This module explores the biochemical foundations of metabolism and the role of macronutrients in endocrine function and metabolic health. It covers insulin physiology, insulin resistance, glucose metabolism, and hormonal regulation of appetite through leptin and ghrelin. The module also introduces key metabolic pathways, including AMPK and mTOR, and their roles in energy balance, growth, and tissue repair. It further examines fat storage physiology, visceral fat, inflammation, and the influence of hormones such as insulin, estrogen, and cortisol on metabolism.