Abstract
Obesity is a global public health crisis that is aggravated and mirrored by the high prevalence of physical inactivity. This single-center, assessor-blinded, three-group, randomized controlled trial in Hong Kong examined the therapeutic value of high-intensity interval training (HIIT) delivered in one session per week via a “weekend warrior” approach versus three sessions per week for reducing body adiposity in adults with overweight and central obesity. Participants were randomly assigned in a 1:1:1 ratio to once-weekly HIIT (H1), thrice-weekly HIIT (H3), and control (CON) groups (n = 105 per group). The interventions lasted for 16 weeks. The HIIT groups performed a total of 75 minutes of HIIT per week (either in one session or three sessions), while the control group received biweekly health education classes. Outcomes were assessed at baseline, week 16, and week 32. The primary outcome was the change in total body fat mass from baseline to week 16. Secondary outcomes were reported in the main text. Compared to CON at week 16, both HIIT groups showed decreased fat mass (adjusted mean differences: H1 vs. CON: −0.8 kg [95% CI: −1.4 to −0.2], P = 0.0107; H3 vs. CON: −1.0 kg [95% CI: −1.6 to −0.5], P = 0.0003). No study-related adverse events were reported. Here, we show that HIIT, performed once- or thrice-weekly, is safe and reduces fat mass in adults with overweight and central obesity. Trial Registration: ClinicalTrials.gov identifier: NCT04887454.
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Data availability
The de-identified participant data generated in this study have not been publicly deposited to ensure participant confidentiality. The de-identified data, including study protocol and statistical analysis plan, are available under restricted access for privacy reasons and will be shared beginning 3 months and ending 5 years after publication of this article. Data will be shared with researchers who provide a methodologically sound proposal with achievable aims. Proposals should be directed to pmsiu@hku.hk, and those requesting access to the data will need to sign a data access agreement.
Code availability
Analyses were conducted on SAS OnDemand for Academics (SAS Institute, Engine V9) using standard syntax. No custom code was generated for the present analyses.
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Acknowledgements
The authors would like to thank all of the participants in the study, the fitness instructors (Mr. Tang Wai Hung and Mr. Fan Ka Tung), and the assessment technicians. This study is supported by the General Research Fund of Research Grants Council (RGC), Hong Kong University Grants Committee (project numbers: 17105920, 17110722, and 17112223), and the Seed Fund for Basic Research of the University of Hong Kong, which were awarded to P.M. Siu. The funders had no role in the design, data collection, data analysis, and reporting of this study.
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P.M.S. designed and conceptualized the study. P.M.S., D.Y.F., D.K.C., H.H.N., C.H.L., P.S.Y., S.H.W., and M.G. were involved in funding acquisition. P.M.S., C.K.L., J.B., and F.R. oversaw the execution of this study. P.M.S., C.K.L., and J.B. wrote and edited the manuscript. A.P.Y. and D.Y.F. provided statistical expertise. P.M.S., C.K.L., J.B., A.P.Y., F.R., B.T.T., D.Y.F., D.K.C., H.H.N., C.H.L., P.S.Y., S.H.W., and M.G. contributed to the critical revision of the article for intellectual content and gave final approval to its content.
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Siu, P.M., Leung, C.K., Bernal, J.D.K. et al. Once and thrice weekly interval training in adults with central obesity: a randomized controlled trial. Nat Commun (2026). https://doi.org/10.1038/s41467-025-68149-7
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DOI: https://doi.org/10.1038/s41467-025-68149-7
