ABSTRACT
This chapter reviews the role of muscle in the altered metabolism that is seen with obesity. It describes the differences in muscle carbohydrate, lipid, and energy metabolism between lean and obese individuals. The chapter presents evidence for a hypothesis that disturbances in muscle-lipid metabolism may cause a person to be predisposed to become obese and provides testable hypotheses that may lead to understanding the underlying mechanisms of obesity. The metabolic syndrome is a condition characterized by hyperinsulinemia, hypertension, visceral obesity, dyslipidemia, and glucose intolerance, which leads to increased risk of coronary-artery disease and type 2 diabetes. Obesity is generally accompanied by insulin resistance, which is manifest as fasting hyperinsulinemia. The proinflammatory cytokine tumor necrosis factor alpha has also been proposed as a link between adiposity and the development of insulin resistance. Transport of fatty acids into the cell is a dynamic process upregulated by both contraction and insulin stimulation.
