The New Celebrity Workout Plan: No Cardio!

Stop using treadmills, stair masters and elliptical machines.

Celebrity personal trainer Jim Karas, who has helped Diane Sawyer and Hugh Jackman whip into shape, is revealing to “Extra” that cardio is actually an enemy!

“Cardio kills your body and most importantly, it kills your weight loss goals,” Karas said. “We'd go, go, go hitting the strength training, and never touched a piece of cardiovascular exercise.”

Jim explained that is because cardio exercise decreases your metabolism, while weight training gives it a boost.

“Let's get that metabolism up, that's the key to weight loss,” he insisted.

Now the trainer is whipping singer and "American Idol" alum Kimberly Locke into shape.

“I just lost a significant amount of weight, but I hit a wall,” Kim admitted. “I'm saying, and probably everyone else out there is saying, 'What do we do?'”

The answer is interval base strength training or exercises that engage more than one body part, according to Jim in his new book, “The Cardio-Free Diet.”

The trainer also said you do not have to work out more than one hour a week, never do more than 10 repetitions of a single exercise and always eat something before you hit the gym.

If you don't follow these steps, Jim said, “You could burn muscle for energy; you never want to do that.”

Like most people, Kimberly is ecstatic about this new workout plan!