Also, any large weight adjustment causes a shift in hormones, because estrogen release is partially based on your
fat cells. When you lose a large amount of weight,
estrogen automatically declines. If you stop losing this weight at a healthy weight, once your body adjusts to the new amount of hormones, you should return to normal. Another reason for lack of menstruation after weight loss is poor nutrition, related to a lack of iron, zinc and lack of healthy dietary fats.