By StyleWatch
Updated May 17, 2010 04:30 PM

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Comedian Jason Alexander unveils his new slimmed-down figure with classic self-deprecating hilarity in a new Jenny Craig commercial, airing today. “Take a look, drink it in,” he sings while clad in a skin-tight outfit. “I was fat, now I’m thin!” The actor, who signed on as a spokesman for the weight loss program in January, has since shaved off 30 lbs. from his starting weight of 198 lbs. Best known for his role as the portly George Costanza on Seinfeld, the Broadway vet, 50, came up with a his own twist to the “Full Monty” concept for the ad’s big song-and-dance reveal. “He gives me a good show,” said friend and fellow Jenny Craig spokeperson, Valerie Bertinelli, who showed off her own bikini body on the cover of PEOPLE a year ago. Appearing side-by-side with Alexander in the commercial, she says, “I was losing my voice because I was having so much fun!” –Thailan Pham