Q: Is it true that when you stop going to the gym, you grow fatter than you were?
A: If you stop exercising but continue eating the same as before then yes, over time you will slowly gain fat since you will be consuming the same calories as before but not burning as many as before. This would be a fairly slow process and if you are simply taking a break from the gym for a week or two, then I wouldn't worry about adjusting your calories at all. But if we are talking about not exercising for a month or more, then it may be a good idea to decrease calories a little to prevent fat gain.