Weight loss surgery, such as a gastric sleeve or gastric bypass, can be life-changing. For many people, it leads to major weight loss and improvements in health.
But it does not work the same for everyone.
Some people lose less weight than expected after surgery. Others lose weight at first, but then start to regain weight. This can feel frustrating, upsetting and unfair. It is important to say clearly: this is not a failure of willpower. Obesity is a long-term medical condition, and body weight is controlled by powerful biology, including hunger hormones, appetite signals, genes, sleep, stress, medications and the environment around us.
A new study called the BARI-STEP trial gives some encouraging news.
The BARI-STEP trial studied adults who had previously had weight loss surgery but had not lost as much weight as expected. Everyone in the study had either a gastric sleeve or gastric bypass at least one year earlier.
The researchers tested whether semaglutide 2.4 mg once weekly could help. Semaglutide is a medication that acts like a natural gut hormone called GLP-1. It helps reduce appetite, improve fullness and support weight loss.
People in the study were split into two groups:
One group received semaglutide injections once a week.
The other group received a placebo injection, which looked the same but did not contain the active medicine.
Both groups also received lifestyle support, including advice about food and physical activity.
The results were striking.
After 68 weeks, people taking semaglutide lost, on average, about 18% of their body weight.
People taking placebo did not lose weight overall. In fact, they had a very small average weight gain.
To put this into everyday language: for someone weighing 120 kg, an 18% weight loss would be around 22 kg. That is a very meaningful amount of weight loss.
Many people in the semaglutide group achieved large weight reductions:
More than 8 out of 10 lost at least 10% of their body weight.
Around 6 out of 10 lost at least 15%.
Nearly half lost at least 20%.
The study also showed improvements in blood sugar, cholesterol, triglycerides and quality of life. People reported better physical function, self-esteem and ability to manage daily life.
The side effects were similar to what we already know about semaglutide.
The most common side effects were stomach and gut symptoms, especially:
nausea, reduced appetite, diarrhoea, constipation and vomiting.
Most side effects were mild or moderate. There were no new safety concerns specific to people who had previously had bariatric surgery.
However, this medication still needs proper medical supervision. It is not suitable for everyone. People with a history of pancreatitis, certain thyroid cancers, severe gut symptoms, pregnancy, or complex eating disorders may need different advice.
The study also reported one case of a new restrictive eating disorder in the semaglutide group. This is an important reminder that people using weight loss medication should be supported as whole people, not just monitored by the number on the scales.
For years, people who had poor weight loss or weight regain after bariatric surgery had limited options. Some were offered more surgery, but revisional surgery can be complex and is not suitable for everyone.
This study suggests that semaglutide may offer another option: a medicine-based approach that can be used alongside nutrition, movement, psychological support and long-term follow-up.
This is important because obesity is not a short-term problem. It is a chronic condition, which means many people need long-term treatment and support.
If you have had weight loss surgery and feel disappointed by your weight loss, you are not alone.
It does not mean you have failed.
It does not mean the surgery was pointless.
It may mean your body needs further support.
The BARI-STEP trial suggests that semaglutide could be a helpful treatment for some people after bariatric surgery, especially where weight loss has been less than expected or weight has started to return.
The best next step is to speak to a specialist weight management or bariatric team. They can review possible reasons for weight regain or poor weight loss, including eating patterns, medications, sleep, mental health, hormones, surgical factors and medical conditions. They can also advise whether medications such as semaglutide are appropriate and safe for you.
This study is another sign that obesity care is changing.
The future is unlikely to be “surgery or medication”. For many people, it may be surgery and medication, alongside long-term lifestyle, nutritional and psychological support.
That is a more realistic way to treat obesity: not as a short-term diet problem, but as a long-term medical condition that deserves proper care.