ABSTRACT
The endocrine control of metabolism is designed to provide both rapid and long term adaptations to food intake and metabolic demand. This chapter focuses on glucocorticoids and thyroid hormones. However, these hormones act to regulate fuel flux in concert with epinephrine, glucagon, insulin, and growth hormone. The carbon backbones of glucose, fatty acids and amino acids can all potentially be used to form adenosine triphosphate through oxidation to carbon dioxide. These backbones can be stored as glycogen, fats, and proteins, and can be converted to fuel as needed. Regulation of appetite is a complex and incompletely understood process, in which both hormones and blood fuel levels play a role. Abnormally high or low levels of the pituitary, adrenal, and thyroid hormones lead to changes in appetite. Thyroid hormones increase insulin secretion indirectly, by increasing the metabolic rate. Hyperthyroidism can cause a diabetic state over time, probably due to the demand on insulin secretion secondary to the increased metabolic rate.
