A systematic review and meta‐analysis of interval training versus moderate‐intensity continuous training on body adiposity

Summary Interval training (including high‐intensity interval training [HIIT] and sprint interval training [SIT]) is promoted in both scientific and lay media as being a superior and time‐efficient method for fat loss compared with traditional moderate‐intensity continuous training (MICT). We evaluated the efficacy of HIIT/SIT when directly compared with MICT for the modulation of body adiposity. Databases were searched to 31 August 2016 for studies with exercise training interventions with minimum 4‐week duration. Meta‐analyses were conducted for within‐group and between‐group comparisons for total body fat percentage (%) and fat mass (kg). To investigate heterogeneity, we conducted sensitivity and meta‐regression analyses. Of the 6,074 studies netted, 31 were included. Within‐group analyses demonstrated reductions in total body fat (%) (HIIT/SIT: −1.26 [95% CI: −1.80; −0.72] and MICT: −1.48 [95% CI: −1.89; −1.06]) and fat mass (kg) (HIIT/SIT: −1.38 [95% CI: −1.99; −0.77] and MICT: −0.91 [95% CI: −1.45; −0.37]). There were no differences between HIIT/SIT and MICT for any body fat outcome. Analyses comparing MICT with HIIT/SIT protocols of lower time commitment and/or energy expenditure tended to favour MICT for total body fat reduction (p = 0.09). HIIT/SIT appears to provide similar benefits to MICT for body fat reduction, although not necessarily in a more time‐efficient manner. However, neither short‐term HIIT/SIT nor MICT produced clinically meaningful reductions in body fat.