Weight gain here means that the food you eat is converted into fat in the body, that is, the increase of fat. Then, among the three nutrients, carbohydrate, protein and lipid, lipid is most easily converted into fat, followed by carbohydrate and protein. Three nutrients can be transformed into each other, but it is difficult for protein to transform into the other two. Excess protein cannot be stored in the body, but will be excreted with metabolism. Therefore, in the case of a certain total energy intake, try to eat less lipids (fat, oil and cream) and carbohydrates (rice, noodles and steamed bread) and eat more protein (fish, lean meat, skim milk and eggs). In addition, it should be noted that vegetables are rich in cellulose, although carbohydrates also contain cellulose, but they are difficult to be absorbed and stored by the human body. Eating more vegetables will provide you with a feeling of fullness, so my suggestion is that vegetables should be matched.