeling, metabolic process, and immune/inflammatory responses, whereas, PI may attenuate the response of immune/inflammation and ECM remodeling which would be promoted by AE, irrespective of its types. Compared to PI alone, acute AE combined with PI would further promote protein turnover and synthesis, but suppress skeletal muscle contraction and movement.

High- and normal-protein diets improve body composition and glucose control in adults with type 2 diabetes: a randomized trial

OBJECTIVE

Weight loss of ≥10% improves glucose control and may remit type 2 diabetes (T2D). High-protein (HP) diets are commonly used for weight loss, but whether protein sources, especially red meat, impact weight loss-induced T2D management is unknown. This trial compared an HP diet including beef and a normal-protein (NP) diet without red meat for weight loss, body composition changes, and glucose control in individuals with T2D.

METHODS

A total of 106 adults (80 female) with T2D consumed an HP (40% protein) diet with ≥4 weekly servings of lean beef or an NP (21% protein) diet excluding red meat during a 52-week weight loss intervention. Body weight, body composition, and cardiometabolic parameters were measured before and after intervention.

RESULTS

Weight loss was not different between the HP (-10.2 ± 1.6 kg) and NP (-12.7 ± 4.8 kg, p = 0.336) groups. Both groups reduced fat mass and increased fat-free mass percent. Hemoglobin A1c, glucose, insulin, insulin resistance, blood pressure, and triglycerides improved, with no differences between groups.

CONCLUSIONS

The lack of observed effects of dietary protein and red meat consumption on weight loss and improved cardiometabolic health suggests that achieved weight loss, rather than diet composition, should be the principal target of dietary interventions for T2D management.

Comparison of Protein- or Amino Acid-Based Supplements in the Rehabilitation of Men with Severe Obesity: A Randomized Controlled Pilot Study

BACKGROUND

Weight loss is associated with a reduction in all body compartments, including muscle mass (MM), and this effect produces a decrease in function and muscle strength. Our objective was to assess the impact of protein or amino acid supplements on MM loss in middle-aged men (age < 65 years) with severe obesity (BMI > 35 kg/m2) during weight loss.

MATERIALS AND METHODS

We conducted a single-site randomized controlled trial (Clinicaltrials.gov NCT05143398) with 40 in-patient male subjects with severe obesity. Participants underwent an intervention program consisting of a low-calorie balanced diet and structured physical activity. They were randomly assigned to 4-week treatment groups: (1) control (CTR, N = 10), (2) protein (P, N = 10), (3) branched-chain amino acid (BCAA, N = 10), and (4) essential amino acid mixture with tricarboxylic acid cycle intermediates (PD-E07, N = 10) supplementation.

RESULTS

Following 4 weeks of intervention, all groups showed similar reductions in body weight compared to baseline. When examining the delta values, a notable increase in muscle mass (MM) was observed in the PD-E07 intervention group [MM (kg): 2.84 ± 3.57; MM (%): 3.63 ± 3.14], in contrast to the CTR group [MM (kg): -2.46 ± 3.04; MM (%): -0.47 ± 2.28], with a statistical significance of p = 0.045 and p = 0.023, respectively. However, the MM values for the P group [MM (kg): -2.75 ± 5.98, p = 0.734; MM (%): -0.44 ± 4.02, p = 0.990] and the BCAA group [MM (kg): -1 ± 3.3, p = 0.734; MM (%): 0.34 ± 2.85, p = 0.956] did not exhibit a statistically significant difference when compared to the CTR group.

CONCLUSIONS

Amino acid-based supplements may effectively mitigate the loss of MM typically observed during weight reduction. Further validation through large-scale studies is necessary.

Relationship between dietary macronutrient composition with weight loss after bariatric surgery: A systematic review

This systematic review evaluated the relationship between macronutrient intake and weight loss after bariatric surgery (BS). The MEDLINE/Pubmed, EMBASE, COCHRANE/CENTRAL, and SCOPUS databases were accessed in August 2021 to search for eligible articles: original publications with adults undergoing BS and indicating the relationship between macronutrients and weight loss. Titles that did not meet these criteria were excluded. The review was written according to the PRISMA guide, and the risk of bias was according to the Joanna Briggs manual. Data were extracted by one reviewer and checked by another. Eight articles with 2.378 subjects were included. The studies indicated a positive relationship between weight loss and protein intake after BS. Prioritization of protein followed by carbohydrates with a lower percentage of lipids favors weight loss and increases weight stability after BS. Among the results found, a 1% increase in protein intake raises the probability of obesity remission by 6%, and high-protein diet increase 50% weight loss success. Limitations are the methods of included studies and review process. It is concluded that high-protein intake >60 g a 90 g/day may favor weight loss and maintenance after BS, but it is relevant to balance the other macronutrients.

Dietary patterns and cardiometabolic health: Clinical evidence and mechanism

For centuries, the search for nutritional interventions to underpin cardiovascular treatment and prevention guidelines has contributed to the rapid development of the field of dietary patterns and cardiometabolic disease (CMD). Numerous studies have demonstrated that healthy dietary patterns with emphasis on food-based recommendations are the gold standard for extending lifespan and reducing the risks of CMD and mortality. Healthy dietary patterns include various permutations of energy restriction, macronutrients, and food intake patterns such as calorie restriction, intermittent fasting, Mediterranean diet, plant-based diets, etc. Early implementation of healthy dietary patterns in patients with CMD is encouraged, but an understanding of the mechanisms by which these patterns trigger cardiometabolic benefits remains incomplete. Hence, this review examined several dietary patterns that may improve cardiometabolic health, including restrictive dietary patterns, regional dietary patterns, and diets based on controlled macronutrients and food groups, summarizing cutting-edge evidence and potential mechanisms for CMD prevention and treatment. Particularly, considering individual differences in responses to dietary composition and nutritional changes in organ tissue diversity, we highlighted the critical role of individual gut microbiota in the crosstalk between diet and CMD and recommend a more precise and dynamic nutritional strategy for CMD by developing dietary patterns based on individual gut microbiota profiles.

Alternative dietary protein sources to support healthy and active skeletal muscle aging

To mitigate the age-related decline in skeletal muscle quantity and quality, and the associated negative health outcomes, it has been proposed that dietary protein recommendations for older adults should be increased alongside an active lifestyle and/or structured exercise training. Concomitantly, there are growing environmental concerns associated with the production of animal-based dietary protein sources. The question therefore arises as to where this dietary protein required for meeting the protein demands of the rapidly aging global population should (or could) be obtained. Various non-animal-derived protein sources possess favorable sustainability credentials, though much less is known (compared with animal-derived proteins) about their ability to influence muscle anabolism. It is also likely that the anabolic potential of various alternative protein sources varies markedly, with the majority of options remaining to be investigated. The purpose of this review was to thoroughly assess the current evidence base for the utility of alternative protein sources (plants, fungi, insects, algae, and lab-grown "meat") to support muscle anabolism in (active) older adults. The solid existing data portfolio requires considerable expansion to encompass the strategic evaluation of the various types of dietary protein sources. Such data will ultimately be necessary to support desirable alterations and refinements in nutritional guidelines to support healthy and active aging, while concomitantly securing a sustainable food future.

Mitochondrial adaptations to calorie restriction and bariatric surgery in human skeletal muscle: a systematic review with meta-analysis

OBJECTIVE

We performed a meta-analysis to determine the changes induced by calorie restriction (CR) and bariatric surgery on human skeletal muscle mitochondria.

METHODS

A systematic search of Medline and Web of Science was conducted. Controlled trials exploring CR (≥14 days) and mitochondrial function and/or content assessment were included. Moreover, studies analyzing weight loss following gastric surgery were included for comparison purposes. Human muscle data from 28 studies assessing CR (520 muscle samples) and from 10 studies assessing bariatric surgery (155 muscle samples) were analyzed in a random effect meta-analysis with three a priori chosen covariates.

MAIN RESULTS

We report a decrease (p < 0.05) (mean (95 % CI)) in maximal mitochondrial state 3 respiration in response to CR (-0.44 (-0.85, -0.03)) but not in response to surgery (-0.33 (-1.18, 0.52)). No changes in mitochondrial content were reported after CR (-0.05 (-0.12, 0.13)) or in response to surgery (0.23 (-0.05, 0.52)). Moreover, data from CR subjects showed a reduction in complex IV (CIV) activity (-0.29 (-0.56, -0.03)) but not in CIV content (-0.21 (-0.63, 0.22)). Similar results were obtained when the length of the protocol, the initial body mass index, and the estimated energy deficit were included in the model as covariates.

CONCLUSION

The observation of reduced maximal mitochondrial state 3, uncoupled respiration, and CIV activity without altering mitochondrial content suggests that, in human skeletal muscle, CR mainly modulates intrinsic mitochondrial function.

Unprocessed red meat in the dietary treatment of obesity: a randomized controlled trial of beef supplementation during weight maintenance after successful weight loss

BACKGROUND

Consumption of unprocessed red meat in randomized trials has no adverse effects on cardiovascular risk factors and body weight, but its physiological effects during weight loss maintenance are not known.

OBJECTIVES

We sought to investigate the effects of healthy diets that include small or large amounts of red meat on the maintenance of lost weight after successful weight loss, and secondarily on body composition (DXA), resting energy expenditure (REE; indirect calorimetry), and cardiometabolic risk factors.

METHODS

In this 5-mo parallel randomized intervention trial, 108 adults with BMI 28-40 kg/m2 (45 males/63 females) underwent an 8-wk rapid weight loss period, and those who lost ≥8% body weight (n = 80) continued to ad libitum weight maintenance diets for 12 wk: a moderate-protein diet with 25 g beef/d (B25, n = 45) or a high-protein diet with 150 g beef/d (B150, n = 35).

RESULTS

In per protocol analysis (n = 69), mean body weight (-1.2 kg; 95% CI: -2.1, -0.3 kg), mean fat mass (-2.7 kg; 95% CI: -3.4, -2.0 kg), and mean body fat content (-2.6%; 95% CI: -3.1, -2.1%) decreased during the maintenance phase, whereas mean lean mass (1.5 kg; 95% CI: 1.0, 2.0 kg) and mean REE (51 kcal/d; 95% CI: 15, 86 kcal/d) increased, with no differences between groups (all P > 0.05). Results were similar in intention-to-treat analysis with multiple imputation for dropouts (20 from B150 compared with 19 from B25, P = 0.929). Changes in cardiometabolic risk factors were not different between groups, the general pattern being a decrease during weight loss and a return to baseline during weight maintenance (and despite the additional mild reduction in weight and fat mass).

CONCLUSIONS

Healthy diets consumed ad libitum that contain a little or a lot of unprocessed beef have similar effects on body weight, energy metabolism, and cardiovascular risk factors during the first 3 mo after clinically significant rapid weight loss.

Gut Microbiota Changes by an SGLT2 Inhibitor, Luseogliflozin, Alters Metabolites Compared with Those in a Low Carbohydrate Diet in db/db Mice

In recent years, sarcopenic obesity has been considered central pathological factors in diabetes. This study aimed to compare the effect of luseogliflozin, a sodium-glucose co-transporter-2 inhibitor (SGLT2i), on sarcopenic obesity in comparison to that of a low-carbohydrate diet (LCD). Twenty-week-old male db/db mice were fed a normal diet (Ctrl), LCD, and normal diet with 0.01% w/w luseogliflozin (SGLT2i) for eight weeks. Skeletal muscle mass and grip strength decreased in the LCD group mice compared to those in the control group, while they increased in the SGLT2i group mice. The amino acid content in the liver, skeletal muscle, and serum were lower in the LCD group than those in the Ctrl group but increased in the SGLT2i group mice. Short-chain fatty acids in rectal feces were lower in the LCD group mice than those in the Ctrl group, whereas they were higher in the SGLT2i group mice. The abundance of Gammaproteobacteria, Enterobacteriaceae, Escherichia, Enterobacterales, and Bacteroides caccae species increased in the LCD group compared to the other two groups, whereas the abundance of Syntrophothermus lipocalidus, Syntrophomonadaceae family, Parabacteroidesdistasonis distasonis, and the genus Anaerotignum increased in the SGLT2i group. Luseogliflozin could prevent sarcopenic obesity by improving amino acid metabolism.

Multiomics assessment of dietary protein titration reveals altered hepatic glucose utilization

Dietary protein restriction (PR) has rapid effects on metabolism including improved glucose and lipid homeostasis, via multiple mechanisms. Here, we investigate responses of fecal microbiome, hepatic transcriptome, and hepatic metabolome to six diets with protein from 18% to 0% of energy in mice. PR alters fecal microbial composition, but metabolic effects are not transferable via fecal transplantation. Hepatic transcriptome and metabolome are significantly altered in diets with lower than 10% energy from protein. Changes upon PR correlate with calorie restriction but with a larger magnitude and specific changes in amino acid (AA) metabolism. PR increases steady-state aspartate, serine, and glutamate and decreases glucose and gluconeogenic intermediates. ¹³C6 glucose and glycerol tracing reveal increased fractional enrichment in aspartate, serine, and glutamate. Changes remain intact in hepatic ATF4 knockout mice. Together, this demonstrates an ATF4-independent shift in gluconeogenic substrate utilization toward specific AAs, with compensation from glycerol to promote a protein-sparing response.

Partially Hydrolyzed Guar Gum Suppresses the Development of Sarcopenic Obesity

Partially hydrolyzed guar gum (PHGG) is a soluble dietary fiber derived through controlled enzymatic hydrolysis of guar gum, a highly viscous galactomannan derived from the seeds of Cyamopsis tetragonoloba. Here, we examined the therapeutic potential of dietary supplementation with PHGG against sarcopenic obesity using Db/Db mice. Db/Db mice fed a normal diet alone or a fiber-free diet, or supplemented with a diet containing PHGG (5%), were examined. PHGG increased grip strength and the weight of skeletal muscles. PHGG increased the short-chain fatty acids (SCFAs) concentration in feces and sera. Concerning innate immunity, PHGG decreased the ratio of inflammatory cells, while increasing the ratio of anti-inflammatory cells in the small intestine. The present study demonstrated the preventive effect of PHGG on sarcopenic obesity. Changes in nutrient absorption might be involved through the promotion of an anti-inflammatory shift of innate immunity in the intestine accompanied by an increase in SCFA production by PHGG.

Impact of physical exercise and caloric restriction in patients with type 2 diabetes: Skeletal muscle insulin resistance and mitochondrial dysfunction as ideal therapeutic targets

Skeletal muscle insulin resistance and mitochondrial dysfunction are some of the major pathological defects implicated in the development of type 2 diabetes (T2D). Therefore, it has become necessary to understand how common interventions such as physical exercise and caloric restriction affect metabolic function, including physiological processes that implicate skeletal muscle dysfunction within a state of T2D. This review critically discusses evidence on the impact of physical exercise and caloric restriction on markers of insulin resistance and mitochondrial dysfunction within the skeletal muscle of patients with T2D or related metabolic complications. Importantly, relevant information from clinical studies was acquired through a systematic approach targeting major electronic databases and search engines such as PubMed, Google Scholar, and Cochrane library. The reported evidence suggests that interventions like physical exercise and caloric restriction, within a duration of approximately 2 to 4 months, can improve insulin sensitivity, in part by targeting the phosphoinositide 3-kinases/protein kinase B pathway in patients with T2D. Furthermore, both physical exercise and caloric restriction can effectively modulate markers related to improved mitochondrial function and dynamics. This was consistent with an improved modulation of mitochondrial oxidative capacity and reduced production of reactive oxygen species in patients with T2D or related metabolic complications. However, such conclusions are based on limited evidence, additional clinical trials are required to better understand these interventions on pathological mechanisms of T2D and related abnormalities.

Does a Higher Protein Diet Promote Satiety and Weight Loss Independent of Carbohydrate Content? An 8-Week Low-Energy Diet (LED) Intervention

Both higher protein (HP) and lower carbohydrate (LC) diets may promote satiety and enhance body weight (BW) loss. This study investigated whether HP can promote these outcomes independent of carbohydrate (CHO) content. 121 women with obesity (BW: 95.1 ± 13.0 kg, BMI: 35.4 ± 3.9 kg/m2) were randomised to either HP (1.2 g/kg BW) or normal protein (NP, 0.8 g/kg BW) diets, in combination with either LC (28 en%) or normal CHO (NC, 40 en%) diets. A low-energy diet partial diet replacement (LEDpdr) regime was used for 8 weeks, where participants consumed fixed-energy meal replacements plus one ad libitum meal daily. Four-day dietary records showed that daily energy intake (EI) was similar between groups (p = 0.744), but the difference in protein and CHO between groups was lower than expected. Following multiple imputation (completion rate 77%), decrease in mean BW, fat mass (FM) and fat-free mass (FFM) at Week 8 in all was 7.5 ± 0.7 kg (p < 0.001), 5.7 ± 0.5 kg (p < 0.001), and 1.4 ± 0.7 kg (p = 0.054) respectively, but with no significant difference between diet groups. LC (CHO×Week, p < 0.05), but not HP, significantly promoted postprandial satiety during a preload challenge. Improvements in blood biomarkers were unrelated to LEDpdr macronutrient composition. In conclusion, HP did not promote satiety and BW loss compared to NP LEDpdr, irrespective of CHO content.

Molecular mechanisms of dietary restriction promoting health and longevity

Dietary restriction with adequate nutrition is the gold standard for delaying ageing and extending healthspan and lifespan in diverse species, including rodents and non-human primates. In this Review, we discuss the effects of dietary restriction in these mammalian model organisms and discuss accumulating data that suggest that dietary restriction results in many of the same physiological, metabolic and molecular changes responsible for the prevention of multiple ageing-associated diseases in humans. We further discuss how different forms of fasting, protein restriction and specific reductions in the levels of essential amino acids such as methionine and the branched-chain amino acids selectively impact the activity of AKT, FOXO, mTOR, nicotinamide adenine dinucleotide (NAD+), AMP-activated protein kinase (AMPK) and fibroblast growth factor 21 (FGF21), which are key components of some of the most important nutrient-sensing geroprotective signalling pathways that promote healthy longevity.

Subcutaneous Adipose Tissue Metabolic Function and Insulin Sensitivity in People With Obesity

We used stable isotope-labeled glucose and palmitate tracer infusions, a hyperinsulinemic-euglycemic clamp, positron emission tomography of muscles and adipose tissue after [18F]fluorodeoxyglucose and [15O]water injections, and subcutaneous adipose tissue (SAT) biopsy to test the hypotheses that 1) increased glucose uptake in SAT is responsible for high insulin-stimulated whole-body glucose uptake in people with obesity who are insulin sensitive and 2) putative SAT factors thought to cause insulin resistance are present in people with obesity who are insulin resistant but not in those who are insulin sensitive. We found that high insulin-stimulated whole-body glucose uptake in insulin-sensitive participants with obesity was not due to channeling of glucose into SAT but, rather, was due to high insulin-stimulated muscle glucose uptake. Furthermore, insulin-stimulated muscle glucose uptake was not different between insulin-sensitive obese and lean participants even though adipocytes were larger, SAT perfusion and oxygenation were lower, and markers of SAT inflammation, fatty acid appearance in plasma in relation to fat-free mass, and plasma fatty acid concentration were higher in the insulin-sensitive obese than in lean participants. In addition, we observed only marginal or no differences in adipocyte size, SAT perfusion and oxygenation, and markers of SAT inflammation between insulin-resistant and insulin-sensitive obese participants. Plasma fatty acid concentration was also not different between insulin-sensitive and insulin-resistant obese participants, even though SAT was resistant to the inhibitory effect of insulin on lipolysis in the insulin-resistant obese group. These data suggest that several putative SAT factors commonly implicated in causing insulin resistance are normal consequences of SAT expansion unrelated to insulin resistance.

Protein, Calcium, Vitamin D Intake and 25(OH)D Status in Normal Weight, Overweight, and Obese Older Adults: A Systematic Review and Meta-Analysis

The aging process is often accompanied by increase in body weight. Older adults with overweight or obesity might have an overconsumption in energy that is accompanied by inadequate intake of protein, vitamin D, and calcium. It is unclear if intake of protein and vitamin D and calcium is sufficient in older adults with overweight/obesity, and whether it differs from older adults with normal weight, since a recent overview of the literature review is lacking. Therefore, we systematically analyzed the current evidence on differences in nutrient intake/status of protein, vitamin D and calcium between older adults with different body mass index (BMI) categories. Randomized controlled trials and prospective cohort studies were identified from PubMed and EMBASE. Studies reporting nutrient intake/status in older adults aged ≥50 years with overweight/obesity and studies comparing between overweight/obesity and normal weight were included. Nutrient intake/status baseline values were reviewed and when possible calculated for one BMI category (single-group meta-analysis), or compared between BMI categories (meta-analysis). Nutrient intake/status was compared with international recommendations. Mean protein (N = 8) and calcium intake (N = 5) was 0.98 gram/kilogram body weight/day (g/kg/d) [95% Confidence Interval (CI) 0.89-1.08] and 965 mg [95% CI: 704-1225] in overweight/obese. Vitamin D intake was insufficient in all BMI categories (N = 5). The pooled mean for vitamin D intake was 6 ug [95% CI 4-9]. For 25(OH)D, the pooled mean was 54 nmol/L [95% CI 45-62], 52 nmol/L [95% CI 46-58], and 48 nmol/l [95% CI 33-62] in normal (N = 7), combined overweight and obese (N = 12), and obese older adults (N = 4), respectively. In conclusion, older adults with overweight and obesity have a borderline sufficient protein and sufficient calcium intake, but insufficient vitamin D intake. The 25(OH)D concentration is deficient for the obese older adults.

Total protein, not amino acid composition, differs in plant-based versus omnivorous dietary patterns and determines metabolic health effects in mice

Plant-based dietary patterns are associated with improved cardiometabolic health, but causal dietary components are unclear. Protein has been proposed to play a role, but the importance of protein quantity versus quality remains unknown. We investigated the contributions of total protein amount, amino acid (AA) composition, and plant versus animal source. Analysis of total protein and AA composition of food items and dietary patterns revealed differences between individual food items, but few differences between AA profiles of vegan versus omnivorous dietary patterns. Effects of protein quantity, but not quality, on cardiometabolic health markers were observed in mice using semi-purified diets with crystalline AAs in plant versus animal-based ratios and naturally sourced diets with whole-food ingredients. Our data show relatively little difference in protein quality between plant-based and omnivorous dietary patterns and that reduced total protein intake in plant-based dietary patterns may be a contributor to the benefits of plant-based diets.

Effects of Quality and Quantity of Protein Intake for Type 2 Diabetes Mellitus Prevention and Metabolic Control

PURPOSE OF REVIEW

The aim of this review is to evaluate the ideal protein quality and quantity and the dietary composition for the prevention and metabolic control of type 2 diabetes mellitus (T2DM).

INTRODUCTION

Although some reviews demonstrate the advantages of a diet with a higher protein intake, other reviews have observed that a diet high in carbohydrates, with low-glycaemic index carbohydrates and good fibre intake, is equally effective in improving insulin sensitivity.

METHODS

Over 2831 articles were screened, and 24 from the last 5 years were analysed and summarised for this review, using the protein, diabetes and insulin glucose metabolic keywords in Pubmed in June 2019.

RESULTS

Eleven studies demonstrate that a higher consumption of proteins has a positive effect on insulin sensitivity. A higher intake of animal protein seems to be related to an increased risk of T2DM. Four studies show that consumption of meat has a deleterious effect. Higher intake of plant protein and dairy products is associated with a modestly reduced risk.

DISCUSSION

Based on the results obtained, for the prevention of T2DM and all disorders related to metabolic syndrome, no ideal dietary composition has yet been found. The advantage of plant protein sources may be related to the foods' low-glycaemic index due to the high fibre content. However, the right protein quality (animal and plant) and the quantity for T2DM prevention and metabolic control are unclear and need to be investigated with further long-term studies.

Weight Loss Strategies and the Risk of Skeletal Muscle Mass Loss

With energy intake restriction and exercise remaining the key diet and lifestyle approaches to weight loss, this is not without potential negative implications for body composition, metabolic health, and quality and quantity of life. Ideally, weight loss should be derived almost exclusively from the fat mass compartment as this is the main driver of metabolic disease, however, several studies have shown that there is an accompanying loss of tissue from the fat-free compartment, especially skeletal muscle. Population groups including post-menopausal women, the elderly, those with metabolic disease and athletes may be particularly at risk of skeletal muscle loss when following a weight management programme. Research studies that have addressed this issue across a range of population groups are reviewed with a focus upon the contribution of resistance and endurance forms of exercise and a higher intake dietary protein above the current guideline of 0.8 g/kg body weight/day. While findings can be contradictory, overall, the consensus appears that fat-free and skeletal muscle masses can be preserved, albeit to varying degrees by including both forms of exercise (but especially resistance forms) in the weight management intervention. Equally, higher intakes of protein can protect loss of these body compartments, acting either separately or synergistically with exercise. Elderly individuals in particular may benefit most from this approach. Thus, the evidence supports the recommendations for intakes of protein above the current guidelines of 0.8 g/kg body weight/d for the healthy elderly population to also be incorporated into the dietary prescription for weight management in this age group.

Anabolic Resistance of Muscle Protein Turnover Comes in Various Shapes and Sizes

Anabolic resistance is defined by a blunted stimulation of muscle protein synthesis rates (MPS) to common anabolic stimuli in skeletal muscle tissue such as dietary protein and exercise. Generally, MPS is the target of most exercise and feeding interventions as muscle protein breakdown rates seem to be less responsive to these stimuli. Ultimately, the blunted responsiveness of MPS to dietary protein and exercise underpins the loss of the amount and quality of skeletal muscle mass leading to decrements in physical performance in these populations. The increase of both habitual physical activity (including structured exercise that targets general fitness characteristics) and protein dense food ingestion are frontline strategies utilized to support muscle mass, performance, and health. In this paper, we discuss anabolic resistance as a common denominator underpinning muscle mass loss with aging, obesity, and other disease states. Namely, we discuss the fact that anabolic resistance exists as a dimmer switch, capable of varying from higher to lower levels of resistance, to the main anabolic stimuli of feeding and exercise depending on the population. Moreover, we review the evidence on whether increased physical activity and targeted exercise can be leveraged to restore the sensitivity of skeletal muscle tissue to dietary amino acids regardless of the population.

Heterogeneity in insulin-stimulated glucose uptake among different muscle groups in healthy lean people and people with obesity

AIMS/HYPOTHESIS

It has been proposed that muscle fibre type composition and perfusion are key determinants of insulin-stimulated muscle glucose uptake, and alterations in muscle fibre type composition and perfusion contribute to muscle, and consequently whole-body, insulin resistance in people with obesity. The goal of the study was to evaluate the relationships among muscle fibre type composition, perfusion and insulin-stimulated glucose uptake rates in healthy, lean people and people with obesity.

METHODS

We measured insulin-stimulated whole-body glucose disposal and glucose uptake and perfusion rates in five major muscle groups (erector spinae, obliques, rectus abdominis, hamstrings, quadriceps) in 15 healthy lean people and 37 people with obesity by using the hyperinsulinaemic-euglycaemic clamp procedure in conjunction with [²H]glucose tracer infusion (to assess whole-body glucose disposal) and positron emission tomography after injections of [¹⁵O]H₂O (to assess muscle perfusion) and [¹⁸F]fluorodeoxyglucose (to assess muscle glucose uptake). A biopsy from the vastus lateralis was obtained to assess fibre type composition.

RESULTS

We found: (1) a twofold difference in glucose uptake rates among muscles in both the lean and obese groups (rectus abdominis: 67 [51, 78] and 32 [21, 55] μmol kg^-1 min^-1 in the lean and obese groups, respectively; erector spinae: 134 [103, 160] and 66 [24, 129] μmol kg^-1 min^-1, respectively; median [IQR]) that was unrelated to perfusion or fibre type composition (assessed in the vastus only); (2) the impairment in insulin action in the obese compared with the lean group was not different among muscle groups; and (3) insulin-stimulated whole-body glucose disposal expressed per kg fat-free mass was linearly related with muscle glucose uptake rate (r² = 0.65, p < 0.05).

CONCLUSIONS/INTERPRETATION

Obesity-associated insulin resistance is generalised across all major muscles, and is not caused by alterations in muscle fibre type composition or perfusion. In addition, insulin-stimulated whole-body glucose disposal relative to fat-free mass provides a reliable index of muscle glucose uptake rate.

Deficits in the Skeletal Muscle Transcriptome and Mitochondrial Coupling in Progressive Diabetes-Induced CKD Relate to Functional Decline

Two-thirds of people with type 2 diabetes mellitus (T2DM) have or will develop chronic kidney disease (CKD), which is characterized by rapid renal decline that, together with superimposed T2DM-related metabolic sequelae, synergistically promotes early frailty and mobility deficits that increase the risk of mortality. Distinguishing the mechanisms linking renal decline to mobility deficits in CKD progression and/or increasing severity in T2DM is instrumental both in identifying those at high risk for functional decline and in formulating effective treatment strategies to prevent renal failure. While evidence suggests that skeletal muscle energetics may relate to the development of these comorbidities in advanced CKD, this has never been assessed across the spectrum of CKD progression, especially in T2DM-induced CKD. Here, using next-generation sequencing, we first report significant downregulation in transcriptional networks governing oxidative phosphorylation, coupled electron transport, electron transport chain (ETC) complex assembly, and mitochondrial organization in both middle- and late-stage CKD in T2DM. Furthermore, muscle mitochondrial coupling is impaired as early as stage 3 CKD, with additional deficits in ETC respiration, enzymatic activity, and increased redox leak. Moreover, mitochondrial ETC function and coupling strongly relate to muscle performance and physical function. Our results indicate that T2DM-induced CKD progression impairs physical function, with implications for altered metabolic transcriptional networks and mitochondrial functional deficits as primary mechanistic factors early in CKD progression in T2DM.

Branched-Chain Amino Acid Supplementation Does Not Preserve Lean Mass or Affect Metabolic Profile in Adults with Overweight or Obesity in a Randomized Controlled Weight Loss Intervention

BACKGROUND

Branched-chain amino acid (BCAA) supplementation has been shown to increase muscle mass or prevent muscle loss during weight loss.

OBJECTIVE

We aimed to investigate the effects of a BCAA-supplemented hypocaloric diet on lean mass preservation and insulin sensitivity.

METHODS

A total of 132 Chinese adults (63 men and 69 women aged 21-45 y, BMI 25-36 kg/m2) were block randomly assigned by gender and BMI into 3 hypocaloric diet (deficit of 500 kcal/d) groups: standard-protein (14%) with placebo (control, CT) or BCAA supplements at 0.1 g · kg-1 body weight · d-1 (BCAA) or high-protein (27%) with placebo (HP). The subjects underwent 16 wk of dietary intervention with provision of meals and supplements, followed by 8 wk of weight maintenance with provision of supplements only. One-way ANOVA analysis was conducted to analyze the primary (lean mass and insulin sensitivity) and secondary outcomes (anthropometric and metabolic parameters) among the 3 groups. Paired t-test was used to analyze the change in each group.

RESULTS

The 3 groups demonstrated similar significant reductions in body weight (7.97%), fat mass (13.8%), and waist circumference (7.27%) after 16 wk of energy deficit. Lean mass loss in BCAA (4.39%) tended to be lower than in CT (5.39%) and higher compared with HP (3.67%) (P = 0.06). Calf muscle volume increased 3.4% in BCAA and intramyocellular lipids (IMCLs) decreased in BCAA (17%) and HP (18%) (P < 0.05) over 16 wk. During the 8 wk weight maintenance period, lean mass gain in BCAA (1.03%) tended to be lower compared with CT (1.58%) and higher than in HP (-0.002%) (P = 0.04). Lean mass gain differed significantly between CT and HP (P = 0.03). Insulin sensitivity and metabolic profiles did not differ among the groups throughout the study period.

CONCLUSIONS

BCAA supplementation does not preserve lean mass or affect insulin sensitivity in overweight and obese adults during weight loss. A higher protein diet may be more advantageous for lean mass preservation.

One-month of a low-energy diet, with no additional effect of high-protein, reduces Obstructive Sleep Apnea severity and improve metabolic parameters in obese males

PURPOSE

Obstructive Sleep Apnea (OSA) is closely associated with obesity. Weight loss ameliorates OSA and its associated metabolic disorders. A high protein intake may improve weight loss through increased energy expenditure, and fat-free mass maintenance during weight loss.

OBJECTIVES

To evaluate the effects of a low-energy, high-protein diet on OSA severity and metabolic parameters in obese men.

METHODS

Forty-five OSA obese (BMI ≥ 30 kg/m²) males were included in this randomized study and submitted to nocturnal polysomnography, body composition measured by plethysmography, biochemical analyses of blood glucose, insulin and lipids, and food intake evaluations before and after one month of a low-energy diet. Diets were designed to create a 30% deficit in total energy expenditure with 1.6 g of protein/kg/day (High Protein group - HP) or 0.8 g of protein/kg/day (Low Protein group - LP).

RESULTS

Only a time effect of the intervention was observed in body mass (-3.7 ± 2.0% for the LP group and -4.0 ± 1.5% for the HP group; p < 0.001), Body Mass Index (p < 0.001), fat mass in kg (p < 0.01) and fat-free mass in kg (p < 0.01). Significant improvements in Apnea Hypopnea Index were observed in both groups (54.0 ± 25.0 to 33.7 ± 31.7 in LP group; 39.7 ± 24.3 to 21.4 ± 25.9 in HP group; p = 0.06). Improvements of 38% and 46% in the Apnea-Hypopnea Index were observed in the LP and HP groups, respectively. Both interventions provided equivalent metabolic benefits as reductions in glucose (p < 0.001), insulin (p < 0.001), HOMA-IR (p = 0.005), triglycerides (p = 0.002), and in total cholesterol (p = 0.004).

CONCLUSION

One month of a low-energy diet resulted in significant improvements in OSA severity in obese men. Increased protein intake during a short period of low-energy diet had no further beneficial effects on OSA severity or biochemical parameters than a standard protein diet. Registered under ClinicalTrials.gov Identifier no. NCT01985035.

Impacts of Selected Dietary Nutrient Intakes on Skeletal Muscle Insulin Sensitivity and Applications to Early Prevention of Type 2 Diabetes

As the largest tissue in the body, skeletal muscle not only plays key roles in movement and glucose uptake and utilization but also mediates insulin sensitivity in the body by myokines. Insulin resistance in the skeletal muscle is a major feature of type 2 diabetes (T2D). A weakened response to insulin could lead to muscle mass loss and dysfunction. Increasing evidence in skeletal muscle cells, rodents, nonhuman primates, and humans has shown that restriction of caloric or protein intake positively mediates insulin sensitivity. Restriction of essential or nonessential amino acids was reported to facilitate glucose utilization and regulate protein turnover in skeletal muscle under certain conditions. Furthermore, some minerals, such as zinc, chromium, vitamins, and some natural phytochemicals such as curcumin, resveratrol, berberine, astragalus polysaccharide, emodin, and genistein, have been shown recently to protect skeletal muscle cells, mice, or humans with or without diabetes from insulin resistance. In this review, we discuss the roles of nutritional interventions in the regulation of skeletal muscle insulin sensitivity. A comprehensive understanding of the nutritional regulation of insulin signaling would contribute to the development of tools and treatment programs for improving skeletal muscle health and for preventing T2D.

The midlife transition and the risk of cardiovascular disease and cancer Part II: strategies to maximize quality of life and limit dysfunction and disease

Chronic dysfunction, disabilities, and complex diseases such as cardiovascular disease, diabetes mellitus type 2, osteoporosis and certain cancers, among other burdens, emerge and accelerate in midlife women. Previously in part l, we described the clinical and laboratory research findings that more readily explain and clarify the underlying pathogenetic mechanisms driving these clinical burdens, including new findings on how in particular visceral obesity and the emergence and acceleration of various components of metabolic syndrome-glucotoxicity and lipotoxicity-and a chronic systemic inflammatory state abetted by the loss of ovarian production of estradiol and the inevitable inroads of aging generate this spectrum of clinical problems. These research insights translate into opportunities for effective care strategies leading to prevention, amelioration, possible correction, and enhanced quality of life. To achieve these goals, updated detailed diagnostic, management, and therapeutic guidelines implemented by a reprogrammed and repurposed "menopause" office visit are described. A triage mechanism-when to refer to other specialists for further care-is emphasized. The previously polarized views of menopausal hormone therapy have narrowed significantly, leading to the construction of a more confident, unified, and wider clinical application. Accordingly, a menopausal hormone therapy program providing maximum benefit and minimum risk, accompanied by an algorithm for enhanced shared decision making, is included.

Effect of the intake of dietary protein on insulin resistance in subjects with obesity: a randomized controlled clinical trial

PURPOSE

We compared the effect of diets with different amounts and sources of dietary protein on insulin sensitivity (IS) in subjects with obesity and insulin resistance (IR).

METHODS

Eighty subjects with obesity (BMI ≥ 30 kg/m²) and IR (Matsuda index < 4.3 and HOMA-IR ≥ 2.5) over 18 years old were randomized to four groups for a one-month period: a normal protein diet (< 20%) with a predominance of animal protein (Animal NP) or vegetable protein (Vegetable NP) and a high-protein diet (25-30%) with a predominance of animal protein (Animal HP) or vegetable protein (Vegetable HP). Baseline and final measurements of body weight, body composition, biochemical parameters, blood pressure (BP), resting energy expenditure and plasma amino acid profiles were performed.

RESULTS

Body weight, BMI and waist circumference decreased in all groups. Interestingly, the IS improved more in the Animal HP (Matsuda index; 1.39 vs 2.58, P = 0.003) and in the Vegetable HP groups (Matsuda index; 1.44 vs 3.14, P < 0.0001) after one month. The fat mass, triglyceride levels, C-reactive protein levels and the leptin/adiponectin index decreased; while, the skeletal muscle mass increased in the Animal and Vegetable HP groups. The BP decreased in all groups except the Animal NP group.

CONCLUSION

Our study demonstrates that a high-protein hypocaloric diets improves IS by 60-90% after one month in subjects with obesity and IR, regardless of weight loss and the source of protein, either animal or vegetable.

TRIAL REGISTRATION

The trial is registered at clinicaltrials.gov (NCT03627104), August 13, 2018.

Dietary protein intake and obesity-associated cardiometabolic function

PURPOSE OF REVIEW

High-protein intake is commonly recommended to help people manage body weight. However, high-protein intake could have adverse health consequences. Here we review the latest findings concerning the effect of high-protein intake on cardiometabolic health.

RECENT FINDINGS

Calorie-reduced, high-protein, low-carbohydrate diets lower plasma glucose in people with type 2 diabetes (T2D). However, when carbohydrate intake is not markedly reduced, high-protein intake often does not alter plasma glucose and increases insulin and glucagon concentrations, which are risk factors for T2D and ischemic heart disease. High-protein intake does not alter plasma triglyceride and cholesterol concentrations but promotes atherogenesis in animal models. The effect of high-protein intake on liver fat remains unclear. In population studies, high-protein intake is associated with increased risk for T2D, nonalcoholic fatty liver disease, and possibly cardiovascular diseases.

SUMMARY

The relationship between protein intake and cardiometabolic health is complex and influenced by concomitant changes in body weight and overall diet composition. Although a high-protein, low-carbohydrate, reduced-energy diet can have beneficial effects on body weight and plasma glucose, habitual high-protein intake, without marked carbohydrate and energy restriction, is associated with increased cardiometabolic disease risk, presumably mediated by the changes in the hormonal milieu after high-protein intake.