Effect of alternate-day fasting on obesity and cardiometabolic risk: A systematic review and meta-analysis

Background & aims: Alternate-day fasting (ADF) is related to weight reduction, lowered risks of weight regain, and relative lean body mass preservation compared to continuous energy restriction. This meta-analysis aimed to assess the effects of ADF on obesity-related factors and cardiometabolic risk factors in adults.

Methods: Using PubMed, EMBASE, and Cochrane online databases, an electronic search was performed. Randomized controlled trials were investigated to evaluate ADF effects on body mass index (BMI), body weight (BW), waist circumference, body fat mass (FM), lean body mass, and cardiometabolic risk factors in adults aged ≥18 years. By utilizing a random-effects model, meta-analyses to assess weighted mean difference (WMD) with 95% confidence intervals (CIs) were performed for eight randomized controlled trials (total participants = 728).

Results: We observed significant effects of ADF for BMI (WMD -0.73 kg/m², 95% CI -1.13 to -0.34), FM (WMD -1.27 kg, 95% CI -2.09 to -0.46), and total cholesterol (WMD -8.14 mg/dL, 95% CI -14.59 to -1.69). Subgroup analyses indicated that significant intervention effects were observed for BMI, BW, FM, and total cholesterol when compared to the control, the participants were overweight, and the study duration was <6 months. ADF is effective in reducing waist circumference in adults aged ≥40 years with obesity. However, there was no difference between ADF and continuous energy restriction, time-restricted feeding, or control with regard to lean body mass.

Conclusions: Current evidence suggests that ADF effectively lowers BMI, BW, FM, and total cholesterol in adults with overweight within 6 months compared to the control.