Psychological Calories
Describes the mental effort and energy required to process and cope with the various stressors and demands of daily life, and how this can lead to decision fatigue and burnout.
Origin
The exact origin is uncertain, though the concept draws on research into cognitive load, decision fatigue, and mental energy depletion. The metaphor parallels physical calories: the human brain consumes 20–25% of daily energy needs despite being only 2% of body weight, relying almost exclusively on glucose. The prefrontal cortex requires significant energy to process decisions, with different mental tasks consuming varying amounts. As mental resources deplete, the brain conserves energy by taking shortcuts or avoiding decisions, resulting in reduced self-control and increased reliance on heuristics. The term "psychological calories" captures how mental effort—like physical activity—consumes measurable cognitive resources, leading to fatigue when demands exceed replenishment through rest.