For adults struggling with obesity, a weekly injection of tirzepatide offers significant hope. New research presented at the European Congress on Obesity (ECO) in Malaga, Spain, shows that the drug leads to lasting weight loss over a three-year period. This breakthrough could reshape how healthcare providers treat obesity in adults without diabetes, paving the way for more personalized approaches to managing weight.
Sustained Weight Loss Across Various Groups
The study, led by Dr. Luca Busetto from the University of Padova, tracked 700 adults with overweight or obesity but no diabetes. This research extended the SURMOUNT-1 trial and examined the effects of weekly tirzepatide doses—5 mg, 10 mg, or 15 mg—over three years. On average, participants lost between 10% and 30% of their starting weight, with most maintaining their weight loss throughout the study.
“Our analysis confirms that tirzepatide can sustain clinically meaningful weight loss for up to three years,” Dr. Busetto said. He emphasized that significant weight loss was achievable regardless of age, BMI, or the length of time someone had been overweight.
Diverse Weight Loss Responses
Not all participants lost weight in the same way. Researchers identified three distinct patterns of weight loss:
Gradual Weight Loss: Some participants lost around 10% of their weight at a steady pace.
Rapid Initial Loss: Another group lost about 20% of their weight early but then plateaued.
Most Successful Group: The third group experienced the most rapid weight loss, shedding up to 30% of their weight within the first year, before stabilizing.
Women and those without obesity-related health conditions most commonly fell into the third group, achieving the highest levels of weight loss. Dr. Busetto explained that participants in Group 1 had lost about 10% of their weight after three years, while those in Group 3 lost up to 31%.
How Tirzepatide Works
Tirzepatide works by mimicking two hormones—glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP)—which play key roles in regulating insulin after meals. It also slows digestion and sends signals to the brain to reduce hunger, promoting a feeling of fullness. Approved by the U.S. FDA as Zepbound in November 2023 and by European regulators as Mounjaro in June 2024, the medication targets obesity or overweight in adults with health issues such as high blood pressure or cholesterol.
Why Weight Plateaus Occur
Despite its effectiveness, most participants eventually hit a weight plateau, a common part of the weight loss process. Dr. Busetto explained that weight loss plateaus happen because hormones, including GLP-1 and GIP, eventually trigger protective mechanisms to prevent further weight loss. The timing of the plateau varied, with those losing weight rapidly reaching it after 36 to 48 weeks, while others plateaued after about 24 weeks.
Minimal Weight Regain Over Three Years
Another key finding of the study was the minimal weight regain experienced by participants. Over the course of three years, most adults regained only about 4% of their lowest weight. Around 70% of participants regained 5% or less, and fewer than 10% regained more than 10%. Professor Louis Aronne from Weill Cornell Medicine noted that these results were promising because most participants maintained stable weight without significant regain.
Health Benefits Beyond Weight Loss
The benefits of tirzepatide extend beyond weight loss. Dr. Busetto pointed out that even modest weight loss—such as losing 5% of initial body weight—can significantly reduce the risk of developing diabetes. A 15% weight loss can lead to major improvements in blood pressure and cholesterol levels. The study also confirmed that tirzepatide has a strong safety profile, with no new health issues emerging over the three years. The most common side effects were mild gastrointestinal symptoms like nausea, diarrhea, and constipation, consistent with previous trials.
Moving Toward Personalized Obesity Treatments
These promising long-term results suggest that tirzepatide could become a key tool in personalized weight management. By identifying individuals who are most likely to benefit from tirzepatide early, healthcare providers can tailor treatment plans to optimize weight loss outcomes. Dr. Busetto noted that this research could help doctors predict a patient’s weight loss trajectory and set realistic goals based on their health profile.
Ongoing Research and Future Directions
While the current study focused on adults without diabetes, further research is needed to explore how tirzepatide affects other groups, including different age and gender demographics. Studies will also investigate how weight regain may vary across these groups, leading to more specific recommendations in the future.
Overall, these groundbreaking findings confirm that tirzepatide is an effective, long-lasting option for managing obesity and overweight. The study reshapes expectations for weight loss treatment and highlights the potential for sustained, meaningful weight loss in a wide range of adults.
Conflict of Interest:
Professor Louis Aronne reports receiving grants and fees from Eli Lilly and Company and other manufacturers of obesity and diabetes medications. Other co-authors are employees and shareholders of Eli Lilly and Company.
