The root cause of obesity is that energy intake exceeds energy consumption. Heat comes from energy-supplying substances in food: protein (4 kcal/g), fat (9 kcal/g) and carbohydrate (4 kcal/g). The heat consumption is mainly composed of three aspects: basic metabolism, physical activity and food thermal effect. The center of weight loss is to achieve a negative balance of calories (calorie intake is less than calorie consumption). The level of basal metabolism is mainly related to the nutritional status and eating habits of the human body, so not eating after noon is essentially a very harmful way to lose weight. Physical activity and amount of exercise are not the same concept. Scientific research shows that high-intensity exercise is not conducive to losing weight. The thermal effect of food is generally 2~3 hours, which is the theoretical basis for many weight loss experts to say that eating less and eating more meals is beneficial to weight loss.