Sept. 17 (UPI) -- Simon Cowell says his son inspired his healthy new diet.
Cowell said he drastically changed his diet after seeing a doctor and undergoing tests in London.
"It's pretty much all the things I loved I can't now eat. No dairy, no sugar, no bread, no gluten, just lots and lots of things. No red meat," the star told host Ellen DeGeneres.
"It was easier than I thought," he added. "Part of the reason I did it was 'cause Eric is five this year. I realized that if I didn't sort myself out physically, I wouldn't be able to catch up with him."
Cowell had lost 20 pounds as of August, when he spoke to Access Hollywood on the red carpet at the America's Got Talent live shows.
"The secret is don't follow one of the fad diets," he advised fans. "You just got to cut out the obvious. And once you get used to it, you feel better -- my memory's better, I feel better. I didn't find it difficult. I can still drink beer, so I'm happy."
Cowell is a judge on America's Got Talent Season 14, which will air its live finals Tuesday on NBC. Benicio Bryant, the Detroit Youth Choir, Emanne Beasha, Kodi Lee, V. Unbeatable and other finalists will perform.