Do you have any complaints? If you feel fit and energetic then do not worry. Try to exercise every day, and do not overeat. Eat only healthy and balanced diet
. Avoid outside food / junk food / processed food and beverages. Unhealthy food may let you gain weight but they carry along a lot of health problems. Learn Yoga and pranayam which can improve your metabolism and thereby helps natural weight gain. You can contact me if needed.