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

The 59-year-old entertainment mogul has shed 20 pounds since going on a strict vegan diet that restricts him from “pretty much all the things [he] loved”, and he has now said his decision to cut out foods such as dairy, sugar, bread, gluten, and meat came when 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, 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.”