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Although we are just beginning to understand how environmental factors such as portion size affect eating behavior, the available data suggest that large portions of energy-dense foods are contributing to the obesity epidemic. Several possible strategies for adjusting portions to bring intake back in line with energy requirements are discussed. The continuing rise in the rates of obesity calls for urgent action.
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OBJECTIVES: Because larger food portions could be contributing to the increasing prevalence of overweight and obesity, this study was designed to weigh samples of marketplace foods, identify historical changes in the sizes of those foods, and compare current portions with federal standards. METHODS: We obtained information about current portions from manufacturers or from direct weighing; we obtained information about past portions from manufacturers or contemporary publications. RESULTS: Marketplace food portions have increased in size and now exceed federal standards. Portion sizes began to grow in the 1970s, rose sharply in the 1980s, and have continued in parallel with increasing body weights. CONCLUSIONS: Because energy content increases with portion size, educational and other public health efforts to address obesity should focus on the need for people to consume smaller portions.
A review of research studies that focus on the validity of portion-size measurement aids (PSMAs) was undertaken because guidelines for the use of PSMAs in studies of food intake have not been developed. Also, the accuracy of food quantity estimates may greatly influence the quality of dietary intake data. Generally, the review indicated that differences between the food quantity estimates obtained from different PSMAs were not statistically significant. Research on PSMA accuracy was lacking in several areas. Additional information is needed on the validity of PSMAs, particularly as it relates to PSMA use by different socio-demographic groups. Little research has focused on the specific effects that PSMAs have on quantity estimates or on subject perceptions of PSMA use. Improved reporting of PSMAs in the literature is also needed. Future research should be directed toward these issues so that PSMA guidelines can be developed. Until there is a more complete research base, it is not possible at this time to establish guidelines for use of PSMAs in clinical practice or in research settings.
OBJECTIVE: Using self-refilling soup bowls, this study examined whether visual cues related to portion size can influence intake volume without altering either estimated intake or satiation. RESEARCH METHODS AND PROCEDURES: Fifty-four participants (BMI, 17.3 to 36.0 kg/m2; 18 to 46 years of age) were recruited to participate in a study involving soup. The experiment was a between-subject design with two visibility levels: 1) an accurate visual cue of a food portion (normal bowl) vs. 2) a biased visual cue (self-refilling bowl). The soup apparatus was housed in a modified restaurant-style table in which two of four bowls slowly and imperceptibly refilled as their contents were consumed. Outcomes included intake volume, intake estimation, consumption monitoring, and satiety. RESULTS: Participants who were unknowingly eating from self-refilling bowls ate more soup [14.7+/-8.4 vs. 8.5+/-6.1 oz; F(1,52)=8.99; p<0.01] than those eating from normal soup bowls. However, despite consuming 73% more, they did not believe they had consumed more, nor did they perceive themselves as more sated than those eating from normal bowls. This was unaffected by BMI. DISCUSSION: These findings are consistent with the notion that the amount of food on a plate or bowl increases intake because it influences consumption norms and expectations and it lessens one's reliance on self-monitoring. It seems that people use their eyes to count calories and not their stomachs. The importance of having salient, accurate visual cues can play an important role in the prevention of unintentional overeating.
A self-administered food use questionnaire which included 276 food items and mixed dishes and a portion size picture booklet with 122 photographs was developed for a large lung cancer intervention trial among approximately 27,000 Finnish men aged 50-69 years. The reproducibility and validity of this questionnaire were studied from March to October 1984. In the reproducibility study, 121 men aged 55-69 years completed the questionnaire three times, at three-month intervals. The intraclass correlations varied from 0.56 for vitamin A to 0.88 for alcohol, with most falling between 0.60 and 0.70. In the validity study, 190 men of similar age kept food consumption records for 12 two-day periods, distributed evenly over a period of six months, and filled in the questionnaire both before and after this period. Correlations between nutrient intake values from the food records and the food use questionnaires ranged from 0.40 for selenium to 0.80 for alcohol. Among subjects who belonged to the lowest quintile on the basis of the food record measurement, an average of 51 per cent fell into the same quintile and 76 per cent fell into the lowest two quintiles when they were categorized on the basis of the food use questionnaire. Findings were similar for the upper tail of the distribution. These data indicate that the self-administered food use questionnaire is useful for measuring individual or group intakes for a variety of nutrients.
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.
OBJECTIVE: It is often believed that people overeat the foods they like. We investigated whether environmental cues such as packaging and container size are so powerful that they can increase our intake of foods that are less palatable. DESIGN, SETTING, AND PARTICIPANTS: In a 2 x 2 between-subjects design, 158 moviegoers in Philadelphia (57.6% male; 28.7 years) were randomly given a medium (120 g) or a large (240 g) container of free popcorn that was either fresh or stale (14 days old). Following the movie, consumption measures were taken, along with measures of perceived taste. OUTCOME MEASURES AND RESULTS: Moviegoers who were given fresh popcorn ate 45.3% more popcorn when it was given to them in large containers. This container-size influence is so powerful that even when the popcorn was disliked, people still ate 33.6% more popcorn when eating from a large container than from a medium-size container. CONCLUSIONS AND IMPLICATIONS: Even when foods are not palatable, large packages and containers can lead to overeating. The silver lining of these findings may be that portion size can also be used to increase the consumption of less preferred healthful foods, such as raw vegetables.
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People seem to think that a unit of some entity (with certain constraints) is the appropriate and optimal amount. We refer to this heuristic as unit bias. We illustrate unit bias by demonstrating large effects of unit segmentation, a form of portion control, on food intake. Thus, people choose, and presumably eat, much greater weights of Tootsie Rolls and pretzels when offered a large as opposed to a small unit size (and given the option of taking as many units as they choose at no monetary cost). Additionally, they consume substantially more M&M's when the candies are offered with a large as opposed to a small spoon (again with no limits as to the number of spoonfuls to be taken). We propose that unit bias explains why small portion sizes are effective in controlling consumption; in some cases, people served small portions would simply eat additional portions if it were not for unit bias. We argue that unit bias is a general feature in human choice and discuss possible origins of this bias, including consumption norms.
OBJECTIVE: This paper compares the accuracy of visual estimations of children's food intake in settings where several children eat together off 1 plate vs individual-plate eating scenarios. DESIGN: Eight trained observers were tested in their ability to estimate food portions consumed by children enacting common eating scenarios. Foods were categorized by food group and according to their presentation by individual-plate and shared-plate. Observed food weight estimates were compared to actual weights. SUBJECTS/SETTING: The 8 observers visually estimated 69 food portions of children eating alone and 26 portions where children were eating from a shared plate. This study was carried out in Sarlahi District, a rural, central lowland region of Nepal. STATISTICAL ANALYSES: Pearson's correlation coefficients were calculated to examine associations between estimated and actual weights. A fixed effects model was constructed to compare observers. RESULTS: Analyses revealed that observer estimates of food weights under field conditions were well correlated with actual weights for individual-plate (r = 0.89) and for shared-plate (r = 0.84) scenarios. Observers estimated food weights when children ate together on a shared plate less accurately than they did in settings where children ate alone. With the exception of 1 observer, observers did not differ significantly in their ability to estimate food weights. Accuracy of estimations was influenced by food weight with greater error associated with food quantities of less than 70 g. CONCLUSIONS: Visual estimation is a relatively accurate, valid method of assessing child food intake under rural field conditions, and the only method to obtain accurate information on dietary intake in regions where shared-plate eating is frequent.
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BACKGROUND: Because people eat most of what they serve themselves, any contextual cues that lead them to over-serve should lead them to over-eat. In building on the size-contrast illusion, this research examines whether the size of a bowl or serving spoon unknowingly biases how much a person serves and eats. METHODS: The 2 x 2 between-subjects design involved 85 nutrition experts who were attending an ice cream social to celebrate the success of a colleague in 2002. They were randomly given either a smaller (17 oz) or a larger (34 oz) bowl and either a smaller (2 oz) or larger (3 oz) ice cream scoop. After serving themselves, they completed a brief survey as their ice cream was weighed. The analysis was conducted in 2003. RESULTS: Even when nutrition experts were given a larger bowl, they served themselves 31.0% more (6.25 vs 4.77 oz, F(1, 80) = 8.05, p < 0.01) without being aware of it. Their servings increased by 14.5% when they were given a larger serving spoon (5.77 vs 5.04 oz, F(1, 80)=2.70, p = 0.10). CONCLUSIONS: People could try using the size of their bowls and possibly serving spoons to help them better control how much they consume. Those interested in losing weight should use smaller bowls and spoons, while those needing to gain weight--such as the undernourished or aged--could be encouraged to use larger ones. Epidemiologic implications are discussed.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.