Abstract Context Intermittent fasting (IF) is a popular dietary strategy for the management of obesity and reducing visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT). However, the comparative efficacy of different IF modalities remains uncertain. Objective To evaluate the efficacy of IF interventions for reducing VAT and SAT in adults with overweight and obesity. Data Sources PubMed, Web of Science, and Scopus were searched from inception to July 2025 using key words related to fasting protocols and adipose tissue. Eligible studies were randomized trials of IF, including time-restricted eating (TRE), alternate-day fasting (ADF), or the 5:2 diet compared with controls (CON) or continuous caloric restriction (CR). Outcomes included changes in VAT and/or SAT in individuals with body mass index (BMI) ≥25 kg/m2. Data Extraction Two independent reviewers extracted data, with disagreements resolved by consensus. Data Analysis Twenty-four studies (n = 1930; ages 22–69 years; BMI : 27–40 kg/m2) were included, with 24 contributing to VAT and 8 to SAT analyses. Compared with CON, the 5:2 diet (standardized mean difference SMD: −0.54) and TRE (SMD: −0.44) led to greater reductions in VAT, whereas neither ADF nor CR had significantly larger effects. Compared with CR, TRE demonstrated a small reduction in VAT (SMD: −0.21); however, the difference was not statistically significant. Compared with CON, the 5:2 diet (SMD: −0.45) and TRE (SMD: −0.37) led to larger reductions in SAT, but ADF and CR did not lead to differential effects. No IF modality demonstrated superiority over CR for SAT. Conclusion Compared with CON, specific IF modalities—particularly the 5:2 diet and TRE—produce greater reductions in VAT and SAT. However, advantages over CR are limited, with only TRE approaching greater VAT reduction and no IF modality outperforming CR for SAT. IF may serve as an alternative to CR within a broader lifestyle approach, with adherence likely driving effectiveness. Systematic Review Registration PROSPERO registration no. CRD420251145598.
Khalafi et al. (Fri,) studied this question.