Hello, Its unfortunate that you are dealing with this problem. You should ingest more energy in form of more calories with good quality proteins and nutritious food on daily basis than you use up for physical activity. Add 500 calories per day to your current requirement. Eat more. Eat 5-6 meals per day. Avoid skipping any meal. Increase your portion. If you eat 2 chapattis, then have 3rd one. Eat corn,potatoes peas,banana,custard apple,chikku,mango,peanut butter,cheese, milk with 2 tsp skimmed milk powder, boiled eggs. Maintain 2 hour gap between each meal. Drink plenty of water, fruit juices, milkshakes, smoothies. Exercise daily. Exercise will stimulate your appetite,increase your energy needs and will convert extra calories into muscle. Sleeping is the best thing you could do to keep yourself healthy. Take afternoon nap immediately after lunch. Make sure you sleep for atleast 7-8 hours every day at night. Hope this helps. Take care.