Chaka Khan received rave reviews for a figure-flattering catsuit she wore last week during a performance on "American Idol" and now she's revealing the secret to her slim and trim success. The soulful chanteuse admits she relied on extreme dieting and fasting to obtain a 60-pound weight loss.

The "I'm Every Woman" creator said she stuck to a liquid diet for several months. "I started out fasting ... for four months. I did nothing but liquids; me and my VitaMix were best friends," Khan, 59, told "Access Hollywood."

She even disclosed details of the liquid nutrients she consumed during her four-month extreme dieting plan. "In the morning I'd have a high protein smoothie and in the afternoon I'd have a vegetable smoothie and in the evening I'd have another protein smoothie," she revealed.

Earlier this month, Khan stepped out at the Kennedy Center Annual Gala in Washington, D.C., showing off her dramatic weight loss in a black jumpsuit.

See Chaka Khan's Catsuit & Red Carpet Look on "American Idol"