Evolution in Energy-Limited States: A Stoichiometric Model of Lipid Mobilization

A theoretical model of mitochondrial β-oxidation efficiency is presented, quantifying ATP yield per oxygen atom consumed as a proxy for bioenergetic performance under oxygen-limited conditions. This P:Oβ-ox ratio, derived as a function of carbon chain length and double bonds (degree of unsaturation), reveals a family of hyperbolic surfaces with maxima that closely match the natural abundance of fatty acid (FA) species in white adipose tissue. Notably, the model predicts a crossover point at d ≈ 1.6, where breakdown efficiency becomes largely independent of chain length—coinciding with the biochemical 'sweet spot' of monounsaturated FAs commonly synthesized and mobilized in mammalian systems. The predictions align well with empirical mobilization profiles reported earlier, suggesting that evolutionary lipid design is guided by a balance between storage utility and maximal respiratory efficiency under oxygen-limited conditions. The model also points to a possible regulatory axis sensitive to oxygen and ATP, with implications for lipidomic patterning in hypoxic and energy-stressed states.