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Effects of Intermittent Energy Restriction Compared with Those of Continuous Energy Restriction on Body Composition and Cardiometabolic Risk Markers - A Systematic Review and Meta-Analysis of Randomized Controlled Trials in Adults.
Schroor, MM, Joris, PJ, Plat, J, Mensink, RP
Advances in nutrition (Bethesda, Md.). 2024;15(1):100130
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Intermittent energy restriction (IER) diets, such as the 5:2 diet, time-restricted eating (TRE), and alternate-day fasting (ADF), are gaining popularity. According to previous research, IER protocols effectively manage obesity and may have many other health benefits, including improving metabolic health. This systematic review and meta-analysis of twenty-eight parallel-design randomised controlled trials looked at the benefits of IER protocols, such as ADF, TRE, and the 5:2 diet, and the effects of continuous energy restriction (CER) on anthropometric and cardiometabolic outcomes. The results of this systematic review and meta-analysis showed that both the IER and CER are equally beneficial. However, IER protocols showed greater but clinically insignificant improvements in fat-free mass and waist circumference in healthy adults. IER and CER protocols were not different in improving the lipid profile, glucose and insulin levels and blood pressure. Different IER diets showed different positive effects on metabolic parameters. Future robust studies are required to assess the effects of these energy-restriction diets on metabolic and anthropometric parameters because of the high variability in the included studies. However, healthcare professionals can use the results of this review to understand the potential clinical utility of various energy-restriction diets.
Abstract
The interest in intermittent energy restriction (IER) diets as a weight-loss approach is increasing. Different IER protocols exist, including time-restricted eating (TRE), alternate-day fasting (ADF), and the 5:2 diet. This meta-analysis compared the effects of these IER diets with continuous energy restriction (CER) on anthropometrics and cardiometabolic risk markers in healthy adults. Twenty-eight trials were identified that studied TRE (k = 7), ADF (k = 10), or the 5:2 diet (k = 11) for 2-52 wk. Energy intakes between intervention groups within a study were comparable (17 trials), lower in IER (5 trials), or not reported (6 trials). Weighted mean differences (WMDs) were calculated using fixed- or random-effects models. Changes in body weight [WMD: -0.42 kg; 95% confidence interval (CI): -0.96 to 0.13; P = 0.132] and fat mass (FM) (WMD: -0.31 kg; 95% CI: -0.98 to 0.36; P = 0.362) were comparable when results of the 3 IER diets were combined and compared with those of CER. All IER diets combined reduced fat-free mass (WMD: -0.20 kg; 95% CI: -0.39 to -0.01; P = 0.044) and waist circumference (WMD: -0.91 cm; 95% CI: -1.76 to -0.06; P = 0.036) more than CER. Effects on body mass index [BMI (kg/m2)], glucose, insulin, homeostatic model assessment for insulin resistance (HOMA-IR), serum lipid and lipoprotein concentrations, and blood pressure did not differ. Further, TRE reduced body weight, FM, and fat-free mass more than CER, whereas ADF improved HOMA-IR more. BMI was reduced less in the 5:2 diet compared with CER. In conclusion, the 3 IER diets combined did not lead to superior improvements in anthropometrics and cardiometabolic risk markers compared with CER diets. Slightly greater reductions were, however, observed in fat-free mass and waist circumference. To what extent differences in energy intakes between groups within studies may have influenced these outcomes should be addressed in future studies.
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Resistance Training Prevents Muscle Loss Induced by Caloric Restriction in Obese Elderly Individuals: A Systematic Review and Meta-Analysis.
Sardeli, AV, Komatsu, TR, Mori, MA, Gáspari, AF, Chacon-Mikahil, MPT
Nutrients. 2018;10(4)
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Caloric restriction (55% carbohydrate, 15% protein, 30% fat) is associated with increased lifespans and the attenuation of the harmful effects of aging. Furthermore, it has been shown that resistance training increases lean body mass, promotes strength, and attenuates muscle loss and function in elderly people. The aim of the study is to determine the level of lean body mass that can be preserved when resistance training is associated with caloric restriction interventions in elderly obese humans. The study is a meta-analysis, based on data from randomised-controlled trials. The participants were older adults or elderly people with a mean age > 57 year. Results indicate that caloric restriction associated with resistance training prevents 93% lean body mass loss induced by caloric restriction. Authors conclude that caloric restriction with resistance training almost stopped caloric restriction induced lean body mass loss completely.
Abstract
It remains unclear as to what extent resistance training (RT) can attenuate muscle loss during caloric restriction (CR) interventions in humans. The objective here is to address if RT could attenuate muscle loss induced by CR in obese elderly individuals, through summarized effects of previous studies. Databases MEDLINE, Embase and Web of Science were used to perform a systematic search between July and August 2017. Were included in the review randomized clinical trials (RCT) comparing the effects of CR with (CRRT) or without RT on lean body mass (LBM), fat body mass (FBM), and total body mass (BM), measured by dual-energy X-ray absorptiometry, on obese elderly individuals. The six RCTs included in the review applied RT three times per week, for 12 to 24 weeks, and most CR interventions followed diets of 55% carbohydrate, 15% protein, and 30% fat. RT reduced 93.5% of CR-induced LBM loss (0.819 kg [0.364 to 1.273]), with similar reduction in FBM and BM, compared with CR. Furthermore, to address muscle quality, the change in strength/LBM ratio tended to be different (p = 0.07) following CRRT (20.9 ± 23.1%) and CR interventions (−7.5 ± 9.9%). Our conclusion is that CRRT is able to prevent almost 100% of CR-induced muscle loss, while resulting in FBM and BM reductions that do not significantly differ from CR.