- People who had bariatric surgery lost around five times more weight than those using GLP-1 injections over two years
- Real-world weight loss from GLP-1 drugs was far lower than results reported in clinical trials, partly due to high dropout rates
- The findings highlight surgery as the most effective and durable option for severe obesity, while medications still help some people
Injectable weight loss drugs such as semaglutide and tirzepatide have attracted huge attention, but new real-world data suggest they deliver far less weight loss than surgery outside clinical trials.
A large comparison study found that people who underwent bariatric surgery lost dramatically more weight over two years than those treated with GLP-1 medications.
Researchers analysed electronic health records from more than 51,000 patients treated between 2018 and 2024 across two large US health systems.
All participants had a body mass index of at least 35. Some underwent bariatric surgery, either sleeve gastrectomy or gastric bypass, while others were prescribed injectable GLP-1 drugs such as semaglutide or tirzepatide.
After adjusting for age, starting weight and medical conditions, the differences were stark.
Two years after treatment, people who had surgery lost an average of 58 pounds (24.5 kg), equivalent to around 24% of their body weight.
By comparison, patients prescribed GLP-1 drugs for at least six months lost about 12 pounds on average, or around 4.7% (5.4 kg) of body weight.
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Even among those who remained on GLP-1 treatment continuously for a full year, average weight loss reached only 7%.
This was still far below the results seen with surgery.
The authors point to a key reason for the gap between trials and real life. In controlled trials, patients receive close monitoring and support.
In everyday practice, many people stop GLP-1 treatment due to side effects, cost or difficulty maintaining weekly injections.
Previous research suggests more than half of patients discontinue GLP-1 drugs within one year and over 70% by two years.
By contrast, bariatric surgery produces a large and sustained physiological change that does not depend on ongoing medication adherence.
Despite this, surgery remains underused. Only a small fraction of people who meet eligibility criteria ever receive it.
The researchers stress that this is not an argument against GLP-1 drugs.
Many patients do benefit, particularly in the short term or when surgery is not suitable.
The findings instead highlight the importance of matching people to the right treatment and setting realistic expectations.
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For people living with obesity and type 2 diabetes, the results reinforce what long term data have shown for years.
Bariatric surgery remains the most effective option for substantial and durable weight loss and often leads to major improvements in blood glucose control.
Medications can still play a valuable role, but in the real world they rarely match surgical outcomes on their own.
