We’ve got fresh evidence for how weight can quickly be regained after weight-loss programs stop – but rather than looking at traditional dieting, here the researchers wanted to focus on anti-obesity medications (AOMs), as they continue to be used ever more widely.
A team from Peking University in China reviewed 11 previous studies involving a total of 2,466 people. The studies covered a variety of AOMs, including those known as glucagon-like peptide-1 receptor agonists (GLP-1 drugs, such as Ozempic and Wegovy), which impersonate the natural hormone GLP-1 to control appetite and blood sugar.
Overall, the researchers found that AOMs were effective at helping people to lose weight. However, they all had something else in common: the weight tended to come back once the course of drugs was over.
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“Significant weight regain occurred eight weeks after discontinuation of AOMs and was sustained through 20 weeks,” explains the research team, led by first author Han Wu. “Different weight regain was observed in subjects with different characteristics.”
Of the different types of weight loss treatments covered, it was those in the GLP-1 category that showed the most weight gain after treatment had stopped, driving the rest of the results – though they did account for most of the studies analyzed.
Some 20 weeks after stopping their drugs, the participants in the studies had put back on an average of 2.5 kilograms (5.5 pounds). The team also found that people who lost more weight tended to regain more afterwards too.
To help isolate the effects of stopping the medicines, the researchers accounted for several other factors that can also influence weight loss, including levels of exercise and whether or not the individuals concerned had diabetes.
Why this is happening isn’t clear. Future studies might be able to look at the underlying reasons more closely, but there’s the possibility that weight loss somehow rewires the body in a variety of ways that then make it harder to keep to a healthy weight.
“The effects of weight cycling on health and systemic metabolism are not thoroughly defined,” write the researchers.
One of the previous studies looked at in the new analysis was published in 2023, and found that when weekly injections of tirzepatide (or Zepbound) were stopped and participants were switched to a placebo, an average of half the lost weight came back again.
It’s worth pointing out that this isn’t just a problem with weight-loss drugs. It’s something that’s also been seen in other approaches to staying slim, including gastric bypasses and vertical banded gastroplasty.
However, it’s another consideration to bear in mind when weighing up AOMs that produce impressive results – there may be a cost to pay later. Questions have already been asked about some of the side effects and health risks that may come with AOMs.
For now, the researchers are keen to see new studies carried out, covering bigger sample groups over longer periods of time. It’s possible that we can find better ways of supporting people once they come off AOMs – or find healthier alternatives to them.
“Studies with longer follow-up duration are required to further investigate the potential factors associated with weight change after discontinuation of treatment,” write the researchers.
The research has been published in BMC Medicine.
