A systematic review, meta-analysis, and meta-regression of the impact of diurnal intermittent fasting during Ramadan on body weight in healthy subjects aged 16 years and above

Purpose Studies on the effect of Ramadan diurnal intermittent fasting (RDIF) on body weight have yielded conflicting results. Therefore, we conducted a systematic review and meta-analysis to estimate the effect size of body weight changes in healthy, non-athletic Muslims practicing Ramadan fasting, and to assess the effect of covariates such as age, sex, fasting time duration, season, and country, using subgroup analysis, and meta-regression. Covariate adjustments were performed to explain the variability of weight change in response to Ramadan fasting. Methods CINAHL, Cochrane, EBSCOhost, EMBASE, Google Scholar, ProQuest Medical, PubMed/MEDLINE, ScienceDirect, Scopus, and Web of Science databases were searched from date of inception in 1950 to the end of August 2019. Results Eighty-five studies, conducted in 25 countries during 1982–2019, were identified. RDIF yielded a significant, but small reduction in body weight ( K = 85, number of subjects, N = 4176 (aged 16–80 years), Hedges’ g =− 0.360, 95% confidence interval (CI) − 0.405 to − 0.315, I 2 = 45.6%), this effect size translates into difference in means of − 1.022 kg (95% CI − 1.164 kg to − 0.880 kg). Regression analysis for moderator covariates revealed that fasting time (min/day) is a significant ( P