Dr Amir Khan has issued a fresh warning to anyone thinking of coming off weight-loss injections such as Wegovy or Mounjaro. The NHS GP and TV doctor explained all in a new episode of his podcast, No Appointment Necessary, alongside his co-host Cherry Healy.
What happens when you stop taking them
During the episode, Dr Amir Khan warns that stopping weight-loss injections without significant lifestyle changes often leads to weight returning. He explains that studies show that within four weeks of stopping the medication, the hunger hormones and 'voices in your head' revert to their original state.
"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," he said. He warns that the computer essentially "resets to factory settings" during this timeframe.
He also says that within one year of stopping, research suggests people regain approximately 60% of the weight they lost, and many return to their original starting weight within two years.
Why does weight return after stopping injections?
According to Dr Amir Khan, weight returns after stopping injections because the body's internal hormonal mechanisms revert to their previous state. Specifically, he explains that within four weeks of stopping the medication, the hunger hormones and 'voices in your head' that were suppressed by the drug return to their factory settings.
"All it knows is that you are taking in less calories and that puts it into starvation mode. 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.
He says that because the body perceives the previous rapid weight loss as a state of starvation, it aggressively fights back to restore its original weight by increasing hunger and slowing metabolism.
How long does the NHS recommend treatment?
Generally speaking, the NHS recommends a minimum of two years of treatment with weight-loss injections to allow individuals time to make necessary lifestyle changes. However, Dr Amir Khan notes that this is not a strict rule and that many people may require treatment for a longer period, as obesity is a complex, long-term chronic condition.
"NHS suggests two years at least to make all those changes, but that isn't a hard and fast rule and a lot of people may need to be on it for longer than that. I suspect what we'll find is actually two years isn't enough, and things bounce back as they once were, and they'll be on it long term."
Dr Amir Khan refers to weight loss injections such as Mounjaro and Wegovy. These medications belong to a class of drugs called GLP-1s, which are incretin hormones naturally produced by the body. These injections work in three primary ways to help manage weight: slowing gastric emptying, insulin regulation, and brain signaling. They delay the movement of food from the stomach into the small bowel, helping individuals feel fuller for longer. For those with type 2 diabetes, the drugs signal the pancreas to produce more insulin in response to food, aiding in carbohydrate breakdown. The most significant effect occurs in the brain, where the drugs suppress the hunger hormone ghrelin and stimulate the fullness hormone leptin, effectively reducing food cravings.
