Microeconomics of metabolism: Overflow metabolism as Giffen behaviour

Biological systems such as intracellular metabolism are rationally regulated to maximize the cellular growth rate through evolution (1-4), whereas microeconomics investigates the behaviour of consumers assumed to rationally maximize their utility (5, 6). Despite this analogy as optimization problems, the link between biology and economics has not been fully established (7, 8). Here, we developed an exact mapping between the regulation of metabolism and the theory of consumer choice, thereby revealing the correspondence between long-standing mysteries in both fields: overflow metabolism and Giffen behaviour. Overflow metabolism, particularly known as the Warburg effect in cancer (9, 10), is a seemingly wasteful but ubiquitous strategy where cells utilize aerobic glycolysis instead of the more energetically-efficient oxidative phosphorylation (9-16), whereas Giffen behaviour is the unexpected consumer behaviour where a good is demanded more as its price rises (17, 18). We revealed that the general conditions for these phenomena are trade-off and complementarity, i.e., impossibility of substitution for different goods. This correspondence implies that oxidative phosphorylation is counterintuitively stimulated when its efficiency is decreased by metabolic perturbations like drug administration. Therefore, Giffen behaviour bridges the Warburg effect and the reverse and inverse Warburg effect (19-22). This highlights that application of microeconomics to metabolism can offer new predictions and paradigms for both biology and economics.