The 28-year-old beauty added: "I have an amazing trainer, Jason Walsh, who I work with two or three times a week. We do lots of circuit and strength training, especially for my legs and back because it's quite weak from years of gymnastics. I concentrate on making everything strong, and you can't do that with just cardio. I strength-train one day, and I'm not talking heavy weights, just a little."
Biel also revealed she was more carefree about her diet during weekends. She said: "When I'm working and I eat healthily all week, I then give myself one day - usually Sunday - when I just eat what I want. You have to, otherwise your mind goes a little nutso."