New research presented at the European Congress on Obesity (ECO 2026) suggests that losing significant weight while taking popular GLP-1 drugs such as Ozempic, Wigoby, Saxenda, and Munjaro may significantly reduce the risk of several obesity-related health problems. The study results also showed that people who gained weight after starting treatment generally had worse health outcomes.
The study was led by Professor John Wilding and colleagues at the University of Liverpool, UK.
Significant weight loss leads to improved health
GLP-1-based drugs such as semaglutide (Ozempic, Wegovy), liraglutide (Saxenda), and tirzepatide (Mounjaro) are widely used to treat obesity and type 2 diabetes. Clinical trials have already shown that these drugs can help people lose weight and improve their overall health. But the researchers wanted to better understand what happens in a real-world setting, where many patients stop taking their medications and weight changes vary widely.
To investigate this, the team analyzed data from Optum Market Clarity, a large electronic medical records and insurance claims database in the United States. Researchers examined patients who started GLP-1-based therapy from January 2021 to June 2024.
The study tracked changes in body mass index (BMI) during the first year after starting treatment. The researchers then examined how these weight changes were associated with subsequent risk of osteoarthritis, chronic kidney disease (CKD), obstructive sleep apnea (OSA), and heart failure through June 2025.
Patients who had already developed any of these conditions before follow-up weight measurements were excluded from the analysis.
Includes approximately 90,000 patients
Overall, 89,718 patients participated in the study. Of these, 75.6% started semaglutide drugs such as Ozempic or Wegovy, 17.5% started tirzepatide (Mounjaro) and 6.9% started liraglutide (Saxenda).
The average patient age at the start of treatment was 57.5 years, and the average BMI was 34.7 kg/m2. Approximately 61% had type 2 diabetes.
Researchers also found that discontinuing treatment was common. Approximately half of all patients discontinued GLP-1 drugs within 1 year, defined as at least 60 days of no treatment.
Nevertheless, the study evaluated all patients based on how much weight they gained or lost during the first year, regardless of whether they continued the medication or not.
Weight loss reduces risk of major diseases
During the first year of treatment, 27% of patients decreased their BMI by less than 5%, and 22.4% decreased their BMI by 5% to 10%. An additional 14.1% achieved a BMI reduction of 10% to 15%, and 15.8% achieved a BMI reduction of at least 15%. On the other hand, 20.8% actually gained weight.
The researchers then followed the patients for an average of 11 more months. During this period, the incidence per 1,000 person-years was 21.4 for osteoarthritis, 21.1 for chronic kidney disease, 20.3 for obstructive sleep apnea, and 3.9 for heart failure.
Compared to patients whose BMI decreased by less than 5%, people whose BMI decreased by at least 15% had a much lower risk of several diseases. The risk of osteoarthritis was 37% lower, the risk of chronic kidney disease was 30% lower, the risk of obstructive sleep apnea was 69% lower, and the risk of heart failure was 32% lower. All findings were statistically significant except for the decrease associated with heart failure.
Weight gain was associated with worse outcomes
The study also found an alarming trend among patients whose BMI increased after starting treatment.
Compared to those whose BMI decreased by less than 5%, those who gained weight had a 10% higher risk of osteoarthritis, a 14% higher risk of chronic kidney disease, a 22% higher risk of obstructive sleep apnea, and a 69% higher risk of heart failure. The increased risk of sleep apnea and heart failure was statistically significant.
The researchers concluded, “In this real-world study, in which half of the patients discontinued GLP-1-based therapy within 1 year of initiation, failure to lose weight was associated with worse clinical outcome, and greater weight loss was associated with decreased risk. These findings highlight the potential clinical importance of achieving and maintaining weight loss after initiation of GLP-1-based therapy.”
