"'Oh, he's had a gastric band fitted'- but I haven't. If I had, I would admit to it. This diet is all about what you put into your body," the Britain's Got Talentjudge told Best magazine.
"I met this doctor in LA and he told me my diet was appalling and I had to cut out fatty foods and certain drinks.
"If I had, I would admit to it," says the Britain's Got Talent judge. Photo / Getty Images
The musician mogul lost 10kg after adopting a vegan lifestyle.
"I could see the difference. Cutting out sugar made a massive difference. The first few weeks were difficult, but then I actually stopped craving sugar."
Earlier this month the father of one took to the red carpet to show off his trimmer figure, but fans were shocked by his appearance.
Cowell looked drastically different in August 2018. Photo / Getty Images
"He looks like a very bad lookalike of himself," one wrote on Twitter.
"Someone should check Madame Tussaud's (to see) if they are missing wax sculpture," wrote another.
According to The Sun, the 59 year old was instructed to make "drastic lifestyle changes" after falling down the stairs in the middle of the night in October 2017."
He was reportedly rushed to hospital and told he had to stop bingeing on sausage rolls, hamburgers and his favourite jam tarts made by his personal chefs.
Doctors also warned against him living "like a vampire" by staying awake all night every night until 8am - saying it had to stop.
"Within 24 hours I changed my diet and I've not looked back since. You feel better, you look better, the America's Got Talent judge told The Sun earlier this year.