Because of increased muscle, certain forms of exercise, such as strength training, can cause weight gain. Water retention is another factor in weight gain. Experts agree that this is part of a recovery process and is able to get glycogen into the body more effectively. Many people eat more after exercise to make up for the calories they’ve burned. If you’re worried, have your body fat tested by a personal trainer at the gym, or get regular measurements of various areas of your physique. To find out how much calories you’re eating, use this diary or the website Calorie Count.