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

Abstract Background 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. Methods Randomized 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). Results Eleven 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. Conclusions Both 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