4 Energy Regulation System · 4.1 Primary Energy Substrate
4.1 Primary Energy Substrate
Human Fat-Based Metabolism
This page is structured as definition, control variables, causal chain, observable outputs, and boundary, and serves as a canonical definition node in Human FBM.
Primary energy substrate means the substrate class carrying dominant direct energy duty in long-term operation.
In Human FBM, the target transition is from repeated carbohydrate scheduling toward fatty-acid dominance.
Exogenous carbohydrate load determines whether carbohydrate scheduling remains dominant.
Insulin occupancy determines access to fatty-acid mobilization.
Energy sufficiency and lean-mass stability determine transition sustainability.
With lower carbohydrate input, occupancy drops and fatty-acid direct-energy share can rise.
When this share remains stable, long-term substrate dominance transition is established.
Meal-to-meal continuity improves and hunger/post-meal volatility decreases.
Body-fat allocation rhythm and execution consistency become more stable.
Short-term glucose usage does not invalidate long-term fatty-acid dominant structure.
Single-output events cannot alone confirm completed substrate transition.