Hello there. I can understand your concern. The math to gaining or losing weight is simple. To gain weight, you need to eat more than your daily required number of calories while to lose weight, you need to eat less than the number of daily required calories. Therefore you have to start counting your calories. You have to have frequent high calorie diet. On an average a adult male like you requires about 2500kcals a day therefore you need to eat atleast 3000kcals a day to gain weight. Best regards. Dr. Anil Kumar Jain.