One weekly workout is enough to reduce belly fat – Earth.com
08-04-2026
You may only need one workout a week to lose body fat
BySanjana Gajbhiye
Earth.com staff writer
Finding time to exercise is one of the biggest challenges many adults face. Health experts often recommend working out several times a week, but busy schedules can make that difficult
A new study offers encouraging news for people with extra belly fat
Professor Parco Siu, who led the trial at the University of Hong Kong (HKU), found that one longer interval training session each week reduced body fat by almost the same amount as three shorter weekly sessions
While the improvements were modest, the results suggest that even people with limited free time can still benefit from regular exercise
Belly fat increases health risks
Fat stored around the belly is more dangerous than fat carried elsewhere. It raises the odds of heart disease, diabetes, and dying early
In a review of more than 2.5 million people, every 4 inches (10 cm) added to the waist came with an 11 percent higher risk of early death. So reducing belly fat is worth the effort
The hard part is getting people to train often enough to lose it. Time is the barrier most people name
Workout schedules for belly fat
The team recruited 315 adults who were overweight and carried too much fat around the waist. Their average age was 48, and close to two-thirds were women
To qualify, men needed a waist of at least 35 inches (90 cm) and women at least 31.5 inches (80 cm). All had been inactive for months before the trial
Everyone was sorted at random into three groups: one weekly interval session, three shorter sessions, or health classes with no exercise
The class group met every two weeks for health talks and did no workouts
Equal workout time for belly fat
The two exercise groups each did 75 minutes of treadmill work a week, hard for four minutes, then easy for three
That 75 minutes is the weekly amount of vigorous activity that the World Health Organization (WHO) recommends. The once-a-week group did all of it in one visit
The team included Martin Gibala of McMaster University, a longtime researcher of short, intense workouts
The trial was registered with ClinicalTrials.gov before it began, and no exercise-related harms were reported
What one session looked like
The single weekly session was not quick. Participants did three 25-minute interval blocks back to back, resting 15 to 30 minutes between them
Each block held four 4-minute pushes at 85 to 95 percent of peak heart rate, broken up by three minutes of easy walking. The first four weeks eased people in before the full load began
The time saved showed up outside the gym. Counting travel and exercise together, the once-a-week group spent about 4.5 hours a week, against 8.2 hours for the three-times group
One session, less body fat
After 16 weeks, both exercise groups had lost body fat while the class group had not. The once-a-week group dropped about 1.8 pounds (0.8 kg), and the three-times group about 2.2 pounds (1.0 kg)
The difference between the two exercise groups was too small to count as real. Both trimmed their waists by close to an inch, and the class group did not
In relative terms, the once-a-week group lost 2.6 percent of its fat and the three-times group 3.5 percent. Almost everyone stayed the course, with 94 percent finishing the 16 weeks
“While thrice-weekly interval training remains a commonly recommended approach for the therapeutic management of excess adiposity, our findings show that once-weekly interval training offers similar benefits and represents a practical exercise strategy,” said Professor Siu
“For many adults with central obesity who struggle to balance work, study, family and other commitments, time constraints are a primary barrier to exercising multiple days per week.”
Belly fat workout improved fitness
Both exercise groups also improved their aerobic fitness, a measure of how well the body uses oxygen during hard effort
The once-a-week group gained about 6 percent, and the three-times group about 11 percent
Here the two schedules differed. After adjusting for age, sex, and other factors, the three-times group was clearly fitter
Only the three-times group lost a meaningful amount of body weight and trimmed its body-mass index. Blood pressure, blood sugar, and cholesterol did not move in any group
Most participants started in a healthy range for those markers. That left little room to improve
Four months later
The exercise stopped at 16 weeks, and the groups were measured again four months on
The trial leaves real questions open. No one yet knows whether a fat loss this modest lowers the long-term risk of heart disease or early death
The people studied were Chinese adults who were fairly healthy to start with. The results may not hold for those with diabetes or other conditions, and the trial was not built to prove that one session truly equals three
“Instead of relying solely on high frequency exercise prescriptions, once weekly interval training can be considered a feasible and effective alternative,” noted Professor Siu
For anyone who cannot fit in several exercise days, that single weekly session may simply be the one they keep
The study is published in the journal Nature Communications
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