The Hollywood hunk - who is known for his trim physique - admits he has to take care of his body but does enjoy eating "old fashioned" fast food occasionally.
He said: "I do eat healthy but there`s nothing better than a good old-fashioned American cheeseburger and fries.
"I go to In-N-Out Burger, a healthy fast food place in Los Angeles. You can have a `protein style` burger - without the bun and wrapped in a lettuce leaf."
However, the 36-year-old actor - who was previously married to Reese Witherspoon - can`t eat too many of the calorific treats because it would mean he would no longer be able to fit into his jeans - an item of clothing he is particularly fond of.
He said: "I have lots of pairs of jeans in my closet. One of my favourite brands is True Religion. I have a few pairs of those, all with different denim washes."