Proper combination of protein , carbohydrates and fats should be included in the diet to help in weight gain . It is important to meet the demand for adequate protein to build muscle and gain weight. A variety of nuts , milk and milk products will provide the necessary energy to the body. If you want to increase the amount of drink, you have to increase your appetite first. Drink digestive drinks to increase appetite. Drink 6 to 8 glasses of water throughout the day. However , do not drink water just before eating or in between meals . This destroys the appetite. And , do some physical exercise , sleep well. Especially quit smoking , inshallah it will work.