This once-a-week workout may help cut belly fat, study shows
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- HKUMed researchers found in a four-month randomized trial of 315 adults with central obesity that 75 minutes of brisk interval walking in a single weekly session reduced total body fat mass, body fat percentage, and waist circumference comparably to spreading the same dose across three sessions.
- Both exercise groups — once-weekly and thrice-weekly — showed similar improvements at the 16-week assessment, with neither outperforming the other on fat loss or cardiorespiratory fitness compared with a control group receiving health-education sessions.
- Body composition was measured using dual-energy X-ray absorptiometry at baseline, 16 weeks (post-intervention), and 32 weeks (four-month follow-up), with the trial running from September 2021 to September 2024 in Hong Kong.
- Professor Parco Siu Ming-fai, Head of Division of Kinesiology at HKUMed's School of Public Health, led the study and said time constraints are "a primary barrier" for adults with central obesity, calling once-weekly training "a feasible and effective alternative" to high-frequency prescriptions.
- The findings were published in Nature Communications and were supported by Hong Kong's Research Grants Council (General Research Fund) and the HKU Seed Fund for Basic Research.
- Co-first authors Dr. Leung Chit-kay and Joshua D. Bernal, both of HKUMed's School of Public Health, helped conduct the trial alongside co-authors including Martin Gibala, a prominent interval-training researcher.
Why it matters: Traditional exercise guidance recommends interval training three days a week, yet the HKU trial showed comparable fat-loss and fitness benefits when the same 75-minute weekly dose was condensed into one session. For the roughly time-constrained adults with central obesity who abandon multi-day exercise routines — the population Siu's team explicitly cited — this peer-reviewed Nature Communications result gives clinicians a lower-burden alternative to prescribe without sacrificing measurable outcomes.
