Severly obese people will stay on these diets indefinately. They often lose hundreds of pounds. But they aren't concerned with what weight they lose, muscle or not, they just need to lose the fat. But for bodybuilding, in general you stay on until you reach your goals. I've done CKD before, and the transition to regular food can be rough. You will be hungry for awhile. Ephedrine or some other type of appetite suppressant may help.