Relationship between portion size and energy intake among infants and toddlers: evidence of self-regulation.

OBJECTIVES: To assess whether dietary intakes of infants and young toddlers show evidence of energy self-regulation.

DESIGN: Data from 24-hour recalls collected in the 2002 Feeding Infants and Toddlers Study were analyzed. Multivariate regressions were used to explore the relationship between portion size and usual energy intake as well as the relationship between portion size, number of eating occasions, number of unique foods, and energy density.

SUBJECTS/SETTING: A national random sample of 3,022 US infants and toddlers 4 to 24 months of age.

STATISTICAL ANALYSES PERFORMED: To measure variability in portion size, an average portion size z score was computed for each child in the sample, across 45 different food groups. The number of eating occasions was defined as the total number of times a child had anything to eat or drink during the day, excluding eating occasions that included only water and/or supplements. The total number of unique foods in a day was defined as the number of unique food codes included in the 24-hour recall, and energy density was computed as kilocalories/gram, including all foods, beverages, and water. Linear regression models were used to assess the effect of portion size and other self-regulation mechanisms on energy intake and to assess the effect of these self-regulation mechanisms on portion size. Separate analyses were performed for three age groups: 4 to 5 months, 6 to 11 months, and 12 to 24 months.

RESULTS: A significant negative association was found for all age groups between the number of eating occasions and average portion size z scores, indicating that children who eat less often during the day consume larger-than-average-portion sizes and children who eat more often during the day consume smaller-than-average portions. For infants (11 months and younger), a significant negative association was noted between energy density and average portion size z scores, indicating that, as the energy density of the diet goes down, infants consume larger-than-average portions and, as the energy density of the diet goes up, they consume smaller-than-average portions. Among infants 6 to 11 months, there was a significant positive relationship between portion size and the number of unique foods consumed. For toddlers, there was no association between average portion size z scores and energy density, suggesting that energy self-regulation mechanisms are diminished in this age group.

CONCLUSIONS: Our findings confirm the presence of energy self-regulation among infants and young toddlers. These findings can be used to assure parents and caregivers that infants have an innate ability to regulate energy intake. At the same time, it is important to educate parents and caregivers about the potential for environmental cues to diminish natural hunger-driven eating behaviors, even among young toddlers. Dietetics professionals should emphasize the potential adverse effects that coercive feeding behaviors can have on children's innate ability to regulate energy intake. This includes not only admonitions to "clean your plate," but overrestriction of intake that may be motivated by concerns that children are overeating.