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The Five Factor Diet: Created by celebrity trainer Harvey Pasternak, this diet has the kind of star-studded endorsement that Jenny Craig could only dream of. John Mayer, Eva Mendes, Jessica Simpson, Kanye West, and Alicia Keys are a few of the celebs who rave about this plan. Initially created for celebrities, the prepackaged meals are over a 5-week plan, with 5 meals a day containing 5-ingredient meals, allowing 5 cheat days, and including 25-minute workouts (5x5!). Basically if you love celebrities and the number 5 as much as Harvey Pasternak, you've got yourself your dream diet (and you may also have OCD).