The coating on the Vicodin and the Valium he'd been taking "for years" left him with a hole in his stomach, which would keep him up all night if he didn't fill it with junk food.

He tells Men's Journal magazine, "I was constantly eating - and eating badly."

Eminem's pill addiction led to an overdose in 2007 and following a rehab stint, the 42 year old switched one obsession for another - and began exercising.

He continues, "When I got out of rehab, I needed to lose weight, but I also needed to figure out a way to function sober. Unless I was blitzed out of my mind, I had trouble sleeping. So I started running. It gave me a natural endorphin high, but it also helped me sleep, so it was perfect.

"It's easy to understand how people replace addiction with exercise. One addiction for another but one that's good for them. I got an addict's brain, and when it came to running, I think I got a little carried away... In the end I got down to about 149 pounds. I ran to the point where I started to get injured. All the constant pounding from the running began to tear up my hip flexors."

Eminem began to incorporate work-out DVDs into his routine and now he feels he is where he wants to be, as far as his health is concerned.

He adds, "I guess I'm pretty compulsive working out. I feel like if I step away from it for too long, if I have a crazy week and take a five-day break, it'll be like starting over.

"I'm afraid that if it goes beyond that, I might lose the motivation. Once you're at a place where you've made progress and you've got some time invested in it, you don't wanna quit and give up what you started."