Welcome to Health care magic. Thank you for posting your question. I can understand your concern. At your height , ideal weight is around 120 lbs. Let me help you out. First of all do not be depressed so much. You have to be patient. Some of us have a fast rate of metabolism . That hinders us from gaining weight. But with a bit of planning , you can improve . To gain weight, you need to eat more calories than your body uses each day. You need to do this regularly. It s not enough just to have occasional extra snacks Gradual weight gain is always advisable. An increase in 500 kcal per day can result in increasing the body weight by 0.5 kgs per week. Eat plenty of healthy fats. Eat your egg yolks, meat with animal fat, coconut oil, and other healthy fats. Increase caloric intake - of the healthy kind of course. So those bananas count well here. Chew the food properly to improve digestion. Keep a track of your weight gain as this is essential; it is healthy to increase approximately 5 to 6 kgs weight per month. With this diet add physical exercise for 20 minutes a day. Stick to this routine for 6 months. Do not worry. Have patience. The right combination of healthy food, exercise, right breathing, rest and sleep go a long way in a happier and healthier you. Post any other question. We will be happy to help. Have a nice day. Regards.