UNITED STATES (AP) – As a growing number of overweight Americans clamour for Ozempic and Wegovy — drugs touted by celebrities and on TikTok to pare pounds — an even more powerful obesity medicine is poised to upend treatment.

Tirzepatide, an Eli Lilly and Co drug approved to treat type 2 diabetes under the brand name Mounjaro, helped people with the disease who were overweight or had obesity lose up to 16 per cent of their body weight, or more than 34 pounds, over nearly 17 months, the company said on Thursday.

The late-stage study of the drug for weight loss adds to earlier evidence that similar participants without diabetes lost up to 22 per cent of their body weight over that period with weekly injections of the drug. For a typical patient on the highest dose, that meant shedding more than 50 pounds.

Having diabetes makes it notoriously difficult to lose weight, said Dr Nadia Ahmad, Lilly’s medical director of obesity clinical development, which means the recent results are especially significant. “We have not seen this degree of weight reduction,” she said.

Based on the new results, which have not yet been published in full, company officials said they will finalise an application to the US Food and Drug Administration for fast-track approval to sell tirzepatide for chronic weight management. A decision could come later this year. A company spokeswoman would not confirm whether the drug would be marketed for weight loss in the US under a different brand name.

If approved for weight loss, tirzepatide could become the most effective drug to date in an arsenal of medications that are transforming the treatment of obesity, which affects more than 4 in 10 American adults and is linked to dozens of diseases that can lead to disability or death.

“If everybody who had obesity in this country lost 20 per cent of their body weight, we would be taking patients off all of these medications for reflux, for diabetes, for hypertension,” said Dr. Caroline Apovian, a director of the Center for Weight Management and Wellness at Brigham and Women’s Hospital. “We would not be sending patients for stent replacement.”

Industry analysts predict that tirzepatide could become one of the top-selling drugs ever, with annual sales topping $50 billion. It is expected to outpace Novo Nordisk’s Ozempic — a diabetes drug used so commonly to shed pounds that comedian Jimmy Kimmel joked about it at the Oscars — and Wegovy, a version of the drug also known as semaglutide approved for weight loss in 2021. Together, those drugs made nearly $10 billion in 2022, with prescriptions continuing to soar, company reports show.

Tirzepatide is the first drug that uses the action of two hormones, GLP-1 and GIP, for greater effects. It also targets the chemical signals sent from the gut to the brain, curbing cravings and thoughts of food.

Though the drugs appear safe, they can cause side effects, some serious. Most common reactions include diarrhea, nausea, vomiting, constipation and stomach pain. Some users have developed pancreatitis or inflammation of the pancreas, others have had gallbladder problems. Mounjaro’s product description warns that it could cause thyroid tumors, including cancer.