A new study suggests that people struggling to fit multiple exercise sessions into their week may still achieve meaningful fitness and fat-loss benefits by concentrating their workouts into one longer weekly session.
Researchers from the University of Hong Kong found that 75 minutes of high-intensity interval training (HIIT) performed once a week reduced body fat and waist circumference in adults with overweight and central obesity. The results were broadly comparable to completing the same total amount of exercise across three weekly sessions.
315 Adults Took Part in the Study
The randomized controlled trial involved 315 adults, divided equally into three groups. One group completed 75 minutes of HIIT once per week, another performed the same 75-minute total across three sessions, while a control group received health education without the exercise intervention.
After 16 weeks, both exercise groups showed significant reductions in total body fat compared with the control group.
Participants exercising once weekly recorded an average 2.6% reduction in total fat mass, compared with a 3.5% reduction among those exercising three times a week. Researchers found no statistically significant difference in fat-mass reduction between the two exercise schedules.
Waistlines and Fitness Also Improved
The benefits weren’t limited to overall body fat. Both HIIT groups experienced significant reductions in waist circumference and body-fat percentage, while cardiorespiratory fitness also improved.
The findings are particularly relevant because excess abdominal fat is associated with increased cardiometabolic health risks.
Separate 2026 research reviewing exercise strategies for people with overweight or obesity has also found HIIT effective at reducing visceral adipose tissue, although the optimal exercise program can vary between individuals.
Does This Mean One Workout Is All You Need?
Not necessarily. The study specifically examined adults with overweight and central obesity completing a structured 75-minute weekly HIIT program. It does not establish that any random once-a-week workout will eliminate belly fat, nor does it replace broader physical-activity and strength-training recommendations.
Instead, researchers say the findings support a “weekend warrior” approach as a practical alternative for people who struggle to exercise several times each week. No study-related adverse events were reported during the trial.
The takeaway is encouraging: the total amount and consistency of exercise may matter more than spreading workouts across many days when it comes to some fat-loss and fitness benefits.
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