Food reinforcement, energy intake, and macronutrient choice

Abstract

Background: Food is a powerful reinforcer that motivates people to eat. The relative reinforcing value of food (RRV(food)) is associated with obesity and energy intake and interacts with impulsivity to predict energy intake.

Objective: How RRV(food) is related to macronutrient choice in ad libitum eating tasks in humans has not been studied; however, animal research suggests that sugar or simple carbohydrates may be a determinant of reward value in food. This study assessed which macronutrients are associated with food reinforcement.

Design: Two hundred seventy-three adults with various body mass indexes were assessed for RRV(food), the relative reinforcing value of reading, food hedonics, energy intake in an ad libitum taste test, and usual energy intake derived from repeated 24-h dietary recalls. Multiple regression was used to assess the relation between predictors of total energy and energy associated with macronutrient intake after control for age, sex, income, education, minority status, and other macronutrient intakes.

Results: The results showed that the relative proportion of responding for food compared with reading (RRV(prop)) was positively related to body mass index, laboratory-measured energy intake, and usual energy intake. In addition, RRV(prop) was a predictor of sugar intake but not of total carbohydrate, fat, or protein intake.

Conclusion: These results are consistent with basic animal research showing that sugar is related to food reward and with the hypothesis that food reward processes are more strongly related to eating than are food hedonics. This trial was registered at clinicaltrials.gov as NCT00962117.

FIGURE 1.

Mean (±SEM) sugar energy intake by participants who were stratified by their responses to receive food or reading time (P_{max food}/(P_{max food} + P_{max reading}): low preference for food (<0.2; n = 55), moderate preference for food (≥0.2 and <0.5; n = 95), or high preference for food (≥0.5; n = 123) relative to preference for reading. The relation between the relative reinforcing value of food compared with that of reading and sugar energy intake was P = 0.036 after control for age, sex, education, minority status, BMI, and energy intake from fat and protein. P_max represents the breakpoint.