Once-weekly high-intensity interval training rivals thrice-weekly workouts for fat loss, study finds

Research from the University of Hong Kong reveals that just one weekly 75-minute HIIT session can be nearly as effective at reducing body fat as three shorter workouts, offering a flexible exercise option for busy adults with abdominal obesity.

A single weekly session of high-intensity interval training may be enough to trim body fat almost as effectively as exercising three times a week, according to research from the University of Hong Kong published in Nature Communications. The findings add to evidence that the total amount of exercise can matter more than how it is distributed across the week, especially for adults with abdominal obesity.

The study compared people who completed one 75-minute treadmill interval session weekly with another group that split the same workload into three 25-minute workouts. Each session included four four-minute bursts of hard effort separated by recovery periods, and the once-weekly group finished the workout in three blocks with short breaks between them. After four months, both groups had significantly lower total body fat, with the single-session group reducing fat mass by about 2.6% and the three-session group by roughly 3.5%.

Although the fat-loss effect levelled off later in the study, waist measurements kept falling in both groups, suggesting continuing improvements in central fat. That is notable because visceral fat around the abdomen is closely associated with higher risks of heart disease, type 2 diabetes and other long-term health problems. The researchers said the results support a more flexible approach for people who struggle to fit exercise into a busy week.

The work sits alongside public-health advice from the US Centers for Disease Control and Prevention, which recommends at least 150 minutes of moderate aerobic activity a week, or 75 minutes of vigorous activity, plus muscle-strengthening exercise on two or more days. The CDC also says any amount of movement is better than none. Separately, the Hong Kong team’s lead researcher, Professor Parco Siu Ming-fai, said once-weekly interval training can be “a feasible and effective alternative” to more frequent exercise.