Supermodel Heidi Klum lost her pregnancy weight thanks to her baby.

The German-born beauty modeled for a Victoria’s Secret underwear show just six weeks after giving birth to her fourth child, daughter Lou, and credits taking long walks with the infant for helping her shed the excess pounds.

“In the first two weeks after the birth I did absolutely nothing. Then I started very slowly with a bit movement. We live in Los Angeles at a very steep hillside. I walked it up and down - with a baby buggy! Then I extended this subsequently to longer walks.”

As time went on, Heidi expanded her workouts but admits she prefers working out with the infant than a trainer: “Then I called my trainer Andrea Orbeck. She comes to me a few times a week. We train with weights, we do exercises with a medicine ball and much more. To be honest - it is not really fun for me. But I think it’s important for my body.”

The 36-year-old beauty - who also raises daughter Leni, five, and sons Henry, four, and Johan, three with husband Seal - says she is “proud” she took the decision to take to the catwalk again so soon after giving birth.

She told German magazine Gala, “I have been a Victoria’s Secret angel for the past 12 years and I’m very proud of that. I made the decision at the last minute to go on the catwalk. When we were all waiting backstage and the music started my feet started to tingle. It was a lot of fun!”