Hormone levels fluctuate when there are chages in weight - particularly in women. For most, the mesnstrual cycle is not effected, but some women experience increased activity and break-through bleeding may occur. Oters may find that their periods stop for a while. Once target weight is reached and weight loss ceases, the metabolic rate will adjust t a new level appropriate to the new weight, and the hormones will settle down and find their own pattern again. page 139...Questions and Answers. 20th anniversary edition of The Cambridge Diet book.
This upset to the totm is very common but it does settle down.
Hope that helps.
Love Mini xxx