The present findings provide new evidence of elevated meal energy consumption by young children when served large portions of energy-dense entrées. In this study, the children's intake of a dinner entrée increased by 33% when its portion size was doubled. Similarly, energy consumed from the entrée was increased by 33% when its ED was increased by 40%. The effects of portion size and ED on children's eating were independent of one another but acted additively to promote entrée and meal energy consumption. Entrée energy intake was increased by ≈75% and total meal energy increased by almost 35% when the entrée ED and portion size were simultaneously increased. A similarly designed adult study produced comparable findings; energy intake at the meal was 56% greater when a large portion (900 g) of an energy-dense entrée (7.32 kJ/g) was served than when a smaller portion (500 g) of a less energy-dense entrée (5.23 kJ/g) was served (15
The 15% increase in total meal energy observed in the large portion conditions is consistent with previous experimental studies of children in which meal energy increased by 13–39% when the portion size of a main lunch or dinner entrée was doubled (4
). That the effects were observed even after excluding “plate cleaners” from the analyses indicates that the results were not attributable to an artificial restriction of the entrée portion size in the reference portion size conditions. Consequently, intake of the large entrée portions appeared to be excessive relative to that of the smaller portions. Limited evidence indicates that the promotion of intake by large portions may extend beyond meals to influence total daily energy intake among children. CSFII data (1994–1996, 1998) showed that the average portion size of foods consumed explained between 17% and 19% of the variance in daily energy intake among preschool-aged children (22
). Experimental research has shown a 9% increase in daily energy intake among African American and Hispanic preschoolers when the portion sizes of entrées and a snack served over a 24-h period were doubled (17
). Adult studies have also shown portion size effects on energy intake over 2- (23
) and 11-d (24
) periods, when all food and beverage portions were increased. The present results clarify implications for energy balance in children by demonstrating that large portions exerted the greatest effects on meal energy when energy-dense.
Observational studies of free-living dietary intake among young children show a positive correlation between dietary ED and daily energy intake (25
). The present findings are among the first to experimentally demonstrate that processes leading to meal termination (ie, satiation) by young children are relatively insensitive to food ED. Children neither consumed fewer grams of the entrée when its ED was increased by 40% nor ate less of other foods served at the dinner meal. As a result, entrée and meal energy intakes were greater when the more energy-dense entrées were served. Adult ratings of the entrées, obtained as part of this research, indicate that the results were not likely explained by sensory differences between the reference and high-ED versions. The observed effect of entrée ED on meal energy is congruous with the findings of a recent study of 2- to 5-y-olds using a similar ED manipulation (11
). In that study, children consumed 25% less energy at meals when served a 1.4-kcal/g entrée than when served a 2.0-kcal/g entrée. The present findings are also in general agreement with adult studies; a consistent weight (volume) of food was consumed at single and multiple meals when the ED of a given menu was systematically varied (7
for a review).
The mechanisms by which ED exerts an influence on children's energy intake remain poorly understood. In contrast with effects on satiation, experimental studies of satiety (ie, the inter-meal interval) in young children have shown that subsequent ad libitum intake is suppressed in response to increases in the ED of fixed portions of foods consumed as preloads. In that work, preschool-aged children accurately adjusted their ad libitum energy intake at a meal (12
) and across successive meals (28
) to achieve constant energy intake across conditions of varying preload ED; this sensitivity, however, appears to decrease with age (29
). After a preload, there is a greater opportunity for feedback from post-ingestive signals than in studies of meal termination during ad libitum consumption. It is possible that post-ingestive signals from food ED inhibit appetitive drive but are less tightly controlled than those processes that defend against energy deficit (30
). Additional research is needed to understand the basis of apparent differences in effects of food ED on young children's satiation and satiety.
Limited evidence suggests that overweight individuals consume larger food portions and have more energy-dense diets. Data from the CSFII, 1994–1996 and 1998, show that heavier toddlers (31
) and adolescents (32
), but not preschoolers (32
), consumed larger food portions. A relation between child weight status and dietary ED has not been established. Among adults, however, weight status has been positively associated with dietary ED, both with (33
) and without the inclusion of energy-containing beverages (34
). In the present study, interactions of child weight status with portion size and ED were not significant. Consistent with previous laboratory studies (5
), these findings indicate that the effects of portion size and ED were not moderated by child weight status. In other words, overweight and nonoverweight children appear to respond similarly to large food portions in the laboratory. As such, the observation that heavier children consume large food portions (31
) may reflect greater routine exposure to large portions foods rather than a weight-based susceptibility to overconsume them.
The use of a small convenience sample in this research limits the generalizabilty of the findings. Because preference data were obtained only for the unmodified version of the macaroni and cheese entrée, the extent to which differences in children's intake of the reference and high-ED entrées were due to preference is not possible to discern. Adult sensory ratings of the entrées, however, suggest that any such differences were minimal. A final consideration is that 25% of the sample consumed the reference entrée portions in full. In contrast with previous studies (5
), the “plate cleaners” consumed significantly greater amounts of the entrée in response to increasing portion size and ED than the rest of the children. It is not possible to discern the extent to which the intake of “plate cleaners” was restricted by the reference portions. The main findings, however, were unchanged when the data from children who consumed ≥95% of the reference portions were excluded. Future work is needed to understand how “plate cleaners” respond to increasing food portion size.
In conclusion, this study revealed independent and additive effects of entrée portion size and ED on young children's entrée intake and total energy consumed at the meal. These results support the perspective that large portions of energy-dense foods foster obesigenic eating behavior among young children by promoting energy intake at meals.