Hello, I really appreciate your decision to quit alcohol and regain your health. Having less weight does not always mean you are underweight. Being under or overweight is decided by BMI (Body Mass Index). It depends on your weight and height. You can calculate your BMI using this simple formula: BMI = Body Weight in Kilograms / (height in meter * height in meter) If the answer comes below 18.5, then you surely need to gain some weight as you need more body mass to maintain optimal health. If it comes below 18.5 for you, here are some simple ways that I can advise you to gain weight. First of all, you should join a gym nearby and start exercising regularly. There are certain exercises that can help to build muscle mass and gain weight. A gym trainer can teach you those exercises and help you gain weight. You can add more proteins in your diet to increase muscle mass as muscles are made of protein mainly. Dairy products, nuts etc are some examples. You should have at least 3 meals per day and should include high carbohydrate and high fat food too in your meals. You should not drink water before meals. Use bigger plates. Even having adequate sleep can also help in growing muscles. However, you should take care to gain weight in healthy way and not become obese or unhealthy. You should avoid drinking too much sodas. You should not overeat at any one time. Hard work and determination can make you achieve your goals. I hope this information helps. Thank you for choosing HealthCareMagic. I wish you good health. Best, Dr. Viraj Shah