Hi, Thanks for posting in HCM. I understand your concern. It is always advisable to gain weight naturally and gradually. You need to take protein rich diet by consuming egg and pulses regularly. You can supplement additional protein in the form of protein powder mixed with milk twice daily. Take moderate quantities of carbohydrate and fats in the diet. Everyday you can have calorigenic fruits like apple or banana at bedtime. Gradually, you should gain weight substantially. To avoid gaining overweight, exercise regularly to keep yourself fit and healthy. Hope the information provided would be helpful. All the best.