New research shows that people who take the weight-loss drug tirzepatide can keep most of the weight off for at least three years.
The findings come from a long-term follow-up of the SURMOUNT-1 trial, which studied people living with obesity or overweight and prediabetes.
The study will be presented at the European Congress on Obesity 2025 in Malaga, Spain.
The study, led by Professor Louis Aronne from Weill Cornell Medicine in New York and researchers from Eli Lilly and Company, followed participants who were consistently taking tirzepatide for three years.
All of them had lost at least 5% of their starting weight during the treatment.
Tirzepatide is a once-weekly injection that was shown in the original SURMOUNT-1 trial to cause significant weight loss over 72 weeks.
This new analysis looked at 690 people who continued the treatment for a full 176 weeks—about 3 years—and stuck with at least 75% of the scheduled doses.
The average age of participants was 49, and most were women. Their average weight was 107 kg, and their average BMI was 38.6, meaning they were living with obesity.
The researchers looked at how much weight people regained after reaching their lowest weight point, also called their nadir weight.
On average, participants hit their lowest weight after about 22 months. By that point, they had lost about 23.1% of their body weight.
Over the next year or so, they gained back an average of only 3.7%, meaning that after three years, they were still down by 19.4% from where they started.
The study also looked at how many people regained different amounts of weight. About 70% of participants regained less than 5% of the weight they had lost.
Fewer than 10% gained back more than 10%. These numbers were similar across the three different doses of tirzepatide—5 mg, 10 mg, and 15 mg.
So far, the research team hasn’t looked at whether there were differences in results based on gender or age, but future studies may explore that.
Professor Aronne said that these results show tirzepatide can help people maintain weight loss over time. Most participants experienced a steady weight loss journey without gaining much of the weight back. This is encouraging news for people using tirzepatide as part of their long-term weight management plan.
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