A calorie is a unit of heat that measures the nutritional energy of food as well as the energy released inside the body, thus maintaining the nutritional balance of the organism to avoid malnutrition or obesity. The heat required to raise 1 gram of water by 1 degree Celsius at 1 atmospheric pressure is called 1 calorie, which belongs to a kind of calorie unit, and nutritionally measures the calories of carbohydrates, proteins, fats and other nutrients. In normal times, calories can be used to calculate the nutritional energy of food, so as to make a choice of food intake. The WHO once published a book entitled “Calorie and Protein Intake”, which describes in detail the value of calories that the human body needs to consume in a day, in which a normal adult male needs to consume about 1,980-2,340 calories per day, while a female needs to consume about 1,800-1,900 calories per day. If the actual intake is insufficient for a long period of time, then it will cause malnutrition. However, if the intake is excessive, then it will lead to an increase in the fat content in the body, which in turn will lead to the problem of obesity. Therefore, when you eat food, you should pay attention to check the calories of food, strictly control the intake of food, eat more fresh fruits and vegetables, and timely replenishment of nutrients.