Fad diets like the Atkin’s, blood type, cabbage soup etc. eliminate one food group from the diet which is unhealthy over a period of time. They are not at all sustainable as they are illogical and non physiological. They are de-motivating, unsatisfying and fatigue sets in over a period of time. They cannot become a lifestyle and even if made, would make one resort to binge eating later or cause malnourishment in some form or the other.
It is best to follow a sensible meal plan with healthful choices and enough exercise.