The study, conducted by researchers at the School of Public Health of the LKS Faculty of Medicine at the University of Hong Kong (HKUMed), provides strong scientific evidence supporting once-weekly brisk interval walking as a practical and effective exercise option, particularly for adults with central obesity who face time constraints.

The findings have been published in Nature Communications.

A practical approach to tackling obesity

Obesity is a chronic condition marked by excessive fat accumulation that increases the risk of serious health problems, including cardiovascular disease, metabolic disorders, and premature death. Fat concentrated around the abdomen, known as central obesity, is particularly harmful.

Although regular physical activity plays a key role in managing obesity and improving overall health, maintaining consistent exercise remains a challenge for many people, especially those with obesity.

Interval training, which alternates between periods of vigorous exercise and lower-intensity recovery, has emerged as a time-efficient way to reduce total body fat and harmful visceral fat compared with traditional moderate-intensity continuous exercise. However, most exercise guidelines recommend interval training three times a week, a schedule that may be difficult for people with demanding work or family commitments.

Previous research has suggested that the "weekend warrior" exercise pattern—condensing weekly physical activity into one or two days—can provide health benefits. However, evidence on whether interval training performed in this manner is equally effective has remained limited.

Professor Parco Siu Ming-fai, Professor and Head of the Division of Kinesiology at HKUMed's School of Public Health, said it was important to determine whether once-weekly interval training could match the effectiveness of the conventional three-times-a-week approach while offering a more practical alternative.

Comparable benefits with fewer sessions

Between September 2021 and September 2024, the HKUMed research team conducted a randomized controlled trial involving 315 Chinese adults aged 18 years and older who were overweight and had central obesity.

Participants were randomly assigned to one of three groups: a once-weekly interval training group, a thrice-weekly interval training group, or a control group.

The control group attended a 2.5-hour health education session every two weeks for four months. Participants in both exercise groups completed the same total amount of exercise—75 minutes of interval training per week—either in a single weekly session or divided into three sessions.

Researchers assessed body fat using dual-energy X-ray absorptiometry (DXA) scans at baseline, after the 16-week intervention, and again at a 32-week follow-up.

The results showed that after 16 weeks, both the once-weekly and thrice-weekly interval training programmes produced similar reductions in total body fat, body fat percentage, and waist circumference, while also significantly improving cardiorespiratory fitness compared with the control group.

"While thrice-weekly interval training remains a commonly recommended strategy for managing excess adiposity, our findings demonstrate that once-weekly interval training delivers comparable benefits and represents a practical exercise option," Professor Siu said.

"For many adults with central obesity who struggle to balance work, studies, family responsibilities, and other commitments, lack of time is one of the biggest barriers to exercising several days a week."

He added that rather than relying solely on high-frequency exercise prescriptions, healthcare professionals could also consider once-weekly interval training as a feasible and effective alternative for reducing excess body fat.