It's bound to be the greatest celebrity makeover in TV history. Weighing in at 360 pounds, "American Idol" Ruben Studdard is going on a diet, and it's all because of "Extra."

After two months of top-secret meetings between Ruben and "Extra's" senior management, Studdard agreed to make a major life change. "I think right now, for me, I need to get as healthy as possible," Ruben told us. "A little healthier lifestyle, try to work out a little more so my performances can be better."

We've assembled the "Extra" Extreme Fitness Team to make it all happen: "American Idol's" Randy Jackson will serve as Ruben's "life coach," and trainer-to-the stars Gunnar Peterson will transform Ruben's body.

Here's the extreme team plan: we're moving Ruben from Alabama to Los Angeles, where Gunnar, who's trained Hollywood's greatest, from Jennifer Lopez to Sylvester Stallone, will workout with Ruben three times a week.

And it seems this couldn't come at a better time. Studdard just celebrated his 26th birthday Sunday night and is getting ready to promote a new gospel album. "It's going to be a good happy birthday to me," Ruben confirmed.

But no one knows what Ruben is going through better than Jackson, who lost 100 pounds and plans to help Ruben with his workouts, diet and motivation. "I did my own thing about a year ago, and man, it's about trying to get healthy," Jackson said.

Tomorrow on "Extra," we have a VIP pass into Ruben's Birmingham birthday bash, with 2,000 guests, southern cooking and an all-night party.