Jennifer S. Meengs

Increasing the portion size of a packaged snack increases energy intake in men and women

The objective of this study was to determine how the portion size of a packaged snack affects energy intake of the snack and of the subsequent meal. On five separate days, 60 subjects (34 women and 26 men) ate an afternoon snack and dinner in individual cubicles. For each snack, subjects were served one of five packages of potato chips (28, 42, 85, 128, or 170 g), which they consumed ad libitum directly from the unlabelled, opaque package. Subjects returned to the lab three hours later for a standard dinner, which was also consumed ad libitum. Results showed that snack intake increased significantly as the package size increased for both males and females (p < 0.001). The combined energy intake from snack and dinner also increased as the package size increased. On average, when served the largest snack package compared to the smallest, subjects consumed an additional 596 kJ (143 kcal) at snack and dinner combined. Results from this study demonstrate that short-term energy intake increases with increasing package size of a snack. These data suggest that the availability of large packages of energy-dense snacks may be one of the environmental influences associated with excess energy intake.

The Effect of Large Portion Sizes on Energy Intake Is Sustained for 11 Days

Objective: A previous study showed that increasing the portion sizes of all foods led to an increase in energy intake that was sustained over 2 days. The objective of the present study was to determine whether participants would compensate for excess energy intake or continue to overeat when portion sizes were increased for 11 days.

Using a smaller plate did not reduce energy intake at meals

In three cross-over experiments, we examined the effect on energy intake of changing the size of the plate used at a meal. On separate days, adults were served the same lunch menu but were given a different-sized plate. In the first study, 45 participants used each of three plate sizes (17, 22, or 26 cm) and served the main course from a large dish. In the second study, 30 participants received an equal amount of food presented on each of the two larger plates. In the third study, 44 participants used each of the three plates and selected from a buffet of five foods matched for energy density. Results showed that plate size had no significant effect on energy intake. The mean differences in intake using the smallest and largest plates in the three studies were 21+/-13 g, 11+/-13 g, and 4+/-18 g, respectively, equivalent to <142 kJ (34 kcal) and not significantly different from zero. Participants in the third study made significantly more trips to the buffet when they were given the smallest plate. These findings show that using a smaller plate did not lead to a reduction in food intake at meals eaten in the laboratory.

Portion size can be used strategically to increase vegetable consumption in adults

BACKGROUND An increase in the proportion of vegetables at meals could help achieve recommended vegetable intakes and facilitate weight management. OBJECTIVE We investigated the effects on food and energy intakes of varying the portion size and energy density of a vegetable that was added to a meal or substituted for other foods. DESIGN In 2 experiments with crossover designs, men and women were served a meal of a vegetable, grain, and meat. Across the meals, the vegetable was served in 3 portion sizes (180, 270, or 360 g) and 2 energy densities (0.8 or 0.4 kcal/g) by altering the type and amount of added fat. In the addition study (n = 49), as the vegetable portion was increased, amounts of the grain and meat were unchanged, whereas in the substitution study (n = 48), amounts of the grain and meat decreased equally. RESULTS An increase in the vegetable portion size resulted in greater vegetable consumption in both studies (mean +/- SE: 60 +/- 5 g; P < 0.0001). The addition of more of the vegetable did not significantly affect meal energy intake, whereas substitution of the vegetable for the grain and meat decreased meal energy intake (40 +/- 10 kcal; P < 0.0001). A reduction in vegetable energy density decreased meal energy intake independent of portion size (55 +/- 9 kcal; P < 0.0001). By combining substitution with a reduction in energy density, meal energy intake decreased by 14 +/- 3%. CONCLUSIONS Serving more vegetables, either by adding more or substituting them for other foods, is an effective strategy to increase vegetable intake at a meal. However, to moderate meal energy intake, vegetables should be low in energy density; furthermore, the substitution of vegetables for more energy-dense foods is more effective than simply adding extra vegetables.

Serving a variety of vegetables and fruit as a snack increased intake in preschool children

BACKGROUND Although serving a greater variety of food increases intake, this effect has not been well studied as a strategy to encourage consumption of vegetables and fruit in preschool children. OBJECTIVE This study examined whether providing a variety of familiar vegetables or fruit to preschool children as a snack would lead to increased selection and intake. DESIGN In a crossover design, 61 children (aged 3-5 y) ate a snack in their childcare facility on 8 afternoons. At 4 snack times, the children were offered vegetables: either a single type (cucumber, sweet pepper, or tomato) or a variety of all 3 types. At 4 other snack times, the children were offered fruit (apple, peach, pineapple, or all 3 types). Uniform-sized pieces were served family style, and children selected and ate as much as they desired. RESULTS Offering a variety of vegetables or fruit increased the likelihood of selection (P < 0.0001); children chose some pieces in 94% of snacks with variety and in 70% of snacks without variety. Serving a variety also increased consumption of both vegetables and fruit (P < 0.0002); the mean (±SEM) increase was 31 ± 5 g, about one-sixth the recommended daily amount. Independent of the variety effect, children were less likely to select vegetables than fruit (P < 0.0001), and the mean intake was substantially less for vegetables than for fruit (22 ± 1 compared with 84 ± 3 g). CONCLUSIONS Providing a variety of vegetables and fruit as a snack led to increased consumption of both food types in a childcare facility. Serving a variety of vegetables or fruit as a snack could help preschool children meet recommended intakes. This trial was registered at clinicaltrials.gov as NCT01557218.

Vegetable Variety: An Effective Strategy to Increase Vegetable Intake in Adults

Effective strategies are needed to increase vegetable intake in accordance with health recommendations. Previous research has shown that increasing the variety of foods leads to increased consumption, yet this strategy has not been investigated for promoting vegetable intake. This crossover study, conducted in 2008 and 2009, tested whether filling half the plate with a variety of vegetables influences vegetable consumption and meal energy intake. Once a week for 4 weeks, a meal of pasta and cooked vegetables was consumed ad libitum by 66 adults (34 women, 32 men). The meals were varied in the type of vegetables offered: at three meals 600 g of a single vegetable was served (broccoli, carrots, or snap peas) and at one meal 200 g of each of the three vegetables was served side by side. Data were analyzed using a mixed linear model with repeated measures. In this study, serving a variety of vegetables increased vegetable intake at the meal (P<0.0001). Subjects ate more vegetables when served the variety than when served any single type; the mean increase was 48±6 g, or more than one-half serving. This increase remained significant when intake of the variety of vegetables was compared with the preferred vegetable of each participant (mean 25±8 g; P=0.002). Vegetable intake was not significantly related to energy intake at the meal. The results of this study demonstrate that increasing the variety of low-energy-dense vegetables served at a meal can be used as a strategy to increase vegetable intake.

Salad and satiety: the effect of timing of salad consumption on meal energy intake

In a previous study, consuming a fixed amount of low-energy-dense salad as a first course reduced meal energy intake. We investigated whether this effect depended on serving salad before rather than with the main course, or on compulsory rather than ad libitum consumption. On five occasions, 46 women consumed ad libitum a main course of pasta, accompanied four times by low-energy-dense salad (300 g; 100 kcal [418 kJ]). At two meals the salad was served 20 min before the pasta (once compulsory; once ad libitum), and at two meals the salad was served with the pasta (once compulsory; once ad libitum). Results showed that adding a fixed amount of salad to the meal reduced energy intake by 11% (57±19 kcal [238±79 kJ]). Ad libitum salad consumption was less than compulsory consumption and did not significantly affect energy intake. Across all participants, the timing of serving the salad did not significantly influence energy intake, but the effect of timing depended on participant scores for flexible dietary restraint. Consuming low-energy-dense salad before rather than with the main course increased vegetable consumption by 23%. To moderate energy intake, maximizing the amount of salad eaten may be more important than the timing of consumption.

Variations in cereal volume affect the amount selected and eaten for breakfast.

Food volume could influence both the portions that people take and the amount that they eat, but these effects have had little investigation. The influence of food volume was tested by systematically reducing the flake size of a breakfast cereal so that the cereal was more compact and the same weight filled a smaller volume. In a crossover design, 41 adults ate cereal for breakfast once a week for 4 weeks during 2011 and 2012. The cereal was either standard wheat flakes or the same cereal crushed to reduce the volume to 80%, 60%, or 40% of the standard. A constant weight of cereal was provided in an opaque container and participants poured the amount they wanted into a bowl, added fat-free milk and noncalorie sweetener as desired, and consumed as much as they wanted. Results from a mixed linear model showed that as flake size was reduced, subjects poured a smaller volume of cereal, but still took a greater amount by weight and energy content (both P values <0.0001). Despite these differences, subjects estimated that they had taken a similar number of calories of all versions of the cereal. They ate most of the cereal they took, so as flake size was reduced, breakfast energy intake increased from a mean±standard error of the mean of 286±18 kcal to 358±19 kcal, an increase of a mean±standard error of the mean 34%±7% (P<0.0001). These findings demonstrate that variations in food volume associated with the size of a foods individual pieces affect the portion served, which in turn affects energy intake.