Inhibiting food reward: delay discounting, food reward sensitivity, and palatable food intake in overweight and obese women

Abstract

Overeating is believed to result when the appetitive motivation to consume palatable food exceeds an individual's capacity for inhibitory control of eating. This hypothesis was supported in recent studies involving predominantly normal weight women, but has not been tested in obese populations. The current study tested the interaction between food reward sensitivity and inhibitory control in predicting palatable food intake among energy-replete overweight and obese women (N = 62). Sensitivity to palatable food reward was measured with the Power of Food Scale. Inhibitory control was assessed with a computerized choice task that captures the tendency to discount large delayed rewards relative to smaller immediate rewards. Participants completed an eating in the absence of hunger protocol in which homeostatic energy needs were eliminated with a bland preload of plain oatmeal, followed by a bogus laboratory taste test of palatable and bland snacks. The interaction between food reward sensitivity and inhibitory control was a significant predictor of palatable food intake in regression analyses controlling for BMI and the amount of preload consumed. Probing this interaction indicated that higher food reward sensitivity predicted greater palatable food intake at low levels of inhibitory control, but was not associated with intake at high levels of inhibitory control. As expected, no associations were found in a similar regression analysis predicting intake of bland foods. Findings support a neurobehavioral model of eating behavior in which sensitivity to palatable food reward drives overeating only when accompanied by insufficient inhibitory control. Strengthening inhibitory control could enhance weight management programs.

Figure 1

Hyperbolic delay discounting function fit to the mean indifference points in the current sample. Bars represent standard errors of the means. This figure is shown for descriptive purposes only. All analyses utilized area under the curve (AUC_DD) as a measure of delay discounting.

Figure 2

Interaction between food reward sensitivity and inhibitory control. Predicted values for palatable food intake are plotted against food reward sensitivity at one standard deviation above and below the mean of AUC_DD. Lower AUC_DD reflects greater discounting of delayed rewards and lower inhibitory control. Food reward sensitivity was measured with the Power of Food Scale.