Liane S. Roe

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.

Sensory-specific satiety is affected more by volume than by energy content of a liquid food

As a food is consumed, its perceived pleasantness declines compared to that of other foods. This phenomenon, referred to as sensory-specific satiety, contributes to the termination of eating, along with other factors. This study tested whether the change in ratings of pleasantness after consuming a food is related to either the amount of food that is consumed or to its energy content. On each of 3 days, 36 women consumed a different formulation of a milk-based liquid food: (1) 300 ml, 2067 kJ; (2) 600 ml, 2067 kJ; or (3) 600 ml, 4134 kJ. The three formulations of the liquid food varied in volume and energy, but were matched for palatability and macronutrient composition. Participants rated the pleasantness of samples of the liquid food and four other foods both immediately before and after consumption of the liquid food. Results showed that doubling the volume of the liquid food that was consumed, without changing the energy content, significantly decreased pleasantness ratings of the liquid food and increased sensory-specific satiety. Doubling the energy content of the food without changing its volume, however, had no additional effect on the decrease in the ratings or on sensory-specific satiety. These results suggest that the volume of food that is consumed has a greater influence on perceptions of a foods pleasantness than does its energy content. Thus, the volume of food may affect the termination of eating in part through effects on sensory-specific satiety.

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.

Effect of the volume of liquid food infused intragastrically on satiety in women

This experiment examined whether food volume and energy content affected satiety in lean and obese women, when visual and oral cues were bypassed by infusing food intragastrically. The effects of volume and energy content were examined separately by using liquid foods that differed in energy density (kcal/g). On 5 separate days, 25 lean and 29 obese women consumed all of their meals in the laboratory. A nasogastric tube was inserted 30 min before lunch on 4 days; on three of these occasions, a liquid preload was infused for 15 min and, on the fourth occasion (control), the preload was diverted covertly. On the remaining day, no tube was inserted. The three preloads varied two-fold in volume and energy content: 200 ml/200 kcal, 400 ml/200 kcal and 400 ml/400 kcal. The results showed that increasing the volume of infused food, but not the energy content, affected satiety in both lean and obese women. There was a mean decrease in energy intake at lunch of 77 kcal (13%) after the 400-ml preload compared with the iso-energetic 200-ml preload (P=.013). Increasing the energy content of infused food, but not the volume, did not affect satiety. Thus, when sensory cues were bypassed, the volume of liquid food infused intragastrically affected subsequent energy intake in both lean and obese women. These results suggest that gastric and postgastric mechanisms are involved in the effects of high-volume, low-energy-dense foods on satiety.

Eating vegetables first: the use of portion size to increase vegetable intake in preschool children

BACKGROUND Serving larger portions of low-energy-dense vegetables at a meal could have beneficial effects on childrens food and energy intakes. OBJECTIVE We investigated whether increasing the portion size of vegetables served at the start of a meal leads to increased vegetable consumption and decreased meal energy intake in children. DESIGN In a crossover design, 3- to 5-y-old children in a daycare center were served a test lunch once a week for 4 wk (n = 51). In 3 of the meals, a first course of raw carrots varied in portion size (30, 60, or 90 g), and no first course was served in the control meal. Children consumed the first course ad libitum over 10 min and then were served a main course of pasta, broccoli, applesauce, and milk, which was also consumed ad libitum. RESULTS Total vegetable consumption at the meal increased as the portion size of carrots increased (P < 0.0001). Doubling the portion size of the first course increased carrot consumption by 47%, or 12 +/- 2 g (P < 0.0001). Tripling the portion size of carrots, however, did not lead to a further increase in intake (P = 0.61). Meal energy intake was not significantly affected by the amount of carrots served in the first course. The effect of portion size on intake was not significantly influenced by the childrens age or body weight status. CONCLUSION Increasing the portion size of a vegetable served as a first course can be an effective strategy for increasing vegetable consumption in preschool children.

Does nutrition information about the energy density of meals affect food intake in normal-weight women?

This study investigated whether the energy density of foods affected energy intake when subjects were informed about the energy density of their meals. Forty normal-weight women ate breakfast, lunch, and dinner in the laboratory on three separate days. The entrée at each meal was varied in energy density to be either 1.25, 1.50, or 1.75 kcal/g (5.23, 6.28, or 7.32 kJ/g), but was held similar in macronutrient composition and palatability. On each day, the entrées at all three meals had the same energy density. All entrées were consumed ad libitum. Subjects were assigned to one of two groups. Subjects in the information group received a nutrition label with each meal, which showed the energy density of the entrée. Subjects in the no-information group did not receive any nutrition information. The results revealed that subjects in both groups had the same pattern of food intake across the three levels of energy density. Energy density significantly affected energy intake; subjects in both groups combined consumed 22% less energy in the condition of low energy density than in the condition of high energy density (p < 0.0001). These findings show that energy density can have a significant influence on energy intake, even when individuals are informed about the energy density of their meals.

Effects of Doubling the Portion Size of Fruit and Vegetable Side Dishes on Children's Intake at a Meal

Increasing the portion size of energy‐dense entrées has been shown to increase childrens energy intake during a meal. It remains to be investigated whether serving larger portions to children can be used to promote intake of more healthful foods, such as fruits and vegetables (F&V). The aim of the present study was to examine the effects of increasing the portion size of F&V side dishes on childrens intake. Forty‐three children (22 boys, 21 girls), aged 5–6 years, were served dinner once a week for 2 weeks. Each dinner consisted of pasta with tomato sauce, three F&V side dishes (broccoli, carrots, and applesauce), and milk. The portion size of the F&V was doubled between experimental conditions whereas the size of the pasta remained constant. Doubling the portion size of the side dishes resulted in a 43% increase in childrens intake of the fruit side dish (P = 0.001), but did not affect childrens intake of the two vegetable side dishes (P > 0.60). Further, when the portion size of F&V side dishes was doubled, children ate significantly less of the pasta (P = 0.04). The difference in meal energy intake between portion size conditions (19.5 ± 16.3 kcal) was not significant (P = 0.24). Although more studies are needed to understand whether increases in portion size can influence vegetable intake, children did eat more in response to a large quantity of a preferred low energy‐dense fruit side dish at meals. Thus variations in portion size can be used strategically to help children achieve the recommended intake of fruits.

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.

Hiding vegetables to reduce energy density: an effective strategy to increase children's vegetable intake and reduce energy intake

BACKGROUND Strategies are needed to increase childrens intake of a variety of vegetables, including vegetables that are not well liked. OBJECTIVE We investigated whether incorporating puréed vegetables into entrées to reduce the energy density (ED; in kcal/g) affected vegetable and energy intake over 1 d in preschool children. DESIGN In this crossover study, 3- to 5-y-old children (n = 40) were served all meals and snacks 1 d/wk for 3 wk. Across conditions, entrées at breakfast, lunch, dinner, and evening snack were reduced in ED by increasing the proportion of puréed vegetables. The conditions were 100% ED (standard), 85% ED (tripled vegetable content), and 75% ED (quadrupled vegetable content). Entrées were served with unmanipulated side dishes and snacks, and children were instructed to eat as much as they liked. RESULTS The daily vegetable intake increased significantly by 52 g (50%) in the 85% ED condition and by 73 g (73%) in the 75% ED condition compared with that in the standard condition (both P < 0.0001). The consumption of more vegetables in entrées did not affect the consumption of the vegetable side dishes. Children ate similar weights of food across conditions; thus, the daily energy intake decreased by 142 kcal (12%) from the 100% to 75% ED conditions (P < 0.05). Children rated their liking of manipulated foods similarly across ED amounts. CONCLUSION The incorporation of substantial amounts of puréed vegetables to reduce the ED of foods is an effective strategy to increase the daily vegetable intake and decrease the energy intake in young children. This trial was registered at clinicaltrials.gov as NCT01252433.