Beginning with Pavlov (1927), there has been great interest in how associative learning processes affect eating behavior. For instance, flavors can become preferred when paired with calories or, conversely, become aversive when paired with illness. This relationship between flavors and caloric or toxic outcomes has been investigated by a number of theorists. We studied the effect of daily consumption of a flavor that was either paired or unpaired with calories provided by sugar on body weight change and daily food consumption over a 21-day period. Over three experiments, we observed an unanticipated attenuation of weight gain following consumption of flavored liquid solutions, particularly when those solutions were non-caloric. However, we did not find any impact of consuming the flavored liquid solutions on appetite. Given differences in weight gain in the absence of differences in the amount of food consumed, we suggest that unconditioned metabolic responses are elicited to initially novel flavor stimuli, even if those flavors are not followed by caloric outcomes. Potential dieting interventions based on these findings are discussed as is how they inform our understanding of the balance between unconditioned and conditioned responses.
Keywords: Eating; Energy regulation; Learning; Metabolism; Pavlovian conditioning; Weight gain.