It is useful to lose weight in a short time, because the intake of carbohydrates and oils is completely cut off. Low-calorie diet is very harmful to the body. It is definitely water and muscle, not fat, that will be lost in these three days. In the early stage of weight loss, water is generally lost. Eat something else when you lose weight, otherwise you will be severely malnourished and weak. This is because the human body needs all kinds of substances to maintain vitality. If you eat a few apples a day to lose weight, the final weight loss effect is not obvious, and it may also cause other diseases. In fact, obesity is the result of not exercising; It is best to combine a regular diet with regular exercise. Sticking to exercise is the key to losing weight.