Effects of intermittent dieting with break periods on body composition and metabolic adaptation: a systematic review and meta-analysis

Context Intermittent dieting incorporated with break periods (INT-B) has recently been promoted as an alternative dietary approach for optimal weight management.Objective This study assessed the effectiveness of INT-B compared with that of conventional continuous energy restriction (CER) for improving body composition and attenuating metabolic adaptation.Data Sources A systematic search was conducted on 6 databases using all available records until July 2023.Data Extraction The extracted data included the lead author, year of publication, population characteristics, intervention protocols, duration, and adherence.Data Analysis Random-effects meta-analyses were conducted for within-group and between-group comparisons of anthropometric and metabolic outcomes. Subgroup moderator analysis was performed for the types of INT-B, intervention duration, and population characteristics.Results Of the 1469 records, 12 randomized trials (with 881 participants) were included. Within-group analyses demonstrated significant improvements in body mass, fat mass, body mass index, body fat percentage, and waist circumference following both INT-B and CER, with no significant group differences. However, resting metabolic rate (RMR) was significantly reduced following CER only. The compensatory reduction in RMR was significantly smaller following INT-B compared with CER, suggesting a lesser degree of metabolic adaptation. INT-B had a more significant effect on RMR retention in individuals with overweight/obesity compared with resistance-trained individuals.Conclusion This review provides up-to-date evidence for INT-B as a viable dietary strategy to improve body composition and attenuate metabolic adaptation.Systematic Review Registration PROSPERO registration no. CRD42023448959.