Carbohydrate is also called sugar, and carbohydrate food refers to sugar and sugary food. Carbohydrate is the most direct energy source of human body, and the excess carbohydrate will be converted into fat and stored by the body, so friends who want to lose weight should control the intake of carbohydrate. However, if the carbohydrate content in the body is not enough to meet the energy consumption, it will consume protein, that is, muscle tissue to provide energy, so friends who want to gain muscle can appropriately increase the carbohydrate intake. Carbohydrate (sugar) is mainly divided into monosaccharide and polysaccharide. According to the absorption degree of human body, monosaccharide is the easiest to absorb, because carbohydrates (polysaccharides) ingested by human body need to be digested in the body to become monosaccharides before they can participate in body metabolism. For fitness friends, usually the carbohydrate intake is mainly polysaccharide, because the intake of monosaccharides (such as candy bars, carbonated drinks, etc.) leads to a rapid increase in blood sugar content in the body. At this time, insulin will be secreted to reduce blood sugar content, which is why the more you eat sugar, the easier it is to get hungry. If you participate in fitness training at this time, the energy supply is obviously insufficient. However, polysaccharide food can only provide energy by being digested into monosaccharide by the body. The process is relatively slow, and the blood sugar content increases steadily, which can continuously provide the body with energy needed for fitness. The content of polysaccharide is high in staple foods such as rice and flour. While ingesting carbohydrates, other nutrients such as protein, lipids, vitamins, minerals and dietary fiber can be obtained. However, ingesting monosaccharides or disaccharides such as sucrose can not supplement other nutrients except calories. The carbohydrate in food is mainly lactose (monosaccharide and disaccharide), followed by sucrose and a little starch (polysaccharide). Breast milk contains the most lactose and belongs to disaccharide. Fruit contains a lot of fructose and glucose, which are monosaccharides and easy to absorb. Cereals and wheat contain starch, which is a polysaccharide, which is decomposed into maltose and glucose in the digestive system of the body and used by the body. However, cereals also contain other nutrients, so the nutritional value of cereals and beans is higher than that of pure sugar foods. Beans also contain protein, iron and B vitamins, which is better than eating simple sugar.