In an interview with Bunte magazine, the 35-year-old German beauty - who fronts one of the country's most popular reality TV shows, "Germany's Next Top Model" - said, "I was never a diet sort of person."
"But when I started to model, I knew already that I would have to watch what I ate and for example stop eating wiener schnitzel," she said referring to a traditional Austrian dish popular in Germany which consists of veal fried in breadcrumbs.
"My children are my best workout," she said, adding with a twinkle in her eye, "I am of course also busy with my husband."
Klum, married to British soul singer Seal, has come under fire for her merciless criticism of the would-be models on her show, though it has millions of Germans glued to their screens every week.
Her attacks on the young girls for their looks and figures have prompted sniping over her own appearance.
Wolfgang Joop, a well-known German fashion designer, recently said she was too fat, and that her breasts and hips were too large.
But Klum told Bunte she wasn't bothered by the critique. "Everyone is entitled to their opinion. So am I," she said.
The supermodel is rarely out of the news. Earlier this week, she wowed Los Angeles by handing out lingerie on the streets. She also recently said she wants to keep modelling until she is 80.