If you didn't focus on aerobic training in the gym before, and didn't consume too much muscle, the dietary calories will drop accordingly after you stop training, and protein won't rebound quickly if he eats too much.

Of course, the so-called speed is relative to dieting and taking medicine. Because if you exercise a certain amount of muscles in the gym, your basal metabolism will be improved, and you can eat more than ordinary people at ordinary times without causing rapid weight gain. However, if you are on a diet, have too much oxygen, or take drugs, in many cases, it may just be water loss. If you don't control your diet after stopping training, you will rebound faster.