Boys who are born too thin, it is recommended to increase the intake of nutritious food, combined with a moderate amount of exercise, etc., if it is caused by disease, it is recommended that the first treatment of the original disease. 1. Boys who are born too thin want to gain weight, you need to increase the intake of nutritious food, staple food can eat white flour, rice, but also intake of adequate protein, eat some shrimp, milk, meat, fish, eggs and other high-quality protein-rich foods, but also pay attention to the intake of fruits and vegetables. 2. If you are too thin due to hyperthyroidism, hepatitis and other diseases, you can take anti-thyroid drugs or anti-viral drugs under the guidance of your doctor. If the spleen and stomach function is not good, it will affect the absorption of food, you can follow the doctor’s advice to take spleen pills and other drugs to regulate and promote food absorption.