Intermittent versus continuous energy restriction on weight loss and cardiometabolic outcomes: a systematic review and meta-analysis of randomized controlled trials

Ezio Ghigo,Simona Bo,Laura Soldati,Giovannino Ciccone,Andrea Evangelista,Fabrizio Pasanisi,Franco Contaldo,Lidia Santarpia,Valentina Ponzo,Iolanda Cioffi

doi:10.1186/s12967-018-1748-4

Abstract

BackgroundThis systematic review and meta-analysis summarized the most recent evidence on the efficacy of intermittent energy restriction (IER) versus continuous energy restriction on weight-loss, body composition, blood pressure and other cardiometabolic risk factors.MethodsRandomized controlled trials were systematically searched from MEDLINE, Cochrane Library, TRIP databases, EMBASE and CINAHL until May 2018. Effect sizes were expressed as weighted mean difference (WMD) and 95% confidence intervals (CI).ResultsEleven trials were included (duration range 8–24 weeks). All selected intermittent regimens provided ≤ 25% of daily energy needs on “fast” days but differed for type of regimen (5:2 or other regimens) and/or dietary instructions given on the “feed” days (ad libitum energy versus balanced energy consumption). The intermittent approach determined a comparable weight-loss (WMD: − 0.61 kg; 95% CI − 1.70 to 0.47; p = 0.87) or percent weight loss (WMD: − 0.38%, − 1.16 to 0.40; p = 0.34) when compared to the continuous approach. A slight reduction in fasting insulin concentrations was evident with IER regimens (WMD = − 0.89 µU/mL; − 1.56 to − 0.22; p = 0.009), but the clinical relevance of this result is uncertain. No between-arms differences in the other variables were found.ConclusionsBoth intermittent and continuous energy restriction achieved a comparable effect in promoting weight-loss and metabolic improvements. Long-term trials are needed to draw definitive conclusions.

Highlights

This systematic review and meta-analysis summarized the most recent evidence on the efficacy of intermittent energy restriction (IER) versus continuous energy restriction on weight-loss, body composition, blood pressure and other cardiometabolic risk factors
After further analysis and quality assessment, a total of 11 studies were selected for the systematic review and meta-analysis (Fig. 1)
Data relative to participants involved in exercise-only arms [19] or in high-protein dietary intervention [20] were not considered, because not pertinent to the aims of the study

Summary

Introduction

This systematic review and meta-analysis summarized the most recent evidence on the efficacy of intermittent energy restriction (IER) versus continuous energy restriction on weight-loss, body composition, blood pressure and other cardiometabolic risk factors. The time-restricted feeding [2, 6,7,8,9] and the very-lowcalorie or energy diets [2, 3] are other types of dietary interventions which were often included in previous systematic reviews and meta-analyses on IER. In the former, individuals are allowed to eat within a specific range of time, every day there is a period without food intake, varying from 12 to 21 h [10,11,12] (i.e. the Muslim Ramadan). There is no daily intermittency in a very-low-calorie-diet, the overall energy intake may be similar to those of the IER regimens [13]

Methods

Results

Conclusion