Symptoms of anorexia nervosa include loss of muscle mass, low heart rate, low blood pressure, fainting, lanugo, loss of bone density, disrupted gut and immune functions, and loss of menstruation in females.

“You can see all sorts of very troubling symptoms of somebody who's been anorexic for some period of time, a general loss of muscle mass because they're ingesting fewer calories than they burn. Muscle is very metabolically active. They tend to lose a lot of muscle mass. They will have a low heart rate. This is the body and brain's attempt to lower energy output. They will have low blood pressure. They'll sometimes have symptoms like fainting. They will have sometimes even hair growth on the face, something called lanugo, which is essentially the body's attempt to insulate the body because of loss of body heat. When you're that thin. Loss of bone density, osteoporosis, loss of periods in girls and women, and all sorts of disrupted gut and immune functions.”