It depends on how long the subject has stopped training. If it is only one month, the impact will not be too great, but after three months, some changes can be seen. Muscle loss is one thing, and easy accumulation of body fat is another. Therefore, the subjects still need to pay attention to their diet, but there are also gratifying aspects, that is, muscle recovery will be faster and fat loss will be easier after resuming training. So the subject can't exercise for some reason, so don't take it too seriously. As long as he resumes training, he can still get back into shape.