Although evidence exists that young children have the ability to regulate energy intake within meals (9
) and over the course of the day (20
), children’s ability to self-regulate energy intake is continually subject to modification by factors within the environment in which eating occurs (22
). The findings of this research indicate that large portions may constitute an obesigenic influence on young children’s eating by promoting intake at meals. In the present study, doubling the size of the entrée increased entrée and total energy intakes at lunch 25% and 15%, respectively. The finding that the children’s intake was not limited by the total energy provided at the reference-portion lunches indicates that the children’s intake at the large-portion lunches was in excess of normal consumption.
An effect of large portions on intake at meals is consistent with the results observed among older preschool-aged children in the study by Rolls et al (8
), as well as with the results of a few studies in adults (23
). In particular, doubling the portion size of a dinner entrée increased entrée intake among adults by 30% (26
). The results of the present study extend the results of previous research with preschool-aged children (8
) by showing that increases in children’s intakes are both immediate and consistent over time with repeated exposure to large portions. Furthermore, the findings of the present study indicate that elevations in intake are attributable to increases in the average size of children’s bites of an entrée without compensatory decreases in the intake of other foods at the meal. Additional studies are needed to determine the extent to which portion size–related increases in young children’s intake at individual meals are sustained across subsequent meals and have the potential to promote positive energy balance.
In the present study, few children made comments about portion size, and the children’s self-selected portions of the entrée did not change with repeated exposure to large portions. It is possible that changes in portion size may have been visually difficult to discern because of the use of an amorphous entrée (27
). In any case, these findings indicate that increases in children’s entrée bite size and intake occurred without appreciable awareness of changes in portion size. A recent survey by the American Institute for Cancer Research (28
) found that less than one-third of 1003 adults surveyed believe that portion sizes at restaurants have increased over the past 30 y. Furthermore, adults tend to view the portion size they typically consume as being a “medium” portion, regardless of its actual size (29
). The visual-cognitive mechanisms through which large portions stimulate intake have not been identified. It is possible that naive visual cues regarding the amount of food on the plate provide a subtle anchor for determining how much food is brought to the mouth at any time. This perspective is consistent with the results of a study in adults that showed that the selected portion size of various foods increased with the size of the box in which those foods were contained (30
Although unchanged by exposure to large portions in the present study, the children’s own self-selected portions were closely tied to their entrée intake and were consistently smaller than those served to them at the large-portion lunches. Furthermore, the children consumed ≈25% more of the entrée when the large portion was presented on their plates than they did when the large portion was presented in a serving bowl from which they could self-select their own portion. These findings indicate that self-served portions may play an important role in circumventing children’s exposure to excessive portion sizes and the consequent effects on intake. Morris et al (26
) found no effects of serving method on the amount of a dinner entrée consumed by adults. How young children establish typical or customary self-served portion sizes is unknown. In a recent survey of adults, 40% failed to report that hunger was an important factor in determining their portion size, and between one-quarter and one-third of those surveyed reported that habitual portions and the amount served to them were influential factors (28
). Research is needed to understand the factors that shape children’s habitual portions, such as whether food is typically served by the parent or the child.
The findings of the present study provide evidence that the intake-enhancing effects of exposure to large portions are apparent by 3 y of age. In contrast with the results of the study by Rolls et al (8
), portion size effects on entrée intake were observed for both the younger and the older preschool-aged children in the present study. Consistent with the results of previous research, however, the older children showed larger increases in total energy intake at lunch than did the younger children, suggesting that the effects on total energy intake at meals are more pronounced as children transition through the preschool period. Furthermore, because several of the age effects were of borderline significance, it is possible that other age effects were present but not detected. Although the sample sizes were similar across studies, the portion size manipulation used in the present study was smaller than that used by Rolls et al (8
). Equally plausible and perhaps more important is the possibility that the magnitude of developmental differences in children’s responsiveness to portion size may become more pronounced with increasing age and exposure to environmental influence. Because the average age of the younger and the older preschool children in the present study differed by < 1 y, additional research is needed to evaluate developmental differences in children’s responses to large portions.
The results of the present study provide preliminary evidence that individual differences in children’s susceptibility to large portions may reflect a general insensitivity to fullness cues. In this study, greater increases in entrée intake and a nonsignificant trend for greater increases in total energy intake at lunch occurred among the children who had greater intakes in the absence of hunger. This finding indicates that children who exhibit weak satiety responses by eating in the absence of hunger may also have insufficient satiation cues or the behavioral inclination to ignore those cues when exposed to large portions. The implications of these individual differences for overweight among children, however, are unclear; responsiveness to large portions was not associated with children’s weight status. Observational studies, however, showed that girls who eat greater amounts when exposed to large portions of energy-dense foods in the absence of hunger tend to be heavier (10
). Similarly, overweight adults ate more when presented with 3 sandwiches than when presented with 1, whereas normal-weight adults ate the same amount in both cases (31
). Larger samples are needed to confirm these results and to adequately evaluate the extent to which individual differences in susceptibility to portion size confer an increased risk of overweight.
In conclusion, the present study shows that repeated exposure to a large portion size results in consistent increases in preschool-aged children’s bite size and entrée intake at a meal. These changes occurred without observable awareness of increasing portion size or compensatory decreases in the intake of other foods at the meal. The observation that the children who ate more when served large portions also tended to have greater intakes in the absence of hunger suggests that children who show poor satiety responses may also have a greater behavioral susceptibility to this environmental cue than do other children. Finally, these data provide initial evidence that allowing children to self-select portion sizes can affect the amount consumed and may play an important role in reducing the effects of exposure to large portion sizes on children’s intake. Previous studies showed that restrictive child-feeding strategies are associated with overeating and overweight in young children (10
). At the other end of the continuum, however, the risk of overweight has been associated with neglectful family environments during childhood (32
) and with a lack of maternal knowledge of their children’s consumption of sweets (33
). Whether offering children large portion sizes is indicative of a broader and more problematic approach to child feeding is unknown and is beyond the scope of the current investigation. At a minimum, however, these results suggest that portion size has effects on children’s energy intake that could promote childhood overweight; parental monitoring is important to avoid routine exposure to large portions that far exceed children’s energy needs. Suggested intervention strategies include providing parents with information on appropriate serving sizes for children and with guidance regarding feeding practices that support adequate self-regulation of intake by children, including teaching children to choose appropriate portions in the context of excessive serving sizes.