Role of child weight status and the relative reinforcing value of food in children's response to portion size increases.

Abstract

Food portion size is an important determinant of intake in children. It remains unknown if children's weight status and relative reinforcing value of food (RRVF) interact with portion size to affect intake. In a randomized crossover design, 25 normal-weight and 25 obese children, ages 8-10 years, consumed dinner once a week for 3 weeks. At each dinner, the same meal was served, but the portion size of all foods (chicken nuggets, hash browns, ketchup, green beans, brownies) and a sugar-sweetened beverage (fruit punch) varied across conditions (100, 150, and 200%). Children's RRVF was assessed using a behavioral choice task. There was a significant main effect of portion size condition (P = 0.003) and weight status (P = 0.0005) and a nonsignificant trend for a portion size-by-weight status interaction (P = 0.108) on intake. Mean intakes across conditions (100, 150, and 200%) were 801 ± 57, 964 ± 58, and 873 ± 57 kcal for normal-weight children and 1041 ± 57, 1129 ± 57, and 1210 ± 57 kcal for obese children, respectively. Neither the main effect of RRVF status nor the condition-by-RRVF status interaction was significant (P > 0.48). Environments that offer large portions of palatable foods affect all children's intake irrespective of their weight status or how reinforcing they find food to be.