This method of losing weight is really fast because of early fasting, but it has side effects, which will affect health to some extent. Losing weight in this way consumes all the fat and calories stored in the body. The human body is the most sophisticated machine. Stimulated by such external conditions, the body's default response is to enter an extraordinary period. After consuming calories and fat for 2 1 day, the body will accelerate and double the absorption when it starts to absorb calories and fat again, so as to prevent the body from living without energy when similar situations happen again. So it will rebound badly.