Carrie Underwood is so determined to keep her slim physique she keeps a diary of everything she eats.

The Play On hitmaker keeps a rigorous workout regime too, admitting her good looks don't come without a price.

Underwood tells Us Weekly magazine, "I've kept a food journal for three years, and work out four to six days a week, even if I just get in 30 minutes on a bike or the treadmill.

"I may not be perfect but I work hard for what I got." (c) WENN