The good news is, you can have enviable abs like Gwyneth Paltrow, Jessica Alba and Jennifer Aniston, maybe even in time for summer bikini season. The bad news? You are going to have to work hard and maintain a strict diet if you want a lean, mean physique like Hollywood’s healthiest leading ladies. From Pilates and CrossFit to gluten- and sugar-free diets, stars are spilling the secrets of their flat ab success.