Overweight people lose 27kg on diabetes drug with diet and exercise: study

The medicine in the diabetes drug Mounjaro helped people who had obesity or who were overweight lose at least a quarter of their body weight, or about 27kg (60 pounds) on average, when combined with intensive diet and exercise, a new study shows.

By comparison, a group of people who also dieted and exercised, but then received dummy shots, lost weight initially but then regained some, researchers reported in the journal Nature Medicine.

“This study says that if you lose weight before you start the drug, you can then add a lot more weight loss after,” said Dr Thomas Wadden, an obesity researcher and psychology professor at the University of Pennsylvania, in the US, who led the study.

The results, which were also presented at a medical conference, confirm that the drug made by Eli Lilly has the potential to be one of the most powerful medical treatments for obesity to date, outside experts said.

“Any way you slice it, it’s a quarter of your total body weight,” said Dr Caroline Apovian, who treats obesity at Brigham and Women’s Hospital in the US state of Massachusetts, who wasn’t involved in the study.

The injected drug, tirzepatide, was approved in the United States in May 2022 to treat diabetes. Sold as Mounjaro, it has been used “off-label” to treat obesity, joining a frenzy of demand for diabetes and weight-loss medications including Ozempic and Wegovy, made by Novo Nordisk.

All the drugs, which carry retail price tags of US$900 a month or more, have been in shortage for months.

Tirzepatide targets two hormones that kick in after people eat to regulate appetite and the feeling of fullness communicated between the gut and the brain. Semaglutide, the drug used in Ozempic and Wegovy, targets one of those hormones.

The new study, which was funded by Eli Lilly, enrolled about 800 people who had obesity or were overweight with a weight-related health complication – but not diabetes. On average, study participants weighed about 109.5kg to start and had a body-mass index – a common measure of obesity – of about 38.

After three months of intensive diet and exercise, more than 200 participants left the trial, either because they failed to lose enough weight or for other reasons.

The remaining nearly 600 people were randomised to receive tirzepatide or a placebo via weekly injections for about 16 months. Nearly 500 people completed the study.

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Participants in both groups lost about 7 per cent of their body weight, or almost 8kg, during the diet-and-exercise phase. Those who received the drug went on to lose an additional 18.4 per cent of initial body weight, or about 20kg more, on average.

Those who received the dummy shots regained about 2.5 per cent of their initial weight, or 2.7kg.

Overall, about 88 per cent of those taking tirzepatide lost 5 per cent or more of their body weight during the trial, compared with almost 17 per cent of those taking the placebo. Nearly 29 per cent of those taking the drug lost at least a quarter of their body weight, compared with just over 1 per cent of those taking the placebo.

That’s higher than the results for semaglutide and similar to the results seen with bariatric surgery, Apovian said.

“We’re doing a medical gastric bypass,” she said.

She went from 130kg to 76kg after gastric sleeve surgery

Side effects including nausea, diarrhoea and constipation were reported more frequently in people taking the drug than those taking the placebo. They were mostly mild to moderate and occurred primarily as the dose of the drug was escalated, the study found.

More than 10 per cent of those taking the drug discontinued the study because of side effects, compared with about 2 per cent of those on placebo.

Eli Lilly is expected to publish the results soon of another study that the firm says shows similar high rates of weight loss.

The US Food and Drug Administration has granted the company a fast-track review of the drug to treat obesity, which Eli Lilly may sell under a different brand name. A decision is expected by the end of the year.