New research presented at the European Congress on Obesity (ECO 2026) suggests that greater weight loss while taking popular GLP-1 medications such as Ozempic, Wegovy, Saxenda, and Mounjaro may significantly reduce the risk of several obesity-related health problems. The findings also showed that people who gained weight after starting treatment generally faced worse health outcomes.
The study was led by Professor John Wilding from the University of Liverpool in the UK along with fellow researchers.
Greater Weight Loss Linked to Better Health
GLP-1 based medications, including 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 overall health. However, researchers wanted to better understand what happens in real-world settings, where many patients stop taking the medications and weight changes vary considerably.
To explore this, the team analyzed data from Optum Market Clarity, a large US electronic health record and insurance claims database. The researchers examined patients who started GLP-1 based treatments between January 2021 and June 2024.
The study tracked changes in body mass index (BMI) during the first year after treatment began. Researchers then looked at how those weight changes related to later risks of osteoarthritis, chronic kidney disease (CKD), obstructive sleep apnea (OSA), and heart failure through June 2025.
Patients who had already developed one of those conditions before their follow-up weight measurements were excluded from the analysis.
Nearly 90,000 Patients Included
The study involved 89,718 patients overall. Among them, 75.6% started semaglutide medications such as Ozempic or Wegovy, 17.5% started tirzepatide (Mounjaro), and 6.9% began liraglutide (Saxenda).
At the beginning of treatment, the average patient was 57.5 years old with an average BMI of 34.7 kg/m2. About 61% had type 2 diabetes.
Researchers also found that stopping treatment was common. Roughly half of all patients discontinued their GLP-1 medication within one year, defined as going at least 60 days without treatment.
Despite that, the study evaluated all patients according to how much weight they lost or gained during the first year, regardless of whether they stayed on the medication.
Weight Loss Reduced Risk of Major Conditions
During the first year after starting treatment, 27% of patients lowered their BMI by less than 5%, while 22.4% reduced it by between 5% and 10%. Another 14.1% achieved a reduction between 10% and 15%, and 15.8% lowered their BMI by at least 15%. Meanwhile, 20.8% actually gained weight.
Researchers then followed patients for an average of 11 additional months. During that time, the incidence rates per 1,000 person-years were 21.4 for osteoarthritis, 21.1 for chronic kidney disease, 20.3 for obstructive sleep apnea, and 3.9 for heart failure.
Compared with patients who lost less than 5% of their BMI, people who reduced their BMI by at least 15% experienced much lower risks for several conditions. Their risk of osteoarthritis was 37% lower, chronic kidney disease was 30% lower, obstructive sleep apnea was 69% lower, and heart failure was 32% lower. All of the findings were statistically significant except the reduction linked to heart failure.
Weight Gain Was Tied to Worse Outcomes
The study also found troubling trends among patients whose BMI increased after starting treatment.
Compared with people who lost less than 5% of their BMI, 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 increases in sleep apnea and heart failure risk were statistically significant.
The researchers concluded: “In this real-world study where half of patients discontinued GLP-1-based treatment within a year after initiation, not losing weight was associated with worse clinical outcomes while larger reductions were associated with decreased risks. These findings highlight the potential clinical importance of achieving and maintaining weight loss after GLP-1-based treatment initiation.”