Do intermittent diets provide physiological benefits over continuous diets for weight loss? A systematic review of clinical trials

Abstract

Energy restriction induces physiological effects that hinder further weight loss. Thus, deliberate periods of energy balance during weight loss interventions may attenuate these adaptive responses to energy restriction and thereby increase the efficiency of weight loss (i.e. the amount of weight or fat lost per unit of energy deficit). To address this possibility, we systematically searched MEDLINE, PreMEDLINE, PubMed and Cinahl and reviewed adaptive responses to energy restriction in 40 publications involving humans of any age or body mass index that had undergone a diet involving intermittent energy restriction, 12 with direct comparison to continuous energy restriction. Included publications needed to measure one or more of body weight, body mass index, or body composition before and at the end of energy restriction. 31 of the 40 publications involved 'intermittent fasting' of 1-7-day periods of severe energy restriction. While intermittent fasting appears to produce similar effects to continuous energy restriction to reduce body weight, fat mass, fat-free mass and improve glucose homeostasis, and may reduce appetite, it does not appear to attenuate other adaptive responses to energy restriction or improve weight loss efficiency, albeit most of the reviewed publications were not powered to assess these outcomes. Intermittent fasting thus represents a valid--albeit apparently not superior--option to continuous energy restriction for weight loss.

Control of energy expenditure in humans

“…However, although intermittent energy restriction consistently reduces body weight and adiposity, it does not seem to be superior to continuous energy restriction for weight loss. 36 Adaptive reduction of TEE is similar at both regimens of energy restriction.…”

Impact of intermittent fasting on health and disease processes

“…The most studied IF regimen has been alternate days of 70% CR, a modified form of ADF. Most studies of ADF summarized in recent reviews show benefits in terms of reductions in weight (−3 to −7%), body fat (3 −5.5 kg), total serum cholesterol(−10 to −21%) and triglycerides (−14 to −42) (Tinsley and La Bounty, 2015), as well as improvements in glucose homeostasis (Seimon et al, 2015). However the lack of a CER comparator in most of these studies means again, we cannot determine if these effects are a function of the overall energy restriction/weight loss or a specific effect of the IF regimen.…”

Metabolic Effects of Intermittent Fasting

“…Reviews and meta-analyses have compared the efficacy of fasting regimens with continuous energy restriction (6,44,48,91,107). The authors of these publications unanimously report that, given the current state of the evidence, the overall metabolic benefits of fasting regimens are not superior to those of continuous energy restriction.…”