Δ E_reserves<0

Stored compounds or structural biomass are mobilized.

Operational definition

Metabolic state.

A state in which current assimilated input is insufficient for current expenditure and the system obtains net resources by breaking down stored or functional material.

Operationally:

or, after reserves are depleted, structural biomass declines.

Catabolism occurs continuously in normal metabolism, but this category refers to a net organismal or pool-level deficit.