The caloric value of fat is 9 kcal/g, which means that 1 gram of fat can produce 9 kcal when burned. So 400 calories is 400 kcal, which is roughly equivalent to 45 grams of fat. Carbohydrates, fats and proteins are the main sources of calories in the body, with fat having the highest calories, much higher than those of carbohydrates and proteins. Therefore, if you want to control your weight and achieve weight loss, you must reduce your total calorie intake. In particular, it is necessary to reduce high-fat foods, reduce the intake of fried foods, refined and processed foods, and high-sugar foods in order to reduce the total calorie intake. It is also necessary to increase the total calorie consumption, only when the total calorie intake of the human body is lower than the total calorie consumption for a long time, the weight will be gradually reduced to achieve the purpose of weight loss.