Heidi KlumSupermodel Heidi Klum reveals in the December issue of Self that the secret to keeping wrinkles at bay isn't Botox -- it's a few extra pounds.

"The ultimate beauty secret for a woman getting older is, Don't be too thin! It is always better to have a little meat on your bones. When you are just muscle, you end up being gaunt in the face, and that makes you look older by five or 10 years," Klum tells the mag.

But that doesn't mean getting lazy and avoiding workouts.

"One of the best parts about season eight of 'Project Runway' being taped in New York City was that I went running every morning. I had a watch that counts the miles and the little thing you put on your shoe that measures each step. Over seven weeks, I ran 120 miles! I don't love running, but I do like to see everything getting tighter and toned."