Well, there are two options. In the first case, roughly speaking, if you get fat, then you will need to follow a certain diet. But, do not kill yourself and do not eat "after six", etc. It's very simple, eat more protein foods, and less food that contains a large amount of carbohydrates. And of course, go to the gym and train. In the second case, if you are thin, like me, then you better eat a lot of carbohydrates. That is, food that contains a large amount of carbohydrates. Train again. Better, three times a week with a duration of an hour, well, a maximum of an hour and a half. No more. Better yet, go to a nutritionist and physical trainer. preparation, and consult with them. I'm sure they will help you. Good luck!
IMHO. First of all, you need to restore psychological health, and then "physics. But one cannot exist without the other, therefore, unambiguously combine. Read books on this topic. Good luck, friend!