If you want to gain weight, you'd better start with diet. In our daily diet, we should ensure that we eat enough nutrients and a lot of high-quality protein, such as meat and eggs, fish, milk, soybeans and bean products, adequate vitamins and fresh fruits and vegetables. Daily physical exercise is also essential, to ensure adequate sleep, a regular life, try not to stay up late. In addition, you can check what causes weight loss, whether it is because of your own eating habits, or because of gastrointestinal malabsorption, or other diseases of the body. Find the reason and prescribe the right medicine.