Being hungry or full influences our risk taking.

Dolan's group does some neat experiments showing that having a full stomach makes us more risk aversive in monetary decisions. We act just like other animals, who often express a preference for risky (more variable) food sources when below a metabolic reference point (hungry), and safe (less variable) food sources when sated. We follow an ecological model of feeding behavior, not the behavior predicted by normative economic theory. Thus hormone levels that reflect our metabolic state (ghrelins signalling acute nutrient intake and leptins providing an assay of energy reserves) can, like oxytocin and testosterone, influence our economic choices.