Popular weight loss medications such as Ozempic, Wegovy, Saxenda, and Mounjaro have changed the way doctors treat obesity and type 2 diabetes.
Millions of people around the world are now using these medications to help reduce appetite, lose weight, and improve blood sugar control.
Now, a large new study presented at the European Congress on Obesity (ECO 2026) suggests that the amount of weight people lose while taking these medications may strongly affect their future health.
Researchers found that people who lost the most weight had much lower risks of several obesity-related conditions, including sleep apnea, chronic kidney disease, osteoarthritis, and heart failure. In contrast, people who gained weight after starting treatment often faced worse health outcomes.
The study was led by Professor John Wilding from the University of Liverpool in the UK.
GLP-1 medications work by copying natural hormones in the body that help regulate hunger and digestion. These medicines slow stomach emptying, help people feel fuller for longer, and reduce appetite. Some of the drugs also improve blood sugar control, which is especially important for people with type 2 diabetes.
Clinical trials have already shown that these medications can lead to substantial weight loss. However, researchers wanted to understand what happens in ordinary healthcare settings, where patients may stop treatment, regain weight, or experience varying levels of success.
To investigate this, scientists used information from Optum Market Clarity, a large healthcare database in the United States containing electronic medical records and insurance claims.
The researchers analyzed patients who started GLP-1 based medications between January 2021 and June 2024.
The study included nearly 90,000 people. Most participants started semaglutide medications such as Ozempic or Wegovy. Others used tirzepatide, sold as Mounjaro, or liraglutide, known as Saxenda.
At the beginning of treatment, the average patient was 57.5 years old and had an average BMI of 34.7, which falls within the obesity range. Around 61% of participants had type 2 diabetes.
The scientists measured how much each patient’s BMI changed during the first year after starting treatment. BMI, or body mass index, is a common measure used to estimate body fat based on a person’s height and weight.
After tracking weight changes, the researchers studied how those changes affected the later development of several serious conditions linked to obesity.
These included osteoarthritis, which damages joints and causes pain; chronic kidney disease, which affects kidney function; obstructive sleep apnea, a condition where breathing repeatedly stops during sleep; and heart failure, where the heart struggles to pump blood properly.
One striking finding was how common treatment discontinuation became. About half of all patients stopped taking their GLP-1 medication for at least 60 days during the first year.
Despite this, researchers still compared outcomes based on whether people lost weight or gained weight during treatment.
The results showed a clear pattern. Greater weight loss was strongly linked to better health outcomes.
About 15.8% of patients reduced their BMI by at least 15%. Compared with people who lost less than 5% of their BMI, these patients experienced significantly lower risks of several conditions.
Their risk of osteoarthritis was 37% lower. Chronic kidney disease risk dropped by 30%. The risk of obstructive sleep apnea fell dramatically by 69%. Heart failure risk was also lower by 32%, although researchers noted this result was not fully statistically significant.
The study also found worrying results among people who gained weight.
Compared with participants 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 sleep apnea, and a 69% higher risk of heart failure.
The increases in sleep apnea and heart failure risk were especially significant.
Researchers say the findings highlight how closely obesity is connected to many chronic diseases. Excess body fat places additional pressure on joints, affects breathing, increases inflammation, strains the heart, and contributes to metabolic problems that damage organs over time.
Losing weight may therefore improve health across many different systems in the body, not just appearance or blood sugar levels.
The study also demonstrates one of the major challenges of obesity treatment. Although GLP-1 medications can be highly effective, many patients struggle to continue taking them long term.
Some people stop treatment because of nausea, stomach side effects, cost, insurance coverage problems, or difficulty maintaining lifestyle changes.
Scientists are continuing to study whether patients can maintain weight loss after stopping the medications and whether long-term use may provide even greater health protection.
Researchers caution that the study does not prove the medications directly caused the reduced disease risks. Instead, it shows that greater weight loss after treatment was associated with better outcomes.
The findings may encourage doctors to focus more strongly on helping patients achieve sustained weight loss rather than only starting medication.
If you care about weight loss, please read studies that hop extract could reduce belly fat in overweight people, and early time-restricted eating could help lose weight .
For more health information, please see recent studies that Mediterranean diet can reduce belly fat much better, and Keto diet could help control body weight and blood sugar in diabetes.
Source: University of Liverpool.
