Food reinforcement and obesity. Psychological moderators.

The relative reinforcing value of food (RRV(food)) provides an index of the motivation to eat. Research has shown that RRV(food) is higher in obese individuals than their non-obese peers, is associated with greater energy intake, predicts weight gain and interacts with impulsivity to predict energy intake. This study was designed to determine whether dietary restraint, dietary disinhibition or hunger moderate the effect of RRV(food) on the weight status and energy intake in 273 adults of various body mass index (BMI) levels. Hierarchical regression was used to assess the independent effects of RRV(food) on BMI and energy intake, controlling for age, sex, income, education, minority status, and RRV(reading). Results showed that greater RRV(food), but not RRV(reading), was associated with greater BMI and energy intake. Dietary disinhibition and dietary restraint moderated the relationship between RRV(food) and BMI, with dietary disinhibition being a stronger moderator of this relationship (r(2)=0.20) than dietary restraint (r(2)=0.095). In addition, dietary disinhibition moderated the effect of RRV(food) on energy intake. These results replicate the importance of RRV(food) as a predictor of obesity, and show that psychological factors moderate the effect of food reinforcement on body weight and energy intake. This trial was registered at clinicaltrials.gov as NCT00962117.