Chunky American Idol judge Randy Jackson (search) has had gastric bypass surgery in an attempt to lose weight.

Inside Edition (search) is reporting that Jackson, 46, underwent a procedure called the Fobi Pouch last week at the Center for the Surgical Treatment of Obesity in Southern California.

"The patients who undergo this kind of procedure are usually morbidly obese," surgeon Dr. Basil Felahy told Inside Edition.

"By giving [the patient] a small pouch which is going to be his stomach from now on, the main stomach and bowel attached to it is bypassed."

Jackson, featured last March in People magazine, said he was concerned about his weight and had lost 20 pounds by eating smaller portions and working out several times a week.

During the run of American Idol (search), Jackson once criticized a contestant for his weight, telling him, "You take that home and work on it and you come back and show me that you've lost probably 100 pounds and get your look together."

Jackson, who co-judges American Idol with Simon Cowell (search) and Paula Abdul (search), is expected to return for the show's third go-round in January.