Effects of daily snack food intake on food reinforcement depend on body mass index and energy density

Background: The reinforcing value of food plays a role in food consumption. We have shown previously that daily intake of a high-energy-density (HED) snack food decreases food reinforcement and food liking in nonobese women but increases food reinforcement and decreases food liking in obese women. Objective: These previous studies were conducted with the use of only HED snack foods. The purpose of this study was to determine whether these effects generalize to low-energy-density (LED) foods. Design: Participants (n = 53) had food reinforcement and food liking tested at baseline and then again after 2 wk of daily consumption of 60-g portions of an HED (n = 26) or an LED (n = 27) snack food. Results: We observed a decrease in food reinforcement in women with a lower body mass index (BMI) and an increase in food reinforcement in women with a higher BMI after 14 d of consumption of an HED snack food. Food liking decreased in all women, regardless of BMI, after repeated consumption of HED foods. Conversely, all women, regardless of BMI, showed a decrease in food reinforcement after 14 d of LED snack food consumption. Women with a lower BMI who consumed LED snacks also showed a decrease in liking, but women with a higher BMI who consumed LED foods reported no change in liking. Conclusions: These findings suggest that changes in food reinforcement after daily snack food intake are influenced by both BMI and the energy density of the foods. In addition, changes in food reinforcement cannot be explained by changes in food liking. Am J Clin Nutr 2010;91:300-8.