The caloric value of fat is 9 kcal/g, which means that 1 gram of fat burning can produce 9 kcal. 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 for the body, with the highest calories from fats being much higher than those from carbohydrates and proteins. Therefore, if you want to control your weight and achieve weight loss, you must reduce your total calorie intake. Especially reduce high-fat foods, reduce the intake of fried foods, refined and processed foods, and high-sugar foods to reduce the total calorie intake. In addition, we must increase the total calorie consumption. Only when the total calorie intake of human body is lower than the total calorie consumption for a long period of time, the weight will be gradually reduced and the purpose of weight loss will be achieved.