Hello! Thank you for writing! Masturbating 1-2x per week doesn't have any side effect. As for your weight try to eat healthy meals including: salad, fruits, vegetables, whole grain, soups, fish, chicken meat, diary, eggs, seeds, in order to get all the calories and different nutrients your body needs to function properly. Do you have other signs or complaints? Try to exercise by going to the gym, is a good choice since you can build muscles there by a specific program by a trainer and get bigger and healthier naturally. Wish you good health. Best regards.