When you lose weight, your body will increase the absorption rate, because you reduce the food intake to make up for the lack of energy. Moreover, being fat has a memory. When you lose weight, fat is converted into sugar to provide energy, and fat cells become smaller. When you suddenly eat something, it will strengthen absorption and restore its original size. Because it will get bigger after a quick recovery, and you will look fatter. This is scientific, which is why people tend to gain weight after losing weight.