Weight rebound after obesity drugs shows need for long-term treatment, researchers say

People who stop taking weight-loss drugs regain body mass four times faster than those who lost their excess pounds through diet and exercise, according to an analysis of the latest studies.

The additional benefits from taking weight-loss drugs, such as improvements in cholesterol and blood pressure, were also reversed when patients quit the medications, the study found.

The research, published in the British Medical Journal on Thursday, adds to a growing body of evidence that suggests life-long treatment of obesity is needed to maintain control of the condition. But the high cost of the latest drugs — as well as their side effects — present barriers to long-term use.

“We know that obesity is a chronic relapsing condition. We know that when treatment stops, weight is regained. And so, some kind of treatment needs to be continued. What [that] treatment should be, I don’t know,” co-author Susan Jebb, professor of diet and population health at the Nuffield Department of Primary Care Health Sciences, University of Oxford, told journalists.

Rates of obesity and overweight are growing rapidly on the continent, with around 51 percent of people in the EU aged 16 years or over being overweight in 2022. Obesity significantly increases the risk of chronic illnesses such as diabetes, heart disease and cancers, and health systems are struggling to cope.

Researchers analyzed weight gain from 37 trials of multiple weight-loss drugs, including older medications and the newer GLP-1s. The latest drugs, including Novo Nordisk’s diabetes and weight-loss drugs Ozempic and Wegovy and Eli Lilly’s Mounjaro, saw the greatest weight loss and the fastest weight regain when treatment stopped.

Compared with another analysis of behavioral weight management programs supporting low energy diets and exercise, weight regain was faster after ending medication than after ending behavioral programs.

The long-term dilemma

The newer weight-loss drugs have seen a boom in uptake across Europe and America, despite their high prices. Ozempic, Wegovy and Mounjaro soared in popularity after demonstrating roughly 15 percent weight loss in trials, and were pounced on by celebrities and influencers.

However, around half of people who take these drugs will stop them after one year. Side effects such as nausea and vomiting, costs or dissatisfaction with weight loss as it plateaus are driving decisions to halt treatment, lead author Sam West, a postdoctoral researcher also at the Nuffield department at the University of Oxford, told journalists during the briefing.

Most people in the U.K. — around 90 percent — pay privately for their weight-loss medication, Jebb said. But those who access it through the National Health Service are subject to a two-year cap on access to the drugs, known as GLP-1s. Similar limits apply in other EU countries.

Dimitris Koutoukidis, associate professor in diet, obesity and behavioral sciences at the University of Oxford, suggested the U.K. may not be getting the value for money it envisioned with these weight-loss drugs.

The model used to assess whether Lilly and Novo’s medicines were cost-effective assumed people would regain their lost weight after two years, he told journalists — but their study shows weight is regained at around 1.5 years.

“It is really hard to treat obesity and keep the weight off long-term,” Jebb said.

“That should make us put even more effort into preventing weight gain in the first place. And if we could transform our food environment to make it easier for people to manage their weight it would stop them gaining weight in the first place and help people — after a successful weight loss attempt — to keep it off.”

“These treatments are not a whole solution,” she added.