And, for an awful lot of people, It works. Before the crass mass market commercialization of his program, over 25,000 morbidly obese people were helped at his clinic.
Further, if you are a Gym Rat, it's the one diet you can go on, and Lose Fat, Gain Muscle, and increase stregnth, simultaneously.
I doubt that he followed that diet himself. Wasn't "The Atkins Diet" intended to be temporary as an aid to weight loss?