In anorexia, undernourishment and low body fat stores signal to the brain that the body is undernourished, leading to the shutdown of ovulation and loss of menstrual cycles.

“One of the classic symptoms of anorexia is a loss of menstrual cycles, loss of periods. And the reason for that is when the body is undernourished, the body fat stores, send signals to the brain to inform that the body is undernourished, or they turn off the signals that say, look, there are enough body fat cells out here to support healthy metabolism. And therefore let's shut down ovulation, literally signal sent from the fat and muscle to the brain and the brain, the hypothalamus and pituitary will send signals down to the ovaries, or they will turn off the signals heading to the ovaries to deploy eggs, to maturation of eggs in the follicle, et cetera.”