The Effects of Intermittent Energy Restriction on Indices of Cardiometabolic Health

Abstract

Intermittent energy restriction (IER) has become the subject of considerable scientific interest as a potential dietary approach for weight-loss and improving cardiometabolic health. This approach involves intermittent periods of total or partial energy restriction (ER) alternated with non-restricted intake, and has been studied in rodent and human populations.This review aims to provide an overview of the IER literature to date, with a specific focus on its effects on cardiometabolic health indices in rodents and humans.Current evidence from studies in rodents and humans suggests that IER is capable of promoting weight-loss and/or favourably influencing an array of cardiometabolic health indices, with equal or greater efficacy than conventional continuous ER approaches. Putative mechanisms include the effects of IER on adipose tissue physiology, stress resistance and fat distribution within visceral and intra-hepatic sites. However, a large proportion of this mechanistic evidence is limited to indirect observations and/or has come from rodent studies requiring translation into humans. Furthermore, whilst there is some indication that total IER and the array of partial IER protocols which have been developed may elicit distinct biological effects, our knowledge around this is limited as only a small number of rodent studies have directly addressed this.Ultimately, whilst much remains to be learned about IER, including its mechanisms of action and long-term efficacy, the positive findings to date serve to highlight promising avenues for future research.

Short‐term intermittent energy restriction interventions for weight management: a systematic review and meta‐analysis

“…Findings from this review illustrate that the cardiometabolic effects of IER were of interest and investigated in the primary studies; however, as a limited number of outcomes were repeatedly reported across studies, there was insufficient collective evidence to advocate any additional beneficial effects on health outcomes of weekly IER. This is consistent with the accumulative evidence on popular daily IER interventions , and future research is necessary. Although direct evidence from improvements in health risk factors was not investigated in this review, the mean weight loss reported in both interventions were of considerable magnitude (>5 kg) and thought to be associated with clinical health improvements in reducing health risk factors .…”

Intermittent fasting interventions for the treatment of overweight and obesity in adults aged 18 years and over: a systematic review protocol

“…In terms of the possible underlying biological benefits of intermittent fasting, there is some evidence, predominantly from animal studies, to demonstrate beneficial effects on weight loss and cardio-metabolic risk factors. Whilst the underpinning mechanistic evidence is limited, 6 there is some evidence to suggest that the benefits may be explained mechanistically through fat utilisation and nutritional stress (which can at least in part result in cellular repairs and functional optimisation) 7 that can result from fasting. However current NICE guidance on the treatment of adult obesity 5 does not recommend the routine use of very low calorie diets (VLCD) (defined as a hypocaloric diet of 800 or less kcal/day) for the treatment of adult obesity.…”

“…However other IF patterns are used such as alternate day fasting. 6 Despite the recent popularity of intermittent fasting 9 and associated weight loss claims, 10 the supporting evidence base in humans remains small and there is only one published systematic review 7 examining the health benefits of this approach, however the aim of this review was to examine the impact on wider health benefits, not specifically as a treatment approach for overweight and obesity, it also failed to provide a detailed methodology, and any meta analyses. .…”

Effect of Intermittent Energy Restriction on Flow Mediated Dilatation, a Measure of Endothelial Function: A Short Report

“…et al [ 5 ] concluded that weight loss can significantly improve fasting flow mediated dilatation (FMD) in adults; however, the effect may be influenced by subject characteristics, dietary composition and type of weight loss intervention. Intermittent energy restriction, a weight loss intervention gaining in popularity, has been shown to be as effective as the traditional moderate daily calorie restriction on weight loss, insulin sensitivity and cardio-metabolic biomarkers [ 6 , 7 , 8 , 9 , 10 , 11 ]. One such intermittent energy restriction strategy is the 5:2 diet, during which individuals consume a very low energy intake for two days per week (500 calories for women and 600 for men) combined with 5 days of habitual eating.…”