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This simple thermodynamic model intake minus expenditure leaves out (at least) one dynamic metabolic feature: this engine can change its tendency for storage (

This simple thermodynamic model intake minus expenditure leaves out (at least) one dynamic metabolic feature: this engine can change its tendency for storage (weight gain) in a single organism or in a community of organisms given time. A change in the community storage tendency is what is alluded to in the linked article. That is, the organism can allow the excess calories to pass on by, or it can store it as fat (or glycogen). This, for instance, is the holy grail of weigh managing pharmaceuticals: to discover those effectors of "now store every un-expended calorie (as fat)". So finally it's something like: intake - expenditure = available for storage, but might not be stored.

DennisP 11y ago
And the other variable is how well the body turns fat reserves back into available energy. If that mechanism is inefficient then the equilibrium will be higher body fat. People seem to have an idea that every human body can just instantly burn however much fat it needs to burn to meet demand. It seems more likely that there's a limit to how fast the body can burn fat, which for some people is unusually low, and that if there's not enough energy available you'll be forced by thermodynamics to move less, think poorly, and produce less body heat.