ByDaniella Gray
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Finding time to exercise is one of the biggest barriers people face when trying to lose weight
But new research suggests that when it comes to reducing belly fat, fitting all your weekly workouts into a single session may be more effective than many people think
A study, published in Nature Communications, found that adults with overweight and central obesity (meaning excess fat around the abdomen) were able to reduce body fat and waist size whether they completed their weekly exercise in a single session or spread it across multiple workouts
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Researchers in Hong Kong recruited 315 inactive adults with overweight and central obesity and randomly assigned them to one of three groups
One group completed 75 minutes of high-intensity interval training (HIIT) in a single weekly session, while another completed the same amount of HIIT divided into three weekly workouts
A third control group received health education classes but did not participate in the exercise program
The intervention lasted 16 weeks, with participants assessed before and after the program
The primary goal was to determine whether concentrating exercise into a single “weekend warrior” session could be as effective for fat loss as spreading it across the week
Compared with the control group, participants in both exercise groups reduced their body fat mass
Those who completed one workout per week reduced fat mass by an average of 0.8 kilograms, while those exercising three times per week reduced fat mass by around 1 kilogram
The difference between the two exercise groups was not considered significant
Eduardo Matta Mello Portugal, Ph.D., an associate professor in exercise psychophysiology and neuroscience who was not involved in the research, told Newsweekthat the findings are encouraging for busy adults who struggle to fit multiple workouts into their schedule
“Current evidence suggests that people who follow a ‘weekend warrior’ pattern, performing the recommended amount of physical activity in one or two sessions per week, can still obtain important health benefits,” he said
Portugal noted that previous research has linked this approach to lower risks of cardiovascular disease and premature death compared with remaining inactive
Waist circumference, a key measure of abdominal fat, also decreased in both exercise groups, suggesting that the frequency of training sessions was less important than completing the overall exercise volume
There was, however, one notable difference between the groups. Participants who exercised three times a week experienced greater improvements in cardiorespiratory fitness than those who completed all their exercise in a single session
Portugal said the study provides evidence that people can achieve meaningful improvements even if they are only able to exercise once a week
However, he cautioned against viewing a single weekly workout as the ideal approach for everyone
“If someone only has time to exercise once a week, one session is certainly much better than doing nothing at all,” Portugal said. “However, for someone who is sedentary and already has a negative relationship with exercise… I would not make exercise intensity the first priority.”
People who have exercised regularly for years and are temporarily constrained by work or family commitments may be well suited to a weekend warrior routine
“Ultimately, exercise prescription should not focus only on what produces the greatest physiological adaptation in the short term,” Portugal said
“It should also consider what people are most likely to continue doing over the long term,” he said. “For public health, the best exercise program is not necessarily the most intense one—it is the one that people will still be doing years from now.”
Reference
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 Commun17, 1410 (2026). https://doi.org/10.1038/s41467-025-68149-7
Contact Newsweek editors on this story: Kara Dolman and Emma Lee-Sang
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