Doctor Warns About Stopping GLP-1 Weight Loss Drugs and Explains How Fast the Body Can Rebound

Dr. Amir Khan has cautioned that people who stop GLP-1 weight loss medicines could regain most or all of the weight they lost within two years unless they have the right nutritional support in place.

The British TV doctor, a regular on ITV’s This Morning and Good Morning Britain, discussed the issue on his podcast No Appointment Necessary with co-host Cherry Healy. Khan, whose medical advice reaches millions through television and social media, responded to a listener’s question about whether weight loss lasts after the drugs are discontinued.

“Yes is the answer, if they haven’t done all the wraparound care in terms of getting their nutrition right,” Dr. Amir said.

Healy then asked whether the “food noise” that GLP-1s suppress comes back in patients who have genuinely improved their diets during treatment. Khan said it does, and that it returns quickly.

“What the studies show, and there have been studies on this, within four weeks your body reverts back in terms of the voices in your head, the hormones that have been changed by these drugs all revert back to what they were within four weeks,” Dr. Amir explained.

He said the rebound continues over time, citing research that found patients regain about 60 percent of the weight they had lost within a year, with many returning to their pre-treatment weight by two years.

Khan stressed that this is not simply a matter of discipline. He said the body’s hormonal systems shift rapidly after the medication is stopped, restoring the neurological and endocrine patterns that previously encouraged overeating.

The discussion also covered what patients lose while taking GLP-1s, and Khan noted that the loss is not limited to fat. He drew a distinction between adipose tissue and lean mass, explaining that muscle is only one part of the latter.

“When we talk about lean weight, we’re not just talking about muscle. That is one part of that. And actually, there is quite a significant loss in your lean weight loss as well as as alongside the fat,” Dr. Amir said.

He referred to one study showing participants lost between 20 and 40 percent of their lean weight during treatment. He said that kind of weight loss can affect metabolism, physical performance, and the body’s response during and after medication use.

Khan also explained why some people stop losing weight even when they keep taking the drugs as prescribed. In his view, the body reacts to a prolonged calorie deficit by trying to protect itself.

“All it knows is that you are taking in less calories and that puts it into starvation mode,” he said.

“So, it will fight back. It will try and switch on your hunger hormones again. It will slow down your metabolism. So, you’re not losing weight that rapidly. It will hold on to your fat and your storage much more aggressively than it would have done before.”

He said those same defenses — stronger hunger signals, a slower metabolism and greater fat retention — are part of what returns within weeks of stopping the medication.

On how long patients can stay on GLP-1s, Khan drew a distinction between two groups. People using the drugs for type 2 diabetes may continue them long term as part of chronic disease management.

“If you’re on it for type two diabetes, you can be on it for as long as you need to be on them, which can be forever because it’s managing your long-term chronic condition,” he said.

The podcast came amid growing worldwide demand for GLP-1 receptor agonists such as semaglutide, sold as Wegovy and Ozempic, and tirzepatide, sold as Mounjaro. The drugs have reshaped obesity treatment while also raising lasting questions about dependence and what happens after treatment ends.

Khan’s warning highlights a gap in public understanding: while the medicines suppress appetite, lasting results depend on behavioral and nutritional changes that continue after the prescription stops.