The effects of food characteristics on portion selection and consumption in children
Restricted (Penn State Only)
- Author:
- Diktas, Hanim Ecem
- Graduate Program:
- Nutritional Sciences
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- September 19, 2022
- Committee Members:
- Barbara Rolls, Chair & Dissertation Advisor
Jennifer Williams, Major Field Member
Kathleen Keller, Major Field Member
John Hayes, Outside Unit & Field Member
Marion M. Hetherington, Special Member
Gregory Shearer, Professor in Charge/Director of Graduate Studies - Keywords:
- Portion Size
Portion Selection
Middle childhood
preschool children
Energy intake
Food liking
Energy density - Abstract:
- Currently, one out of five children in the United States has obesity. Serving larger portion sizes and energy-dense foods has robust effects on children’s intake, and it is often suggested that these factors play a critical role in contributing to childhood obesity. Experimental studies showed that portion size has sustained and robust effects on energy intake in children, particularly when the foods are well-liked and energy-dense. These studies suggest that food characteristics such as portion size, energy density, and palatability contribute to excess energy intake. The strategic use of these characteristics may, on the other hand, promote healthy eating in children. Only a few studies, however, have examined the influences of these food characteristics on the selected portions and intake during the formative years of childhood. Therefore, the primary aim of this dissertation is to understand the effects of food characteristics on portion selection and consumption in children. Study 1 evaluated the independent and combined effects on preschool children’s vegetable intake of serving a larger portion of vegetables and enhancing their flavor. In a crossover design, lunch was served in childcare centers once a week for four weeks to 67 children aged 3–5 y (26 boys, 41 girls). The meal consisted of two familiar vegetables (broccoli and corn) served with fish sticks, rice, ketchup, applesauce, and milk. Across the four meals, we varied the portion of vegetables (60 or 120 g total weight, served as equal weights of broccoli and corn) and served them either plain or enhanced (6.6% light butter and 0.5% salt by weight). All meals were consumed ad libitum and weighed to determine intake. Doubling the portion of vegetables led to greater consumption of both broccoli and corn (both p < 0.0001) and increased meal vegetable intake by 68% (mean ± SEM 21 ± 3 g). Enhancing vegetables with butter and salt, however, did not influence their intake (p = 0.13), nor did flavor enhancement modify the effect of portion size on intake (p = 0.10). Intake of other meal components did not change when the vegetable portion was doubled (p = 0.57); thus, for the entire meal, the increase in vegetable consumption led to a 5% increase in energy intake (13 ± 5 kcal; p = 0.02). Ratings indicated that children had similar liking for the plain and enhanced versions of each vegetable (both p > 0.31). All versions of vegetables were well-liked, as indicated by ≥ 76% of the children rating them as “yummy” or “just okay”. In study 2, we used a computer survey to investigate the effect of food liking on portion selection in middle childhood and examined how children’s selections were related to measured intake at meals in which portions of all foods were varied across 4 test days. Fifty-one children aged 7–10 y completed a computer survey of 20 common foods with a range of energy density. For each food, the survey presented sliding scales with 5 images varying in portion size and children indicated their liking and the amount they would eat at a specified meal or snack. On 4 test days in a randomized crossover design, children were served a meal of 6 foods from the survey with portions of 100%, 133%, 167%, or 200% of baseline amounts. Across the 20 foods used in the survey, portion selection ratings were predicted by food liking ratings (p < 0.0001). After accounting for liking, portion selection ratings did not vary by food energy density (p = 0.50). At the meals, intake of all 6 foods increased when larger portions were served (p = 0.002). Furthermore, the selected portion of a food on the survey was positively related both to intake of that food at the 100%-portion meal (p = 0.014) and to increased intake as larger portions were served (p < 0.0001). The final study investigated the effects of offering preschool children snacks differing in energy density on the amounts they served and then consumed. In a crossover design, 52 children aged 4-6 y (44% girls; 20% overweight) ate an afternoon snack on 2 days in their childcare classrooms. Before each snack time, children self-served the amount they would like to eat of 4 snacks presented in equal volumes but differing in ED (higher-ED: pretzels, cookies; lower-ED: strawberries, carrots). Across the 2 sessions, children were given their self-served amount of either pretzels (3.9 kcal/g) or strawberries (0.3 kcal/g) and intake was measured. Later, children tasted all 4 snacks and rated liking, then viewed the same volume of each snack and rated how much it would fill their stomach. Results showed that the portions children served themselves were influenced by their liking ratings (p=0.0006), but after accounting for liking, the volumes they served were similar for all 4 foods (p=0.27). At snack time, children ate a smaller proportion of self-served pretzels (73±4%) than strawberries (92±4%; p=0.0003), but because of the ED difference they consumed 55±4 kcal more from pretzels than strawberries (p<0.0001). In contrast to self-served volume, the difference in consumed volume was not attributable to the liking ratings (p=0.87). In the fullness task, children were more likely to indicate a completely full stomach for the 2 higher-ED snacks than the 2 lower-ED snacks (p=0.0014). Collectively these three studies provided new scientific evidence around the effects of food characteristics on the selected portions and intake during the formative years of childhood. Serving a larger portion of vegetables at a meal was an effective strategy to promote vegetable intake in children. Although butter and salt were not necessary to increase consumption of well-liked vegetables, it is still likely that the effectiveness of promoting vegetable intake by serving larger portions will depend on the children’s liking for the vegetables. We also found that food liking ratings across a range of foods were a major determinant of portion selection in middle childhood. At age 7, children were able to select portions on a computer survey that predicted their measured intake in response to increased portion size, highlighting the utility of computer surveys to enhance our understanding of the determinants of the portion size effect. After accounting for food liking, energy density had no independent effect on portions that were selected on a computer survey or manually self-served. We also found that when preschool children were presented with equal volumes of snack foods, they selected portions based on visual cues, and their energy intake strongly depended on the foods' energy density. Overall, these studies indicate that while visual cues and liking influence portion selection, energy density influences energy intake during the formative years of childhood. Considered together, these food characteristics can serve as potential targets for developing effective strategies to encourage children to consume a healthy diet and moderate energy intake.