He also revealed he goes to bed at midnight and is up at 4:00 a.m. every day, reports Female First UK.
He told The Hollywood Reporter: "I don't eat and I don't sleep. That's also the trick (to staying in shape). I often find myself trembling and think: 'Oh I should get some calories in me'."
As per Female First UK, Manilow revealed he's managed to quit smoking after years of puffing through three packs a day and now works out with a personal trainer every morning. During the interview, Manilow also admitted he thought he should have died six years ago because so many of his relatives passed away at the age of 74 - so he's amazed to still be around at 80.
He explained: "My family, most of them lived until 74 - so when I hit 74, I thought: 'This is the end.' But it didn't happen. It kept on going. I kept going on the road. I kept on making records. I mean, when does my body give in?"
He told Parade: "I never sleep. "I get four hours a night. That's all I really need. It's been that way for years.”
He added: "When you start out in New York, you're always a New Yorker. "I just have a lot of energy; I talk fast, I think fast. Maybe it's because New Yorkers are always moving, scrambling to get a seat on the subway or something”.
