Energy Constraints on Human Health

Evolved limits to the human energy budget force the body-brain system to operate an economy of energy. To survive and thrive, an organism’s limited internal energetic resources are dynamically reallocated by energy constraints that force trade-offs from organelle-to-organism. We propose that energy trade-offs occur between three main classes of processes: 1) Vital, 2) Stress, and 3) Growth, Maintenance and Repair (GMR). Competing demands for these processes exist within a hierarchy of energy needs where more “urgent” vital- and stress-related functions are prioritized by actively or passively suppressing longevity-promoting GMR processes. Integrating evidence from physical bioenergetics, physiology, and evolutionary theory, we highlight the flexible reallocation of resources between these processes over time, where balancing periods of hypermetabolism with rest emerges as a core determinant of health. The Energy Constraint (EC) model of human health explains how stress-related processes increase disease risk by chronically suppressing GMR, and how GMR-promoting activities including sleep and exercise recovery promote health. This model provides an energy-based framework to support optimal development and resilience across the lifespan.