You can't do this, your health will be damaged. Now that you are young, you will find all kinds of pain when you are old. Although you lose weight quickly during menstruation, you can't go on a diet, which is not conducive to the discharge of dirty blood and blood, and the endometrium falls off. It may lead to decreased menstrual flow and lack of nutrition in the body. Menstrual nutrition must keep up, and eating sweets during menstruation will not make you fat. If you really want to lose weight during this period, you'd better do it.