Abstract
BACKGROUND: The relative effectiveness of sprint interval training (SIT) versus moderate-intensity continuous training (MICT) for fat loss remains debated, with significant heterogeneity in published findings. This study aimed to compare their effects on body composition and to identify key moderators of these effects through advanced meta-regression techniques. METHODS: We conducted a systematic search of major scientific databases up to March 1, 2025, for randomised controlled trials directly comparing SIT and MICT. A primary random-effects meta-analysis was performed, followed by a series of single- and multivariable meta-regressions and interaction analyses to investigate the independent effects of various “dose” metrics (e.g., weekly sprint time, intervention duration), participant population, and protocol characteristics. RESULTS: Twenty-three studies were included. The primary analysis revealed no significant overall difference between SIT and MICT for changes in total body fat mass (SMD = -0.11, 95% CI: −0.30 to 0.08) or body fat percentage (SMD = -0.13, 95% CI: −0.30 to 0.05). However, the multivariable meta-regression uncovered a significant, independent dose-response relationship: increasing the total weekly sprint time was associated with a greater reduction in absolute body fat mass, but not body fat percentage. Interaction analyses further revealed this dose-dependent effect is strikingly more pronounced in normal-weight individuals and is significantly amplified when using active recovery protocols. CONCLUSIONS: The pooled null effect between SIT and MICT masks a crucial, predictable reality. The efficacy of SIT is not uniform but is a function of specific training and population variables. Its superiority for reducing absolute body fat mass is contingent on sufficient weekly sprint volume, a benefit that is most scalable in normal-weight individuals and enhanced by active recovery. The discrepancy between body fat mass and fat percentage outcomes suggests SIT may better preserve lean body mass. These findings advocate for a shift from a generic comparison to a personalized, dose- and context-aware approach to exercise prescription for public health. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-025-25802-6.