What is the Origin of Energy Substrate Selection?

A term central to the study of metabolic flexibility and bioenergetics, describing the dynamic nature of fuel utilization in response to nutritional and hormonal status. The ability to efficiently switch fuels is crucial for maintaining energy balance, preventing chronic hyperglycemia, and optimizing insulin sensitivity.

What is the Mechanism of Energy Substrate Selection?

Insulin promotes glucose uptake and storage, effectively selecting glucose as the primary fuel source for most tissues, while simultaneously inhibiting fat breakdown. Conversely, during periods of fasting or low-carbohydrate availability, falling insulin and rising glucagon/catecholamines promote lipolysis and hepatic gluconeogenesis, shifting the selection toward fatty acids and subsequent ketone production for energy.

Energy Substrate Selection

Meaning

The highly regulated physiological process by which the body’s cells, particularly those in muscle, liver, and brain tissue, dynamically choose between utilizing glucose, fatty acids, or ketone bodies as their primary source of adenosine triphosphate (ATP) production. This metabolic flexibility is heavily regulated by key endocrine hormones like insulin, glucagon, and catecholamines, and its efficiency is a key marker of metabolic health.