Heidi Klum: "My Son Eats Three Bananas a Day"

Heidi Klum stars in the Victoria’s Secret Fashion Show, which airs tonight.

“I’m not going to be wearing too much,” she teases.

How did the mom of three, whose youngest son, Johan, recently turned 1, get into shape?

“I don’t do too many things,” the Project Runway host/supermodel says. “I’m very active. I eat really healthy. I like healthy food; I enjoy it. I like things that are good for me. I splurge, but not a lot.”

Heidi, 34, is also mom to Leni, 3, from a previous relationship with Flavio Briatore, and Henry 2, by hubby of two years, Seal, 44.

What surprises her about being a mom?

“Sometimes I say something and weeks can go by and all of a sudden that comes out,” she says. “I’d forgotten it already, and I’m like ‘why did she just pull that one out?’ They just keep a word or they keep a certain thing and hold onto it. Then all of a sudden, two weeks later, they break it out.”

How does she handle discipline? “I try to be fun, but I also try to be hard in places where I have to be.”

What’s in her diaper bag? “I need diapers in different sizes,” she says. “There’s always wet wipes, there’s milk, there’s water, there’s goldfish, there’s tons of things you have to bring like bananas. Henry eats three bananas a day.”

Catch this supermom in the Victoria’s Secret Fashion Show, which airs on CBS at 10 p.m. ET/PT.