Final answer:
The adrenal gland cortex secretes glucocorticoids, such as cortisol, which help the body to utilize fat as a fuel source by promoting the breakdown of triglycerides into fatty acids and increasing glucose levels through gluconeogenesis.
Step-by-step explanation:
The adrenal gland cortex secretes glucocorticoids which encourage the body to use fat as fuel. These hormones, particularly cortisol, are released in response to stress and regulate the metabolism of fats, proteins, and carbohydrates. Glucocorticoids promote the breakdown of stored triglycerides into fatty acids and glycerol while also increasing the levels of glucose and fatty acids circulating in the blood through gluconeogenesis and other metabolic processes. During long-term stress, besides the release of fatty acids, cortisol also promotes the catabolism of glycogen to glucose and the breakdown of muscle proteins to amino acids, which can be used as alternative energy sources.