Four vials of Mounjaro injectable medicationShare on Pinterest
Mounjaro is one of the weight loss medications that contain the ingredient trizepatide. MK Photo/Alamy Stock Photo
  • Researchers report that medications that contain the ingredient trizepatide work to help people lose weight, no matter how long they have had weight problems.
  • They say people should remain on these medications long-term for effective weight management because when they go off the drugs, their weight can return.
  • They add that the results of the study show that it is never too late for people to try to lose weight.

Weight loss drugs that contain the ingredient trizepatide such as Mounjaro and Zepbound can help people lose weight and reduce their waist circumference, no matter how long they have had obesity or weight issues.

That’s according to research that will be presented at this year’s European Congress on Obesity in Venice, Italy, in May.

The findings have not been published yet in a peer-reviewed journal.

The U.S. Food and Drug Administration (FDA) has approved both medications — Mounjaro in 2022 for the treatment of type 2 diabetes and Zepbound in 2023 for weight management in adults with a body mass index (BMI) over 30 or a BMI over 27 with at least one weight-related comorbidity.

Researchers used data from several studies using the SURMOUNT phase 3 trials.

In them, they compared tirzepatide medications to a group given a placebo against three other groups of people:

  • Participants with obesity and at least one weight-related comorbidity that was not type 2 diabetes.
  • Individuals with obesity and type 2 diabetes.
  • People without type 2 diabetes after they had undergone a 12-week intensive lifestyle intervention or 36 weeks of tirzepatide.

Participants were also grouped based on the length of time they reported they had weight issues or obesity:

  • 10 years or less
  • Between 10 and 20 years
  • More than 20 years

The scientists evaluated the percentage of change in body weight and waist circumference when participants achieved weight loss targets of 5%, 10%, 15%, 20%, and 25% of total body weight.

The findings included:

  • Participants with weight/obesity issues for less than 10 years who took 10 mg of tirzepatide lost 21% of their body weight after 72 weeks compared to 20% for those with overweight/obesity for between 10 and 20 years and 23% for those with a disease duration of more than 20 years.
  • In the trial, participants with type 2 diabetes who took 15 mg of tirzepatide who had weight/obesity issues for less than 10 years lost 13% of their body weight compared to 16% of those with a disease duration of 10 to 20 years and 17% for more than 20 years.
  • Reductions in waist circumference followed similar trends.

In a press release, the authors concluded:

“Tirzepatide consistently reduced body weight and waist circumference in people living with obesity or overweight with weight-related comorbidities regardless of the duration of disease. These results are consistent with the overall findings from each study.”

“The results are not surprising,” said Dr. Mir Ali, a bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in California who was not involved in the study. “These medications are designed to work with your hormones to help you lose weight. They worked like they were designed to during the study.”

“It is good to offer patients a non-surgical option, but there are some downsides to tirzepatide. For the medication to work, people must remain on it long-term,” Ali told Medical News Today. “When they stop taking it, the weight can return, unless they have taken the time while on the medication to look at and change their dietary and lifestyle habits.”

A study in 2023 reported that people who were switched to a placebo after 36 weeks of medication gained 14% of their weight back. Those who remained on the medication lost an additional 5% of body weight.

“Additionally, the medication is often not covered by insurance,” Ali noted. “There are some side effects, but these are mild – nausea, vomiting, and constipation. We start people on a low dose and work up to decrease side effects.”

Dr. Holly Lofton, the director of NYU Langone Health’s medical weight management program in New York who was not involved in the study, also shared her thoughts.

“The figures demonstrate similar degrees of weight loss, independent of the duration for which the patient has had obesity. The second abstract demonstrates similar weight loss of 5, 10, 15, 20, and 25 percent of initial baseline weight, regardless of their initial BMI,” Lofton told Medical News Today. “For the prescriber, I believe that this information can guide us to determine that it’s never too late to treat a patient with obesity and that we have scientific evidence to sensibly extrapolate the categorical weight loss that is demonstrated in the trials to our patients regardless of their initial BMI or how long they’ve had obesity. That being said, every patient is an individual and it’s important that we use our clinical judgment to determine what the best treatment plan is for the patient.”

Eli Lilly and Company, the manufacturers of Mounjaro and Zepbound, funded this new research as well as the 2023 study.

“Whenever a study is funded by the manufacturer, there is a possibility of biases,” Ali said. “However, a number of other studies have come to the same conclusion, so I think the results can be trusted.”

“Because this subset analysis of a double-blind, placebo-controlled trial, I do not believe that funding by Lilly has influenced these outcomes as these studies are reviewed by the FDA,” Lofton said. “[These were done by] medical peers who do not have a relationship with the company and the studies are also subject to review by data safety monitoring boards.”