There’s no such thing as a free lunch when it comes to losing weight with Ozempic and similar drugs. Research published this week finds that people who stop taking GLP-1 therapy tend to quickly experience a complication familiar to anyone who’s fallen off their diet.

Scientists at the University of Oxford examined dozens of studies following people after they discontinued obesity medication. Former users typically regained almost a pound every month, the researchers found, and they regained weight faster than people who shed their weight through lifestyle changes alone. More alarmingly, the rate of weight regain was even higher for people who stopped taking the latest GLP-1 drugs on the market, semaglutide and tirzepatide.

“These findings suggest caution in short term use of these drugs without a more comprehensive approach to weight management,” the authors wrote in their paper, published Wednesday in The BMJ.

Failure to maintain

GLP-1 medications like semaglutide (the active ingredient in Ozempic and Wegovy) have greatly improved the landscape of obesity treatment in recent years. Trials have consistently shown that these drugs are more effective at helping people lose weight than diet and exercise alone. They can also provide other benefits, such as improved cardiovascular health in high-risk groups.

From the very beginning, however, doctors have cautioned that obesity is a chronic condition, one that usually requires constant vigilance to manage. Stopping the habits that led to weight loss can often result in regaining it—even with GLP-1s.

Many studies have shown that people who successfully lose weight typically regain it over time. But the authors wanted to explore how weight regain might differ between people on obesity medication compared to those solely engaged in behavioral weight management programs, such as Weight Watchers. They analyzed data from 37 studies that collectively involved nearly 10,000 participants.

On average, people who stopped taking obesity medication saw their weight return at about 0.9 pounds a month, the researchers found. At that rate, they estimated that people would reach their original baseline weight within one and a half to two years. The verdict was even starker for those specifically on the newest GLP-1 drugs; they saw an average weight regain of 1.8 pounds a month. At that pace, these users would return to their original weight within 1.5 years.

Notably, the rate of weight regain following medication use was more accelerated than the rate observed in people who stopped weight loss programs, which was around 0.7 pounds per month. Participants’ cardiometabolic health markers, such as blood pressure, also began to revert back to baseline and would be expected to regress fully within 1.4 years.

“These medicines are transforming obesity treatment and can achieve important weight loss. However, our analysis shows that people tend to regain weight rapidly after stopping—faster than we see with behavioural programs,” said lead author Sam West, a postdoctoral researcher at Oxford’s Nuffield Department of Primary Care Health Sciences, in a statement from the university.

What to do

To reiterate, the phenomenon of weight regain is nothing new. And there will undoubtedly be some people who can maintain their weight loss once they stop taking a GLP-1, just as a few people have managed to lose weight and keep it off before these drugs were widely available.

But the findings do indicate that many people who want to maintain their weight loss may have to stay on these medications long-term—possibly even for life. Unfortunately, that’s been easier said than done in the real world. Studies have shown that roughly 50% of people on a GLP-1 discontinue use within a year for a variety of reasons, including the high cost of the drug or being unable to tolerate the common gastrointestinal side effects.

More needs to be done for people who are unable or unwilling to stay on these drugs long-term, the researchers say.

“This isn’t a failing of the medicines—it reflects the nature of obesity as a chronic, relapsing condition,” said West.