Effects of high-intensity interval training versus continuous aerobic training on body weight, body mass index, and body fat percentage in youth with overweight or obesity: a systematic review and meta-analysis.

BACKGROUND

Overweight and obesity in youth are associated with substantial short- and long-term health burdens, and structured exercise is a central component of management. Whether HIIT offers greater improvements in body composition than continuous aerobic training remains uncertain.

METHODS

This systematic review and meta-analysis followed PRISMA 2020. PubMed, Embase, Web of Science, CNKI, Wanfang, and VIP were searched from inception to December 31, 2024 for randomized trials directly comparing high-intensity interval-based training, including high-intensity interval exercise and sprint-interval protocols, with continuous aerobic training in youth with overweight or obesity. Outcomes were body weight, BMI, and body fat percentage. Risk of bias was assessed with RoB 2. Random-effects models with REML estimation and modified Hartung-Knapp inference generated mean differences (MDs) and 95% confidence intervals (CIs). Sensitivity, subgroup, and small-study-effect analyses were also performed.

RESULTS

Fourteen independent randomized trials were included. For body weight, 13 trials involving 409 participants showed no statistically significant difference between HIIT and continuous aerobic training (MD = -0.37 kg, 95% CI -0.89 to 0.15; P = 0.146; I 2 = 0%). For BMI, 14 trials involving 432 participants also showed no significant difference (MD = -0.14 kg/m2, 95% CI -0.31 to 0.02; P = 0.089; I 2 = 0%). For body fat percentage, 11 trials involving 331 participants showed no significant difference (MD = -0.33 percentage points, 95% CI -1.33 to 0.67; P = 0.481), with moderate-to-substantial heterogeneity (I 2 = 60.3%). Sensitivity analyses did not materially alter the findings, and subgroup analyses did not identify reliable effect modification by weekly frequency, intervention duration, or mean age. Egger's tests did not detect statistically significant small-study effects. One trial was at low overall risk of bias, whereas 13 raised some concerns.

CONCLUSION

Randomized evidence identified through December 31, 2024 does not show that HIIT provides greater reductions in body weight, BMI, or body fat percentage than continuous aerobic training. HIIT may be considered an alternative exercise format, but the limited evidence base and heterogeneity in body fat outcomes warrant cautious interpretation.