Liv Tyler says she spent years worrying about her weight.

Unlike Nicole Richie, however, she was able to put a stop to it.

The reason? When she became a mom, Tyler's perspective changed.

"I've been a model and actress since I was 14, so I've been on a diet my whole life," the actress, 29, says in the March issue of Glamour.

"But once I gave birth, I didn't want to think about myself or feel insecure about my career; I wanted to think about my child. So I stopped worrying about diets."

It's an admirable step for such a talented star. Hopefully, Peter Sarsgaard has similar priorities now that he's the father of baby Ramona.

Still, the mom of 2-year-old Milo (with husband Royston Langdon, 34) says she recently lost 10 pounds without even trying while filming the thriller The Strangers in South Carolina.

While no one would compare a slender Liv Tyler to that behemoth Brooke Hogan, Steven Tyler's daughter admits she started pigging out pretty damn hard.

"I've been eating like a pig. I think it's because I hired this chef on the set of Strangers to cook for me, and I ate a lot of vegetables and protein. Filming was also incredibly intense: We were supposed to be out of breath in every scene, so I would run around the stage to achieve that. I just went to Marc Jacobs and I bought a red dress in a size 4. I've never been a size 4 in my entire life!"

But she's cool with it.

Tyler says she's interested in being herself - and to that end, she took a two-year hiatus from film work so she could devote time to being a mom, and experience she describes as "transformational."

"Is that a word?" she asks with a laugh, then adds:

"Getting pregnant and caring for a baby gave me a confidence I'd never had before. I really felt I'd done something well, and I can't say that about anything else in my life."

You hear that, Britney Spears?

There's more to life than commando partying.