The purpose of this research is to determine if loss aversion is replicable as an overt behavioral response to potential gains and losses in complex, recurring, uncertain, and risky choice with real gains and losses of money and food. Cognitive methods used to determine the effect of loss have primarily measured verbal response to hypothetical choice scenarios in which participants cognitively predict their behavior in a series of bets or situations involving imagined monetary gains and losses. Less has been done using behavioral methods that measure overt behavioral response to gains and losses of actual commodities. The present study uses the experimental analysis of behavior to measure the asymmetrical effect of loss in multiple choice domains. A series of four experiments investigated four factors likely to affect the expression and degree of loss aversion: (a) learning and experience with consequences of choice; (b) real gains and losses instead of hypothetical quantities or imagined commodities; (c) gains and losses of a non-quantitative, primary reinforcer (food); and (d) the menstrual cycle. Participants played one of two computer games in which they earned or lost coins or food tokens exchanged for real food. Participants (N = 27, 15 women) played several 18-minute sessions in gains-only conditions and 16 sessions in 36-minute gains+punishment conditions. Recurring, complex, uncertain, and risky choice was simulated in the games by using 6-ply interdependent concurrent variable interval schedules of reinforcement (gains) and punishment (losses). Choice behavior with real gains and losses of money and food was modeled using the generalized matching law, allowing for the quantification of the effects of potential loss, relative to gains, as a change in bias and sensitivity. Loss aversion was operationalized as gain-loss asymmetry ratios derived from bias estimates produced in unpunished and punished choice conditions. Gain-loss asymmetry was replicated in both women and men in complex, recurring, uncertain, and risky choice with potential gains and losses of real money and food. Average gain-loss asymmetry ratios were 3 to 6 times greater in choice with money and 4 to 16 times greater in choice with food than those reported in the cognitive and behavioral literature. Although individual differences in response to loss were striking, the asymmetrically larger behavioral effects of loss, relative to gains, were nearly ubiquitous. Marked disruption in sensitivity to reinforcement was observed in punished choice for most participants, but for 33% of participants in choice with money and 42% in choice with food, sensitivity to reinforcers increased. No evidence was found for behavioral choice varying with the menstrual cycle.