Simon Cowell turned to veganism for the sake of his son.

Simon Cowell

Simon Cowell

The 59-year-old entertainment mogul has shed 20lbs since going on a strict vegan diet that restricts him from "pretty much all the things [he] loved", and has now said his decision to cut out foods such as dairy, sugar, bread, gluten, and meat came as he realised he wouldn't be able to "catch up" with his five-year-old son Eric if he continued eating poorly.

But Simon - who has Eric with his girlfriend Lauren Silverman - insists he hasn't completely cut everything unhealthy out of his life, as he says he still drinks and smokes, but no longer eats junk food.

Speaking during an appearance on 'The Ellen Degeneres Show' on Tuesday (17.09.19), he said: "I went to see this doctor in London. We did some tests. And then a month later he said, 'You have the worst diet I've ever met from any patient.' So I went, 'Okay, out of the smoking, the drinking, and diet, what do I have to drop?' And he said, 'The diet.' So I said, 'I'm in!'

"It was easier than I thought, and part of the reason I did it was because of Eric. I realised if I didn't sort myself out physically, I wouldn't be able to catch up with him. Because the minute he gets up to the minute he goes to sleep ... their energy, you forget, at five-years-old, is phenomenal."

The 'America's Got Talent' judge previously said he'd named his diet the Eric Cowell diet after his son, because the tot loves to munch on raw vegetables.

He said: "It's like the Eric diet because he actually, apart from ice cream, he actually likes water. I mean, who likes water? And his raw vegetables. So I'm on like, the Eric Cowell diet."

Simon also admitted that whilst he's yet to allow himself a cheat day, he is frequently tempted by pizza.