One HIIT Workout a Week May Help You Lose Fat

A daily workout habit sounds great until you’re the one trying to build it from scratch. New research offers a more realistic entry point: a single weekly high-intensity interval training (HIIT) session may be enough to produce meaningful fat loss over time.^[1]

What the study found

Researchers publishing in Nature Communications enrolled 315 adults in a 32-week exercise program and split them into three groups. One group did a single 75-minute HIIT session per week. A second group did the same total 75 minutes of HIIT, spread across three shorter sessions. A third, control group attended biweekly health education classes instead of exercising. By the end of the study, both HIIT groups showed meaningful reductions in body fat and waist circumference compared to the control group — and it didn’t matter much whether the 75 minutes came in one sitting or three.^[2]

Why that matters

“I think the major takeaway from this study is that whether you only have time to exercise once a week or three times a week, adding HIIT workouts can produce meaningful improvements in total body fat and waist circumference,” says Anna Di, D.C., a corrective exercise specialist and chiropractor at UNITY Chiropractic Wellness in New York City. “That’s encouraging because a lot of people think that if they can’t work out several days a week, it’s not even worth trying. This study suggests that doing something is definitely better than doing nothing.”

Patricia Greaves, C.P.T., a certified fitness trainer and founder of StrongHer Personal Training, points to consistency as the real variable. “Consistency matters more than trying to overcommit to exercising four to five times a week and giving up when adherence becomes too difficult,” she says.

Beyond fat loss

HIIT’s benefits extend past body composition. “Studies show HIIT can improve cardiovascular fitness, improve blood sugar control, and support your muscles’ ability to produce energy more efficiently. It is also more effective at burning calories in less time than steady-state cardio,” Greaves says. Adding resistance work into a HIIT session can also help preserve lean muscle mass — a meaningful advantage for anyone trying to lose fat without losing strength.

Who should be cautious

HIIT isn’t the right starting point for everyone. Greaves warns people with unmanaged high blood pressure, cardiovascular disease, or orthopedic limitations — or who aren’t used to regular exercise — against jumping into vigorous interval training without checking with a doctor first. She also notes that women in perimenopause or menopause who are already dealing with poor sleep may find that too much high-intensity work without adequate recovery leaves them more fatigued, not less.

The takeaway

If a daily workout habit has never stuck, this is permission to start smaller: one focused 75-minute HIIT session a week — or three 25-minute sessions if that fits your schedule better — is a legitimate, research-backed starting point for fat loss, not a consolation prize.

References

[1] “Scientists Say This Once-a-Week Workout May Promote Fat Loss,” Prevention, 2026. Commentary from Anna Di, D.C., and Patricia Greaves, C.P.T., on a 32-week HIIT frequency study. Read the source article. ↑︎

[2] Study on HIIT frequency and body fat mass, 315 adults, 32-week intervention. Nature Communications, 2026. Read the study. ↑︎

Kurt Greiner

Kurt is a digital strategist and IT professional blending emerging technology with practical application to help businesses and individuals streamline their digital presence. His current work focuses on the intersection of intentional living and technological resilience, exploring how individuals can leverage modern tools to navigate the second half of life with purpose.