Intermittent calorie restriction-a more effective approach to weight loss?

Intermittent compared with continuous calorie restriction for treatment of metabolic dysfunction-associated steatotic liver disease: a randomized clinical trial

BACKGROUND

Calorie restriction has been demonstrated to be effective in treating metabolic dysfunction-associated steatotic liver disease (MASLD). However, it has been limited by poor long-term adherence.

OBJECTIVES

This study aimed to compare intermittent calorie restriction (ICR) with traditional continuous calorie restriction (CCR) for the treatment of MASLD.

METHODS

We conducted a 12-wk, parallel-arm, randomized controlled trial that included 60 adults with MASLD and abnormal glucose metabolism. The participants were randomly assigned to either the ICR group (2 successive days of fasting [∼500 kcal/d] and 5 d of recovery per week) or the CCR group. The primary outcome was liver fat content (LFC) measured by 1H-proton magnetic resonance spectroscopy. The secondary and exploratory outcomes included weight, body composition, glucose, insulin, lipids, and liver stiffness.

RESULTS

The mean reduction in LFC was -20.5% [95% confidence interval (CI): -25.0, -15.9%] in the ICR group and -15.5% (95% CI: -20.3, -10.8%) in the CCR group. Changes in LFC were not significantly different between the 2 groups (P = 0.15), and were homogeneous among different liver segments. The analysis of exploratory endpoints provided clues that the ICR was associated with greater reductions in fat mass and glycosylated hemoglobin. There were no significant differences in changes of weight, lean mass, insulin resistance, triglyceride, and liver stiffness between the 2 groups. Participants showed high adherence to both the ICR and CCR schemes.

CONCLUSIONS

The ICR and CCR schemes had similar effects on reducing LFC, suggesting that the ICR 5:2 diet can be an effective alternative for treating MASLD with high adherence.

TRIAL REGISTRATION NUMBER

This trial was registered at clinicaltrials.gov as NCT04283942.

Effect of 12-week intermittent calorie restriction compared to standard of care in patients with nonalcoholic fatty liver disease: a randomized controlled trial

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease. NAFLD can result in various complications. Owing to the lack of effective pharmacological therapies, lifestyle modifications are the cornerstone treatment for NAFLD. However, there has been no recommendation for a specific dietary therapy. Because no significant effects have been observed in previous studies. Intermittent calorie restriction (ICR) consists of alternating phases of extreme energy restriction and regular energy intake. Recent studies have demonstrated a significantly higher reduction in liver fat content in the ICR group than in the standard of care (SOC) or continuous calorie restriction groups in patients with NAFLD. However, critical weaknesses limit the broader application of ICR in clinical practice; those are a lack of appropriate assessment tools, different cutoffs of body mass index (BMI) used to define obesity, and different food portions. Thus, we report a protocol for a prospective, randomized controlled trial. The trial will evaluate the effect of 12-week ICR on improving liver fat content in NAFLD patients (Nonalcoholic Fatty Liver Disease-Intermittent Calorie Restriction [FLICR]).

METHODS

We will include adult (19-75 years) NAFLD patients. NAFLD will be diagnosed by histologic assessment or magnetic resonance imaging-proton density fat fraction (MRI-PDFF) ≥ 8%. A total of 72 patients will be classified according to BMI (obese group: BMI ≥ 25 kg/m2 [n = 36] and non-obese group: BMI < 25 kg/m2 [n = 36]). Participants will be followed up for 24 weeks. Participants will be randomly assigned to one of the two groups: the SOC or ICR group. The primary objective will be the change in liver fat content measured using MRI-PDFF from baseline to 12 weeks.

DISCUSSION

This FLICR study may provide clinical evidence on ICR in the treatment of NAFLD in both obese and non-obese patients. The use of ICR in patients with NAFLD will improve the clinical outcomes of patients facing a shortage of effective medical therapy.

TRIAL REGISTRATION

This trial was registered at the United States National Library of Medicine (NLM) at the National Institutes of Health.

CLINICALTRIALS

gov NCT05309642. Registered on April 4, 2022.

The Effects of Isocaloric Intermittent Fasting vs Daily Caloric Restriction on Weight Loss and Metabolic Risk Factors for Noncommunicable Chronic Diseases: A Systematic Review of Randomized Controlled or Comparative Trials

BACKGROUND

Intermittent fasting (IF) has gained favor as an alternative regimen to daily caloric restriction (DCR). Therefore, there is a need for systematic reviews of randomized controlled/comparison trials examining the effects of isocaloric IF vs DCR on metabolic risk factors for noncommunicable chronic diseases.

OBJECTIVE

To systematically investigate the effects of isocaloric IF vs DCR on metabolic risk factors for noncommunicable chronic diseases in adults with overweight and obesity.

METHODS

Five online databases (PubMed, Scopus, Web of Science, Cochrane Central Register of Controlled Trials, and Google Scholar) were searched for articles published from January 2000 through April 2022. The updated Cochrane Risk of Bias Assessment tool for randomized controlled/comparison trials was used to assess risk of bias in the included studies. This review includes randomized controlled/comparison trials with matched energy intakes (isocaloric) between IF and DCR among adults with overweight and obesity with ≥8-week durations, that assessed risk factors related to obesity and for diabetes, cardiovascular diseases, and cancers.

RESULTS

Thirteen randomized controlled/comparison trials with matched energy intakes (isocaloric) between IF and DCR were identified. The effects of IF on weight loss and metabolic risk markers of diabetes, cardiovascular diseases, and cancers were varied but generally comparable with DCR. IF (4:3 and 5:2 diets) was superior to DCR for improving insulin sensitivity in two studies. Reductions in body fat were significantly greater with IF (5:2 diet and time-restricted eating) than DCR in two studies of isocaloric diets.

CONCLUSIONS

With matched energy intakes, IF interventions produced similar beneficial effects for weight loss and chronic disease risk factors compared with DCR. Very limited evidence suggests that IF may be more effective vs DCR for fat loss and insulin sensitivity, but conclusions cannot be drawn based on the current evidence. Future clinical studies with larger populations and longer durations are needed for further elucidation of any potential effects of IF regimens for prevention of noncommunicable chronic diseases.

Beneficial effects of intermittent fasting: a narrative review

Caloric restriction is a popular approach to treat obesity and its associated chronic illnesses but is difficult to maintain for a long time. Intermittent fasting is an alternative and easily applicable dietary intervention for caloric restriction. Moreover, intermittent fasting has beneficial effects equivalent to those of caloric restriction in terms of body weight control, improvements in glucose homeostasis and lipid profiles, and anti-inflammatory effects. In this review, the beneficial effects of intermittent fasting are discussed.

Effect of time-restricted feeding on body composition and cardio-metabolic risk in middle-aged women in Taiwan

OBJECTIVES

We sought to investigate the effects of time-restricted feeding (TRF) and a traditional weight-loss method on body composition and cardio-metabolic risk factors in middle-aged women.

METHODS

In a single-center, randomized, open-label, parallel-group design, women ages 40 to 65 y with body mass index ≥ 24 kg/m² or waist circumference > 80 cm were recruited. They were guided to a daily low-calorie diet of 1400 kcal and randomly assigned into a TRF group (limit 8 h of eating time and fasting for 16 h) or a non-TRF group (traditional weight-loss method, unrestricted eating time) for 8 wk. Body composition, blood pressure, blood biochemical variables, and insulin resistance status were measured before and after intervention.

RESULTS

Body weight, body mass index, waist circumference, and body fat mass decreased significantly in both groups after 8 wk of intervention (P < 0.05). Body weight decreased more in the TRF group than the non-TRF group (-4.1% ± 2.8% versus -2.4% ± 2.5%; P = 0.012), as did diastolic blood pressure (75.3 ± 11.2 mm Hg versus 70.5 ± 9.4 mm Hg; P = 0.012). There were no statistical differences between the two groups in total cholesterol, triacylglycerols, high- or low-density lipoprotein cholesterol, and fasting insulin level. However, fasting glucose and insulin resistance status increased significantly for the TRF group after the intervention (respectively, 88.3 ± 7.6 mg/dL versus 92.6 ± 9.6 mg/dL, P = 0.003; 1.7 ± 0.7 versus 2.1 ± 1.0, P = 0.048).

CONCLUSION

The weight loss and reduction in diastolic blood pressure using the TRF method were better than with the traditional weight-loss method. However, this method may increase fasting glucose levels and adverse insulin resistance status.

Effect of intermittent and continuous caloric restriction on Sirtuin1 concentration depends on sex and body mass index

BACKGROUND & AIMS

The favorable effect of caloric restriction (CR) on health span is well known and partly mediated by the sirtuin system. Sirtuin1, a regulator of energy homeostasis in response to nutrient availability, is activated by CR. We therefore investigated effects of two different CR regimens on Sirtuin1 concentrations.

METHODS & RESULTS

The study included 112 abdominally obese subjects, randomized to intermittent or continuous CR for 1 year. Blood samples and anthropometric measures were collected at baseline and after 12 months. Sirtuin1 concentrations were measured by ELISA. Sirtuin1 correlated significantly to BMI at baseline (r = .232, p = 0.019). Mean reduction in body-weight was 8.0 and 9.0 kg after intermittent and continuous CR, respectively. After 1 year, no significant between-group differences in Sirtuin1 levels were observed according to regimen (p = 0.98) and sex (p = 0.41). An increase in median Sirtuin1 concentrations (pg/mL) [25, 75 percentiles] from baseline was observed after intermittent CR in the total population (884 [624, 1285] vs.762 [530, 1135]; p = 0.041), most marked in men (820 [623, 1250] vs. 633 [524, 926]; p = 0.016). Improvement in BMI after 1 year correlated to Sirtuin1 changes, but varied according to sex. In women, Spearman's rho = .298, p = 0.034, with stronger correlation in the intermittent CR group (r = .424, p = 0.049). In men, there was an inverse relation to Sirtuin1 changes, only in the intermittent CR group (r = -.396, p = 0.045).

CONCLUSIONS

Effects on Sirtuin1 concentrations after 1 year of CR are sex and BMI-related. Intermittent CR regimen affected Sirtuin1 to a stronger extent than continuous CR, suggesting individualized dietary intervention.

Diets and drugs for weight loss and health in obesity - An update

Numerous combinations of diets and pharmacological agents, including lifestyle changes, have been launched to treat obesity. There are still ambiguities regarding the efficacies of different approaches despite many clinical trials and the use of animal models to study physiological mechanisms in weight management and obesity comorbidities, Here, we present an update on promising diets and pharmacological aids. Literature published after the year 2005 was searched in PubMed, Medline and Google scholar. Among recommended diets are low-fat (LF) and low-carbohydrate (LC) diets, in addition to the Mediterranean diet and the intermittent fasting approach, all of which presumably being optimized by adequate contents of dietary fibers. A basic point for weight loss is to adopt a diet that creates a permanently negative and acceptable energy balance, and prolonged dietary adherence is a crucial factor. As for pharmacological aids, obese patients with type 2 diabetes or insulin resistance seem to benefit from LC diet combined with a GLP-1 agonist, e.g. semaglutide, which may improve glycemic control, stimulate satiety, and suppress appetite. The lipase inhibitor orlistat is still used to maintain a low-fat approach, which may be favorable e.g. in hypercholesterolemia. The bupropion-naltrexone-combination appears promising for interruption of the vicious cycle of addictive over-eating. Successful weight loss seems to improve almost all biomarkers of obesity comorbidities. Until more support for specific strategies is available, clinicians should recommend an adapted lifestyle, and when necessary, a drug combination tailored to individual needs and comorbidities. Different diets may change hormonal secretion, gut-brain signaling, and influence hunger, satiety and energy expenditure. Further research is needed to clarify mechanisms and how such knowledge can be used in weight management.

Adherence and Dietary Composition during Intermittent vs. Continuous Calorie Restriction: Follow-Up Data from a Randomized Controlled Trial in Adults with Overweight or Obesity

Although intermittent calorie restriction (ICR) has become popular as an alternative weight loss strategy to continuous calorie restriction (CCR), there is insufficient evidence on diet quality during ICR and on its feasibility over longer time periods. Thus, we compared dietary composition and adherence between ICR and CCR in a follow-up analysis of a randomized trial. A total of 98 participants with overweight or obesity [BMI (kg/m²) 25-39.9, 35-65 years, 49% females] were randomly assigned to ICR, operationalized as a "5:2 diet" (energy intake: ~100% on five non-restricted (NR) days, ~25% on two restricted (R) days), or CCR (daily energy intake: ~80%). The trial included a 12-week (wk) intervention phase, and follow-up assessments at wk24, wk50 and wk102. Apart from a higher proportion of energy intake from protein with ICR vs. CCR during the intervention (wk2: p < 0.001; wk12: p = 0.002), there were no significant differences with respect to changes in dietary composition over time between the groups, while overall adherence to the interventions appeared to be good. No significant difference between ICR and CCR regarding weight change at wk102 was observed (p = 0.63). However, self-reported adherence was worse for ICR than CCR, with 71.1% vs. 32.5% of the participants reporting not to or only rarely have followed the regimen to which they were assigned between wk50 and wk102. These results indicate that within a weight management setting, ICR and CCR were equivalent in achieving modest weight loss over two years while affecting dietary composition in a comparable manner.