Completing just one weekly session of brisk interval walking may significantly reduce abdominal fat and improve cardiovascular fitness in adults with central obesity, according to new research from the School of Public Health at the LKS Faculty of Medicine, University of Hong Kong. The findings suggest that a single weekly workout may provide benefits comparable to exercising three times per week.
The study, published in Nature Communications, offers a more flexible alternative for people who struggle to meet conventional exercise recommendations. Researchers believe the findings could influence how clinicians advise patients with obesity who face barriers such as demanding work schedules, family responsibilities or limited free time.
Why abdominal fat matters
Central obesity, characterized by excess fat around the waist, is strongly associated with an increased risk of cardiovascular disease, type 2 diabetes and premature death. Visceral fat, which accumulates around internal organs, is considered particularly harmful because it contributes to chronic inflammation and metabolic dysfunction, even in people who may not appear severely overweight.
Current public health guidelines recommend at least 150 minutes of moderate-intensity physical activity or 75 minutes of vigorous exercise each week. However, many adults with obesity find it difficult to fit several exercise sessions into their weekly routine and maintain them over the long term.
How the study was conducted
Between September 2021 and September 2024, researchers from HKUMed conducted a randomized controlled trial involving 315 Chinese adults aged 18 years and older. All participants were overweight and met the criteria for central obesity based on waist circumference measurements.
The volunteers were randomly assigned to one of three groups. One group completed interval walking once a week, another performed the same type of exercise three times per week, while the control group received health education without structured exercise. The goal was to determine whether concentrating the entire weekly exercise volume into a single session could produce results comparable to a traditional multi-session program.
One workout versus three
Both exercise groups completed a total of 75 minutes of interval walking each week. Participants in the once-weekly group performed the entire 75-minute session under supervision, alternating periods of brisk walking with slower recovery intervals. Those in the three-times-per-week group divided the same total exercise time into three shorter supervised sessions.
Meanwhile, participants in the control group attended a 2.5-hour health education session every two weeks for four months. These classes covered topics including nutrition, healthy lifestyle habits and general wellness but did not include any structured exercise program.
Similar improvements in body fat and fitness
Researchers assessed body composition using dual-energy X-ray absorptiometry (DXA), a highly accurate method for measuring body fat and its distribution. Measurements were taken before the intervention, after 16 weeks and again at the 32-week follow-up.
After 16 weeks, participants in both interval walking groups experienced remarkably similar improvements. Compared with the control group, they reduced total body fat mass, lowered body fat percentage and decreased waist circumference. Both exercise programs also significantly improved cardiorespiratory fitness, an important predictor of long-term cardiovascular health and overall survival.
A practical option for busy adults
Lead investigator Professor Parco Siu Ming-fai said the findings suggest that once-weekly interval walking represents a realistic and effective option for many adults living with central obesity. He noted that lack of time consistently ranks among the most common reasons people fail to exercise regularly.
Rather than encouraging patients to commit to multiple exercise sessions every week, healthcare professionals may be able to recommend a single structured interval workout that still provides meaningful health benefits. This strategy could be especially valuable for individuals with long working hours, caregiving duties or other scheduling challenges.
What the findings mean
The study adds to growing evidence supporting the so-called “weekend warrior” approach, in which concentrating physical activity into one or two sessions each week may still provide substantial health benefits, provided the total weekly exercise volume is sufficient.
Researchers emphasize, however, that people should gradually build up to longer interval sessions and choose exercise intensities appropriate for their current fitness level.
Although exercising on several days each week may still be preferable for many individuals, the Hong Kong study suggests that even one carefully structured interval walking session can be an effective starting point for improving health. The researchers note that additional studies involving more diverse populations are needed, but the results already offer a practical alternative for people who find traditional exercise recommendations difficult to follow.
The trial was led by Professor Parco Siu Ming-fai, with Dr. Leung Chit-kay and Joshua Bernal serving as co-first authors. The research was funded by the Research Grants Council, the University Grants Committee of Hong Kong and the Seed Fund for Basic Research at the University of Hong Kong.
