HIIT Improves Cardiometabolic Markers in Adolescents with Obesity, but No Clear Edge Over Moderate Training

High-intensity interval training is associated with meaningful improvements in body composition, blood pressure, cardiorespiratory fitness and metabolic biomarkers in adolescents with obesity, according to a systematic review and meta-analysis published in Diabetology & Metabolic Syndrome. The analysis pooled 20 randomized controlled trials covering 964 adolescents aged 11 to 18 years, comparing high-intensity interval training, or HIIT, with no exercise, with moderate-intensity continuous training and, exploratorily, with other exercise and dietary strategies.

The pairwise meta-analysis, which pooled HIIT against all comparators combined, found that HIIT was associated with lower body mass index, with a standardized mean difference of −0.46, and a lower BMI z-score of −0.56, with a 95 percent confidence interval of −0.93 to −0.18. Body weight, body fat percentage, fat mass, systolic blood pressure, diastolic blood pressure, triglycerides, fasting insulin and insulin resistance measured by HOMA-IR all showed statistically significant reductions. Cardiorespiratory fitness improved markedly, with VO₂max rising by a standardized 0.94, and HDL cholesterol increased by 0.27. Fat-free mass, total cholesterol, LDL cholesterol and fasting glucose did not change significantly in the pooled pairwise estimates.

The most reliable contrasts came from direct network comparisons against no-exercise controls. Against inactive controls, HIIT was associated with a mean difference of −1.46 kg/m² in BMI, −3.92 kg in body weight, −1.72 percentage points in body fat, −1.13 mmHg in diastolic blood pressure, −4.23 mmHg in systolic blood pressure, −2.63 mg/dL in fasting glucose and −3.33 µIU/mL in fasting insulin. VO₂max increased by 2.95 mL/kg/min and HDL cholesterol by 4.70 mg/dL. These direct estimates form the primary evidence base of the review, because the underlying network of trials was star-shaped, meaning every trial connected to HIIT without closed loops that would allow robust indirect comparisons between other interventions.

Only two trials directly compared HIIT with moderate-intensity continuous training, commonly known as MICT. In those trials, HIIT produced a VO₂max gain of 2.43 mL/kg/min, with a 95 percent confidence interval of 0.70 to 4.16, suggesting a modest fitness advantage. However, pooled differences between HIIT and MICT in adiposity outcomes were small and not statistically significant. The authors concluded that evidence that HIIT is superior to MICT or to other interventions is insufficient, and that the findings do not establish superiority or time efficiency and should not be used alone to guide clinical recommendations.

Certainty in the pooled pairwise estimates was rated as low to moderate, while certainty in the network-derived contrasts was very low. The review used the Cochrane RoB 2 tool to assess risk of bias in the included randomized trials. Meta-regression, performed in JAMOVI, was restricted to exploratory univariable models in outcomes with at least 10 studies, and the authors explicitly stated that no moderator effects are claimed. Indirect comparisons between other interventions, and estimates based on a single trial, were treated as exploratory and were not interpreted.

The methodological caution matters because HIIT has been widely promoted as a time-efficient alternative to continuous moderate exercise, particularly for adolescents whose schedules and motivation often limit adherence to longer sessions. HIIT alternates short bursts of near-maximal effort with recovery periods, and mechanistically it is thought to drive greater acute metabolic stress, higher excess post-exercise oxygen consumption and stronger stimuli for mitochondrial and vascular adaptation than steady-state training. The new analysis supports real benefits in fitness and selected cardiometabolic markers, but it stops short of endorsing HIIT as the superior modality.

Adolescent obesity is increasing globally and is associated with early cardiometabolic risk, including elevated blood pressure, dyslipidemia and insulin resistance that can track into adulthood. Exercise is a cornerstone of management, yet the comparative effectiveness of different modalities has remained unclear. The included interventions spanned HIIT, moderate-intensity continuous training, sprint-based training and combined exercise or dietary approaches, reflecting the heterogeneous landscape of pediatric obesity trials. At least three of the 20 trials also enrolled adolescents with overweight alongside those with obesity, a detail the authors flagged when describing the population.

For clinicians and researchers, the practical takeaway is that HIIT can improve BMI, body weight, body fat, blood pressure, fasting insulin, HOMA-IR, VO₂max and HDL cholesterol in adolescents with obesity when compared with doing no structured exercise at all. Whether those gains exceed what moderate continuous training achieves remains an open question, with only two head-to-head trials available and very low certainty in any indirect ranking. The authors emphasized that their findings should be combined with other evidence, including dietary and behavioral interventions, rather than used alone to guide treatment decisions.

The review also illustrates the limits of network meta-analysis when the underlying evidence network lacks closed loops. Without trials that compare multiple interventions against each other in the same analysis, indirect rankings between, for example, HIIT and sprint-based training or combined dietary programs rest on assumptions that cannot be verified. The authors therefore confined their primary conclusions to direct HIIT comparisons and labeled everything else exploratory. Future randomized trials that directly compare HIIT with MICT and other modalities in adolescents with obesity, with adequate sample sizes and consistent outcome measurement, would be needed to establish whether the intensity advantage translates into superior cardiometabolic outcomes.

Subject of Research: Comparative effects of high-intensity interval training versus other exercise modalities on cardiometabolic markers in adolescents with obesity

Article Title: Optimizing obesity treatment in adolescent: a network meta-analysis and meta-regression of HIIT vs. other exercise modalities on cardiometabolic markers

Article References: Kesoema, T. A., Rachmawati, B., Tulaar, A. B. M., Susanto, H., Mulyadi, A., Tjandra, K. C., Stephani, E., de Ávila, V. K., & Nurkolis, F. (2026). Optimizing obesity treatment in adolescent: a network meta-analysis and meta-regression of HIIT vs. other exercise modalities on cardiometabolic markers. Diabetology & Metabolic Syndrome. https://doi.org/10.1186/s13098-026-02339-1

Image Credits: AI Generated

DOI: 10.1186/s13098-026-02339-1

Keywords: HIIT, adolescent obesity, meta-analysis, cardiometabolic risk, moderate-intensity continuous training, VO₂max, blood pressure, insulin resistance, body composition, randomized controlled trials, network meta-analysis, Diabetology & Metabolic Syndrome