Exercise to Keep Weight Off: What the Evidence Says

The argument that exercise does not matter for weight loss gets a lot of attention right now, and it is built on a real finding. Your body partly compensates for the energy you burn, and one workout is easy to out-eat. We covered that side of the story in does exercise make you hungrier and does cardio help you lose weight. But losing weight and keeping it off are two different problems. Most people who lose weight regain much of it, and the evidence on that second problem points in a clear direction: activity is one of the strongest things that separates people who keep weight off from people who do not.

Does exercise matter if diet does the losing?

The most striking evidence comes from an unlikely place: the contestants of the television show "The Biggest Loser." Researchers at the National Institutes of Health measured 14 of them six years after the competition, using doubly labeled water to track both what they ate and what they burned (Kerns et al., 2017). The people who kept off the most weight, 24.9% of their starting weight on average, had increased their physical activity by 160%. Those who regained everything had increased it by only 34%.

What did not differ is just as telling. Changes in energy intake were almost identical between maintainers and regainers, about 8.7% and 7.4% lower than before the competition. Weight regain tracked closely with changes in physical activity (r = -0.82) and not with changes in intake. That is only 14 people at an extreme starting point, so treat it as a signal rather than a rule. In this group, the people who held their loss were not those who ate least, but those who moved most.

How much activity do people who keep weight off actually do?

A University of Colorado study measured 25 people who had kept off at least 13.6 kg for at least a year (Ostendorf et al., 2019). On average they had maintained a loss of 26.2 kg for about nine years. They were compared with never-heavy people of similar current weight and with people whose weight matched the maintainers' starting point.

The maintainers spent 812 kcal a day on physical activity, against 621 kcal in the normal-weight group and 637 kcal in the group with obesity. As a result, their total daily energy expenditure was close to that of people far heavier than they were. The authors' reading is that maintainers rely on a high level of activity to stay in energy balance at a lower body weight.

This is a snapshot of a small, self-selected group. It cannot prove that activity caused the maintenance; people who keep weight off may simply be people who like to move. It does show what successful maintenance tends to look like, and it is not dieting alone.

What happens when you stop a GLP-1 medication?

GLP-1 medications such as semaglutide and tirzepatide produce larger losses than any lifestyle program, and they have made the maintenance question more urgent. In the STEP 1 trial extension, people lost 17.3% of their body weight over 68 weeks on semaglutide. When the drug and the lifestyle program stopped, they regained 11.6 percentage points of that loss within a year, about two-thirds of it, and most cardiometabolic improvements drifted back toward baseline (Wilding et al., 2022).

The tirzepatide data show the same pattern. In SURMOUNT-4, participants lost 20.9% of their weight over 36 weeks. Those switched to placebo regained 14.0% over the next year, while those who stayed on the drug lost a further 5.5% (Aronne et al., 2024). For many people, staying on the medication is the right plan. But many stop, for reasons of cost, side effects or preference, and the question is what protects the result when they do.

Can exercise protect the weight you lost?

A Copenhagen trial tested this directly (Lundgren et al., 2021). 195 adults with obesity first lost an average of 13.1 kg on an eight-week low-calorie diet. They were then assigned for one year to supervised moderate-to-vigorous exercise, the GLP-1 medication liraglutide, both combined, or placebo. Compared with placebo, the exercise group weighed 4.1 kg less at one year, the liraglutide group 6.8 kg less and the combination group 9.5 kg less. The combination cut body-fat percentage by 3.9 points, about twice either treatment alone, and it was the only arm that improved blood sugar control, insulin sensitivity and cardiorespiratory fitness.

The more telling result came a year after all treatment stopped (Jensen et al., 2024). In the year after the program ended, people who stopped liraglutide regained 6.0 kg more than people who stopped exercising under supervision. Those who had exercised were 3.7 times as likely as the placebo group to still be at least 10% below their starting weight. People who had received the combination ended the follow-up 5.1 kg lighter than those who had received liraglutide alone.

The limitations matter. Only 109 of the 195 original participants returned for that final visit, the exercise program was supervised, which few people have at home, and the trial was funded in part by the Novo Nordisk Foundation. It also tested liraglutide, an older and weaker drug than semaglutide or tirzepatide. Nobody has yet shown the same protection after stopping the newer drugs.

How big is the effect, honestly?

Smaller than the Copenhagen trial alone suggests. A 2026 meta-analysis pooled 11 randomized trials with 568 participants who had already lost weight (Wang et al., 2026). Exercise during the maintenance phase reduced weight regain by 2.81 kg on average, and the result was consistent across trials. The effect on fat mass was inconclusive. The authors call the benefit small but consistent.

That is the fair summary. Exercise will not stop regain on its own, and individual responses vary widely. What it offers is a reliable nudge in the right direction, plus benefits the scale does not show: in the Copenhagen trial, only the arm that combined exercise with liraglutide improved cardiorespiratory fitness, and VO₂max, the measure of that fitness, is one of the strongest predictors of how long you live.

What does this mean for your training?

The maintainers in these studies were not doing anything exotic. They were consistently more active than their peers, every week, for years. That makes the exercise you will keep doing more important than the exercise that burns the most calories in one session.

It also helps to be clear about what different kinds of training do. Short, hard sessions such as REHIT (Reduced Exertion High-Intensity Interval Training), the five-minute protocol on the CAROL Bike, are designed to raise VO₂max in very little time. They are not designed to burn hundreds of calories, and five minutes will not replace the daily activity these maintainers relied on. The two work together: brief intervals to build and protect fitness, and more everyday movement, such as walking, longer easy rides and active hobbies, to keep total energy expenditure high.

If you take a GLP-1 medication, or plan to stop one, make that decision with your prescriber. This article is not medical advice. The evidence here is a reason to build an exercise habit while you are on the medication, so it is already in place if treatment ends.

The bottom line

Diet does most of the work of losing weight. Activity does a large share of the work of keeping it off. People who maintain big losses for years burn far more energy through activity than their peers, and in a randomized trial, people who stopped a supervised exercise program held their weight a year later while people who stopped liraglutide regained 6.0 kg more. Across 11 trials, the average benefit is modest, about 2.8 kg less regain, and results vary from person to person. Start the habit early, choose exercise you will keep doing, and count fitness gains as part of the result, not just the number on the scale.