In nutrition, calories generally refer to the amount of energy provided by food to the human body, and are often referred to as calories, “kcal” being its unit. In daily life, its existence is not only to ensure that the human body to carry out growth and development, basic metabolism, physical activity and other physiological needs, but also for the fitness crowd, also through the calculation of calories, skilled grasp of their own health status. The need for calories varies from person to person. For example, maternal and lactating women need more calories than women of the same age, and older people need fewer calories than younger people. Calories mainly come from foods rich in protein, fat and carbohydrates. Different foods contain different nutrients and provide different calories, so we need to pay attention to reasonable intake. In addition, the daily calorie intake should be balanced with the calorie consumption, so that there should not be a shortage of energy, nor should there be a surplus of calories leading to hoarding. If you consume too little, it will lead to malnutrition, and if you consume too much, it may cause excess nutrition and even cause diseases such as obesity.