Tirzepatide, sold under the brand name Mounjaro, has been studied in people without diabetes at three doses: 5, 10 and 15 milligrams. Obese or overweight participants who took the 5 milligram dose lost an average of 35 pounds (16 kilograms), those who took the 10 milligram dose lost an average of 49 pounds (22 kilograms), and those who took the 15 milligram dose lost an average of 49 pounds (22 kilograms). Dose lost an average of 52 pounds (23.6 kilograms).
“Almost 40% of people lost a quarter of their body weight,” said co-author Dr. Ania Jastreboff, co-director of the Yale Center for Weight Management, in a media briefing.
“The data were pretty impressive,” said Dr. Robert Gabbay, Chief Medical Officer of the American Diabetes Association, speaking to CNN from the ADA’s 82nd Scientific Sessions in New Orleans, where the study results were presented.
“The weight loss they achieved in this study was even greater than in previous studies in people with diabetes,” said Gabbay, who was not affiliated with the study.
“The median range of weight loss for people in this new study was 49 pounds — 49 pounds is a lot,” he said. “It’s the realm of weight loss that we usually think is only possible through surgery.”
“It’s not an uncommon observation,” he said. “Previous weight-loss medications are less effective in people with diabetes, and we honestly don’t know exactly why.”
However, the effect of tirzepatide on people with diabetes is still “profound,” Gabbay said, “and offers much more than other agents that we’ve had.”
For the new study, weekly injections of tirzepatide were tested in more than 2,500 people without diabetes with a body mass index (BMI) over 30 or a BMI over 27 and at least one weight-related medical condition, such as high blood pressure, high cholesterol or cardiovascular disease . A measure of a person’s height-to-weight ratio, a BMI of 25 or greater is considered overweight in adults.
At the start of the study, the participants had an average weight of 231 pounds (104.8 kilograms) and an average BMI of 38.
Adults in the study injected themselves with tirzepatide or a placebo once a week using “a small pen-like device with a tiny, tiny needle,” Gabbay said. “The prick from this needle is less painful than, for example, people who prick their fingers to measure their blood sugar.”
Study participants also received counseling sessions to help them maintain a healthy diet with a daily deficit of 500 calories and at least 150 minutes of physical activity per week. While this certainly helped, it doesn’t explain the magnitude of the weight loss seen in the study, Gabbay said.
“The kind of weight loss that we see when people exercise and change their calorie intake is somewhere in the range of 5% to 7%,” he said. “This study showed significantly greater weight loss, far in excess of what we would imagine with lifestyle changes.”
The most commonly reported side effects were nausea, diarrhea and constipation. Between 2.6% and 7.1% of participants discontinued treatment due to side effects.
Mounjaro carries a boxed warning about thyroid tumors and should not be taken by anyone with a family history of certain thyroid disorders.
“Obesity should be treated like any other chronic disease — with effective and safe approaches that target the underlying (causes of) disease… and these results underscore that Tirzepatide may do just that,” said Jastreboff of the Yale Center for Weight Management in a press release from the American Diabetes Association.
“These results are an important step forward in potentially expanding effective therapeutic options for people living with obesity.”