Jeremy Clarkson, 65, shares uncomfortable side effect of ‘astonishing’ weight loss jab
6 January 2026, 15:47
Jeremy Clarkson reveals the unexpected ways the popular weight loss jab has affected him beyond shedding pounds.
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Jeremy Clarkson has shed three stone thanks to the weight loss drug Mounjaro, but the presenter says the results have come with some surprising side effects.
In a new interview with The Sun, the 65-year-old revealed that while the increasingly popular medication has helped him slim down, it’s also brought unexpected changes that few people talk about.
The Clarkson's Farm star admitted that since starting the injections, he’s noticed differences in his mood, mental sharpness, and even his feet.
“I find myself doing Hot Seat [Who Wants To Be A Millionaire?], thinking: ‘Oh [expletive], I should have said that, but too late now’. But who’s to say I wouldn’t have thought that when I wasn’t on [Mounjaro]?” He said.
“Constipation? No, I don’t have that. Diminished libido? I’m 65, it’s hard to know what’s causing that. I’ll ask [my wife] Lisa when I get back home.”
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Clarkson explained that his weight loss had taken place over six months but had recently plateaued. Even so, he said the benefits have been worth it.
The Clarkson’s Farm presenter added: “I’m nearer to [David] Gandy now than I was a year ago, in the same way that tectonic activity means that South America is moving closer to Australia – not by much. But I can go much further, I can take the dogs out for longer now, so it keeps her happy. I’m much healthier.”
Jeremy Clarkson reveals he's on Mounjaro at the NTAs
Among the more unusual effects, Clarkson also revealed that his shoe size appears to have changed. “The shoes I was wearing last year are falling off me as I’m walking around. I think I might be the first person in the world to lose weight on my feet,” he joked.
The once-a-week injection, known by its generic name tirzepatide, has become one of the most talked-about weight loss drugs in the world. It works by mimicking two hormones in the body — GLP-1 and GIP — that help regulate blood sugar and suppress appetite.
Originally developed to treat type 2 diabetes, the drug is now being prescribed more widely for weight management.
Dr Angela Kwong, a GP with a special interest in obesity management, explained the drug's effects to HELLO!:
“Mounjaro is approved in Australia for the treatment of type 2 diabetes, weight management in adults with obesity, or those with weight-related health conditions, and most recently, obstructive sleep apnoea in adults with obesity.”
Speaking about possible side effects, Kwong added: "The most common side effects are gastrointestinal, nausea, vomiting, constipation, bloating, diarrhoea, and a reduced appetite.
"These tend to be mild and improve over time as your body adjusts to the medication."
The adjustment period for side effects varies between individuals, but subsides once your body gets used to the medication.
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