Weight-loss drugs may help people shed kilos, but much of that weight tends to come back soon after treatment stops, according to a major new study published in The BMJ.
The study, published on January 7, 2026, by West, S. et al., suggests that slimming medications work best only while people stay on them — and that stopping them without a longer-term plan can lead to quick weight regain.
What the researchers looked at
The researchers analysed results from 37 studies involving more than 9,300 adults who were overweight or obese. These studies tracked people who used weight management medications for at least eight weeks, then followed them for weeks or months after they stopped taking the drugs.
The team compared what happened after people stopped using slimming drugs with what happened after people stopped non-drug weight-loss programmes, such as diet and lifestyle changes.
How quickly does the weight come back?
On average, people regained about 0.4 kg a month after stopping weight-loss drugs. That means many could put back several kilos within just a few months.
More importantly, the study found that weight came back faster after stopping slimming drugs than after stopping diet-and-exercise programmes. Even when people lost a lot of weight during treatment, it did not stop the kilos from creeping back once the medication ended.
Health benefits also fade over time
The weight regain was not just about appearance or the number on the scale. Improvements in health markers such as blood sugar, cholesterol and other heart-related measures were also found to gradually return to pre-treatment levels.
The researchers estimated that these health benefits could disappear within about 1.4 years after stopping the medication.
What this means for people considering slimming drugs
The study does not say weight-loss drugs are ineffective. Instead, it highlights that they are not a quick fix.
According to the study, using slimming drugs for short periods without a long-term plan may lead to disappointment. This is because weight regain appears to be common and rapid once treatment ends. They suggest these medications should be part of a broader, long-term approach that includes lifestyle changes, rather than being used on their own.
Slimming drugs can help people lose weight, but this large review published in The BMJ shows that most of the lost weight is likely to return within months after stopping treatment. For lasting results, experts say medication alone is unlikely to be enough without ongoing lifestyle support and long-term weight management strategies.
