Chrissy Teigen, even as she posed nude for the cover of Women's Health U.K., insists she's always had to watch what she eats.

Jon Legend's better half told the magazine she has to work overtime to keep her body in the enviable shape it always seems to be in.

"I used to take pride in the fact I didn't have to work out, and then I hit that age where you have to," the 29-year-old Sports Illustrated model said.

"I want to drink champagne and have hearty dinners, so I would rather work out for an hour and be able to do what I want. I've always had to watch myself. My family is not naturally thin and we put on weight quickly. I find low-carb works for me."

Teigen has a cookbook due out next month and hints the timing of the release couldn't have come at a better time for her. She says she gained 11 pounds while working on recipes for the tome.

 "My tummy has always been my problem area," she said. "I've never seen an ab, no matter how many crunches I do."

One thing Teigen does insists she's keenly focused on is becoming a mom for the first time.

"I'm waiting for things to slow down, but things don't seem to be slowing down, ever, so I think, 'Just have one and deal with it,'" she said. "I'd love to have an excuse to be bigger. People will know as soon as I'm pregnant because I'll stop drinking."

Recently, rumors have percolated Teigen has been feuding with Tyra Banks behind the scenes of their new talk show set to air this fall. Earlier this week, Banks sought to refute those claims, slamming all the talk as "ridiculous gossip."