New research presented at the European Congress on Obesity (ECO 2026) suggests that people who lose more weight while taking popular GLP-1 medications may significantly lower their risk of several serious health conditions linked to obesity.
The study also found that people who gained weight after starting these medications often had worse health outcomes.
The research was led by Professor John Wilding from the University of Liverpool in the United Kingdom together with an international research team. The findings help provide a clearer picture of what happens to people using these medications in real-world medical settings, outside of carefully controlled clinical trials.
In recent years, GLP-1 based medications such as Ozempic, Wegovy, Saxenda, and Mounjaro have become widely known for helping people lose weight and manage type 2 diabetes. These drugs work by copying hormones in the body that help control hunger, blood sugar, digestion, and feelings of fullness.
Many people taking these medications eat less because they feel full more quickly and stay satisfied longer after meals. Clinical trials have shown that the medications can lead to major weight loss for some patients. Doctors have also seen improvements in blood sugar levels, blood pressure, and heart health.
However, researchers have been eager to understand whether the same benefits happen in everyday life, where patients often stop taking the medications, struggle to maintain weight loss, or regain weight after treatment.
To explore this question, the researchers analyzed data from Optum Market Clarity, a large United States database containing electronic medical records and insurance claims. The study included patients who started GLP-1 medications between January 2021 and June 2024.
The researchers focused on three major types of GLP-1 related medications. About 75.6% of patients started semaglutide drugs such as Ozempic or Wegovy. Another 17.5% started tirzepatide, sold under the brand name Mounjaro, while 6.9% used liraglutide, commonly known as Saxenda.
In total, the study included 89,718 patients. At the beginning of treatment, the average participant was 57.5 years old and had an average body mass index, or BMI, of 34.7 kg/m2. Around 61% of participants also had type 2 diabetes.
BMI is a common measurement used to estimate body fat based on height and weight. A BMI over 30 is generally considered obesity.
The researchers tracked how much each person’s BMI changed during the first year after starting treatment. They then looked at whether those weight changes affected the later risk of several obesity-related health conditions.
The conditions included osteoarthritis, chronic kidney disease, obstructive sleep apnea, and heart failure. Patients who already had one of these conditions before follow-up measurements were excluded from that part of the analysis.
One major finding was that many patients stopped treatment within the first year. Roughly half of all patients discontinued their GLP-1 medication for at least 60 days during the first year after starting treatment.
Despite this, researchers still analyzed all patients according to whether they lost weight, maintained weight, or gained weight during the first year.
The results showed a strong relationship between greater weight loss and lower health risks.
About 27% of patients lowered their BMI by less than 5%. Another 22.4% reduced it by between 5% and 10%. Around 14.1% lowered BMI by between 10% and 15%, while 15.8% achieved reductions of at least 15%.
However, 20.8% of patients actually gained weight after starting treatment.
Researchers followed patients for an additional average of 11 months after the first year. During this period, they measured how often different health conditions developed.
Compared with people who lost less than 5% of their BMI, patients who lowered their BMI by at least 15% had significantly lower risks for several conditions.
Their risk of osteoarthritis was 37% lower. The risk of chronic kidney disease was 30% lower. The risk of obstructive sleep apnea was reduced by an impressive 69%. Heart failure risk was also 32% lower, although researchers noted this particular result did not reach full statistical significance.
At the same time, patients who gained weight generally had worse outcomes.
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 especially strong and statistically significant.
The findings highlight the importance not only of starting treatment but also of achieving and maintaining meaningful weight loss over time.
Researchers say obesity affects many systems throughout the body. Excess body fat can place extra pressure on joints, strain the heart, interfere with breathing during sleep, and damage kidney function. Losing weight may help reduce these stresses and lower the risk of serious complications.
The study also reflects one of the biggest challenges with GLP-1 medications: many patients eventually stop taking them. Some people discontinue treatment because of side effects, cost, insurance problems, or difficulty maintaining long-term use.
Scientists are still studying what happens after people stop the medications and how patients can best maintain weight loss over time.
The researchers emphasized that the study does not prove the medications themselves directly prevented disease. Instead, the findings show that larger weight loss was strongly associated with better health outcomes.
The study findings are important because they provide large real-world evidence that greater weight loss after starting GLP-1 medications may reduce the risk of several obesity-related diseases.
One major strength of the study is its enormous sample size of nearly 90,000 patients, which gives researchers a clearer view of how these medications perform outside clinical trials. The study also highlights the importance of maintaining weight loss rather than simply starting medication.
However, because the research was observational, it cannot fully prove cause and effect. Many factors, including lifestyle habits, medical care, and differences between patients, may also influence the results. More long-term studies will still be needed to understand how lasting weight loss and long-term medication use affect overall health outcomes.
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Source: University of Liverpool.
