I am 22 year old female and I am losing weight each day I have become weak due to playing games. I am underweight according to bmi index my hemoglobin is also low how can I gain weight and become healthy.

Ok. First as you play games so that you should take extra care of your health. Many reasons are there for lower hemoglobin level. The main cause is nutrient deficiency like folic acid, iron, vit c and b12.(1) take iron rich foods like tofu, lentil, spinach, dates, almond, liver, red meat, shrimp, fortified breakfast cereals, oyester etc. You can take also a iron supplement.(2) take citrus foods as it helped in iron absorption (3) take folic acid rich foods like green leafy vegetables, sprouts, wheat germ, peanut, banana, broccoli, liver, rice, dried beans etc. Also you can take supplement.(3) beetroot is known for increase hemoglobin level. It is rich in iron, folic acid as well as vitamin, minerals.(4) apple also helps to maintain normal hemoglobin level. It is rich in iron and many other healthy nutrients. And to weight gain (1) don't drink water before and during meals (2) do yoga and free hand exercise (3) add cream with your tea/coffee (4) eat more foods (5) use bigger plate (6) drink milk (7) use weight gainer shake (8) 2-3 banana each day (9) take dry fruits more (10) take quality sleep.