Scientists in Hong Kong have discovered that a single weekly session of brisk interval walking may help overweight adults reduce belly fat and improve fitness almost as much as exercising three times a week.
The study, led by researchers from the School of Public Health at the LKS Faculty of Medicine of the University of Hong Kong, offers new hope for people who find it difficult to exercise regularly because of busy schedules.
The findings were published in the journal Nature Communications and could change the way doctors and health experts think about exercise programs for obesity.
Obesity is a long-term health condition caused by excess body fat. One of the most dangerous forms is central obesity, where fat collects around the abdomen.
This type of fat is strongly linked to serious illnesses including heart disease, type 2 diabetes, stroke, and metabolic disorders.
Health experts around the world encourage people to exercise regularly to lower these risks. Exercise improves heart health, burns calories, strengthens muscles, and helps the body use energy more efficiently. However, many people struggle to follow traditional fitness advice.
Standard recommendations often suggest doing exercise several times every week. For adults balancing work, study, childcare, and household responsibilities, this can feel difficult or impossible.
Researchers at HKUMed wanted to know whether fewer exercise sessions could still provide meaningful benefits if the total amount of exercise remained the same.
The team focused on interval training, a popular exercise method that alternates between short periods of harder activity and periods of slower recovery. Interval training is known to improve fitness efficiently and may burn more fat than steady exercise done at the same pace.
To test the idea, the researchers carried out a large clinical trial involving 315 adults in Hong Kong between 2021 and 2024. All participants were at least 18 years old, overweight, and had central obesity.
The participants were randomly placed into three groups. One group completed 75 minutes of brisk interval walking in a single weekly workout.
Another group completed the same total exercise time across three separate weekly sessions. The final group did not perform interval training and instead attended health education sessions every two weeks.
Scientists monitored the participants carefully throughout the study. They measured body fat, waist size, and cardiorespiratory fitness before the study began, after 16 weeks, and again after 32 weeks.
The researchers used advanced scanning technology called dual-energy X-ray absorptiometry to measure body fat accurately. This method is commonly used in medical research because it provides detailed information about body composition.
The results showed that both exercise groups experienced similar improvements after four months. Participants who exercised once weekly reduced their body fat and waist size to a similar degree as those who exercised three times weekly. Both groups also improved their fitness levels compared with the control group.
This finding surprised researchers because traditional exercise guidelines often emphasize frequent exercise sessions.
Professor Parco Siu Ming-fai, who led the study, said the results suggest that once-weekly interval training may be a practical and effective option for adults who cannot exercise multiple days every week.
The findings may be especially important for people who feel discouraged by demanding fitness programs. Some adults avoid exercise entirely because they believe they cannot meet strict schedules or daily workout goals.
The study suggests that health benefits may still be possible with a more flexible approach.
Researchers also noted that interval training can be very time efficient. Instead of requiring long periods of moderate exercise, interval walking increases intensity for short bursts, helping improve fitness in less time.
The study supports earlier research on so-called “weekend warriors,” people who complete most of their exercise during one or two days each week. Previous studies showed that weekend warriors could still gain heart health benefits, but evidence involving interval training had been limited until now.
The findings also raise interesting questions about future exercise guidelines. Public health recommendations may eventually become more flexible if future research confirms that lower-frequency exercise can still produce strong health improvements.
Still, the researchers caution that more studies are needed. The study only included Chinese adults with central obesity, so the results may not apply equally to all populations.
Scientists also want to study whether once-weekly interval training remains effective over many years and whether it can reduce long-term risks of heart disease and diabetes.
Even with these unanswered questions, the research offers an encouraging message for busy adults. People who struggle to fit exercise into crowded schedules may not need to give up on improving their health.
For many people, finding time for one longer workout each week may feel far more realistic than trying to exercise every few days.
If future studies continue supporting these findings, once-weekly interval walking could become a simple and practical exercise strategy for millions of adults worldwide.
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Source: The University of Hong Kong.
