Which hormone is involved in the breakdown of lipids?

Epinephrine plays a significant role in the breakdown of lipids, particularly during times of stress or when energy is needed quickly. This process is known as lipolysis, where triglycerides stored in adipose tissue are broken down into glycerol and free fatty acids, which can then be used for energy. Epinephrine, released from the adrenal medulla during "fight or flight" situations, activates hormone-sensitive lipase, the enzyme responsible for initiating the breakdown of fat.

In contrast, while thyroid hormone, cortisol, and insulin have roles in metabolism, their primary functions differ. Thyroid hormones mainly regulate metabolic rate and thermogenesis, cortisol is involved in maintaining blood glucose levels during stress and can influence lipid metabolism but does not directly initiate breakdown, and insulin promotes the storage of glucose and fats rather than their breakdown. This makes epinephrine a key hormone in lipid mobilization during physiological stress.