First I will start off with the psychical effects it has, and then the mental effects it has.
Anorexia can cause long term harm to the body, due to the lack of fuel that enters the body. Without food the nerve system starts to shut down. Because of the lack of food brain cells will usually decrease. The body needs nutrition and without it, it starts becoming a serious neurological issue. In deeper depth, the body starts eating its own muscle away. The neurons in the hypothalamus have also been discovered to eat its own proteins and organelles when deprived of nutrients/food. Due to not enough calories it will likely not be able to prevent thiamine deficiency. Without thiamine the brain starts to slowly die, and the body can’t produce it itself. Physical changes are; hair, skin and nails.
The emotional effects of anorexia consist of low-self esteem, along with perfectionism. Depression and anxiety, anxiety and irritability around meal time. Obsessive concerns and rules about dieting, body shape and weight. The intense fear of gaining weight or ongoing behavior that does not enable weight gain.