How the body maintains homeostasis
The brain-derived neurotrophic factor (BDNF) is a protein that regulates neuronal development and neuroplasticity. It also plays a role in learning, memory, and the hypothalamic pathway that controls eating behavior and energy homeostasis. BDNF amplifies neurotransmitter responses and promotes synaptic communication in the enteric nervous system. Low levels of BDNF are found in patients with Anorexia Nervosa and some comorbid disorders such as major depression. Exercise increases BDNF.
https://en.wikipedia.org/wiki/Anorexia_nervosa
https://en.wikipedia.org/wiki/Anorexia_nervosa