On the eve of his album release, American Idol champ Ruben Studdard was admitted to a Birmingham, Ala., hospital on Monday for exhaustion, a rep for his record label tells PEOPLE.
The singing sensation, 26, will likely remain in the hospital through the end of the week.
Studdard's gospel album I Need an Angel hit stores on Tuesday. But all promotional appearances for the new disc have been cancelled, along with his concert dates in Atlantic City on Nov. 26 and 27, which will be rescheduled.
Studdard, who beat out Clay Aiken to become the second American Idol winner, told PEOPLE earlier this month that he had decided to modify a diet that he is chronicling for TV's "Extra."
The then 449-lb star initially chose to follow a low-carb, low-cal, medically supervised meal plan and display the results on the show. But "I didn't have time to go in every day to meet with a nurse like the diet required," Studdard said.
Instead, he switched to a home-delivery meal plan that includes three weekly workouts with a fitness trainer. He had shed more than 20 pounds prior to entering the hospital, according to a source with the show.