On the overconsumption of food portions : is the problem in the size or the number?

While larger food portions lead to greater consumption, the effect appears to be greater when the larger food portions are created by increasing the size of food units than when created by increasing the number of food units making up the portion. Study 1 shows consumer estimates of food quantities are more sensitive to unit-number information (i.e., the number of units) and less sensitive to unit-size information (i.e., the size of food units). Estimates of the food quantity presented in a portion size are larger when the portion is presented as many, smaller units than when presented as few, larger units. Study 2 demonstrates that participants tend to consume less when a portion is presented as more, smaller units vs. few, larger units. This result along with that of Study 1 suggest the portion-size effect on consumption is inversely related to the portion-size effect on quantity perceptions. When consumers are induced to focus on unit-size rather than unit-number (Study 3), quantity estimates can be made more sensitive to unit-size manipulations. Study 4 extends this finding to show that the portion-size effect on consumption is greatest when quantity estimation is insensitive to portion size change, and mitigated when information focus encourages processing of the relevant information

Whether Smaller Plates Reduce Consumption Depends on Who's Serving and Who's Looking: A Meta-Analysis

The literature on whether varying plate size has an effect on consumption is mixed and contradictory.This meta-analysis of 56 studies from 20 papers shows that varying the size of the container holding food (e.g., plate orbowl) has a substantial effect on amount self-served and/or consumed (Cohen’s d 5 .43). More generally, we found adoubling of plate size increased the amount self-served or amount consumed by 41%. Our analysis resolves the variouscontradictions of past reviews: we found that the plate-size effect had a substantial effect on amount self-served (d 5.51) and on amount consumed when the portion was self-served (d 5 .70) or manipulated along with (confoundedwith) plate size (d 5 48). However, plate size had no effect on amount consumed when the portion size was held constant(d 5 .03). Overall, plate size had a stronger effect when participants were unaware that they were participatingin a food study (d 5 .76)

Reducing the standard serving size of alcoholic beverages prompts reductions in alcohol consumption.

AIMS: To test whether reducing the standard serving size of alcoholic beverages would reduce voluntary alcohol consumption in a laboratory (study 1) and a real-world drinking environment (study 2). Additionally, we modelled the potential public health benefit of reducing the standard serving size of on-trade alcoholic beverages in the United Kingdom. DESIGN: Studies 1 and 2 were cluster-randomized experiments. In the additional study, we used the Sheffield Alcohol Policy Model to estimate the number of deaths and hospital admissions that would be averted per year in the United Kingdom if a policy that reduces alcohol serving sizes in the on-trade was introduced. SETTING: A semi-naturalistic laboratory (study 1), a bar in Liverpool, UK (study 2). PARTICIPANTS: Students and university staff members (study 1: n = 114, mean age = 24.8 years, 74.6% female), residents from local community (study 2: n = 164, mean age = 34.9 years, 57.3% female). INTERVENTIONS AND COMPARATORS: In study 1, participants were assigned randomly to receive standard or reduced serving sizes (by 25%) of alcohol during a laboratory drinking session. In study 2, customers at a bar were served alcohol in either standard or reduced serving sizes (by 28.6-33.3%). MEASUREMENTS: Outcome measures were units of alcohol consumed within 1 hour (study 1) and up to 3 hours (study 2). Serving size condition was the primary predictor. FINDINGS: In study 1, a 25% reduction in alcohol serving size led to a 20.7-22.3% reduction in alcohol consumption. In study 2, a 28.6-33.3% reduction in alcohol serving size led to a 32.4-39.6% reduction in alcohol consumption. Modelling results indicated that decreasing the serving size of on-trade alcoholic beverages by 25% could reduce the number of alcohol-related hospital admissions and deaths per year in the United Kingdom by 4.4-10.5% and 5.6-13.2%, respectively. CONCLUSIONS: Reducing the serving size of alcoholic beverages in the United Kingdom appears to lead to a reduction in alcohol consumption within a single drinking occasion

The portion size effect and overconsumption – towards downsizing solutions for children and adolescents

Portion sizes of foods offered to consumers have increased at the same time as overweight and obesity levels have risen. It has been suggested that large portions of high energy density (HED) foods increase total energy intake and that this is not compensated for in the short- to medium-term, potentially promoting weight gain. In the laboratory setting, offering large portions of HED foods increases overall energy intake in both children and adults. This phenomenon is known as the portion size effect (PSE), and it is robust, reliable and enduring. The possible impact of the PSE is that large portions served over time may facilitate overeating and could contribute to overweight and obesity. Explanations for the PSE vary from simple heuristics, such as the tendency to clear the plate, to more complex biobehavioural processes, including individual differences in susceptibility to external food cues through eating traits. Consumers may eat in accordance with available consumption norms or eat opportunistically when large portions are made available. An obvious solution to the PSE is to ‘downsize’ HED meal items and snacks, but whether this strategy is acceptable or feasible is not clear. In adults, the effects of downsizing are mixed and for children and adolescents, as yet unclear. The contention is that for those who are still learning about social norms and appropriate portions, there remains the potential to counter the PSE through downsizing strategies

Portion size and meal consumption in domesticated dogs: An experimental study

Increases in food portion sizes have been identified as a possible contributor to the increased prevalence of obesity in humans. However, little is known about the origin of behavioural tendencies to overeat from larger portion sizes or whether other non-human animals are affected by meal portion size. In the present experimental study, we examined the effect that larger portion sizes have on meal consumption among domesticated dogs (N = 32). Dogs were fed three meals that varied in size on different occasions (150%, 200% and 300% of usual portion size). A repeated measures design was used and food consumption was measured for each meal. Portion size positively affected food consumption, with dogs eating significantly more food as the portion size of meal increased. The effect of portion size on food consumption was also observed when the dogs that finished all available food were excluded from analyses, however not among dogs who did not finish any of the meals. We conclude that the influence larger portions have on food consumption observed in humans is also observed in domesticated dogs. However, it is unclear whether portion size directly biases the amount of food dogs choose to consume, as has been suggested in humans. Further research is now warranted to examine commonalities between human and non-human animal eating behaviour to understand shared behavioural tendencies and their origins

Portion size and later food intake : evidence on the “normalizing” effect of reducing food portion sizes

Background Historical increases in the size of commercially available food products have been linked to the emergence of a worldwide obesity crisis. Although the acute effect that portion size has on food intake is well established, the effect that exposure to smaller portion sizes has on future portion size selection has not been examined. Objective We tested whether reducing a food portion size “renormalizes” perceptions of what constitutes a normal amount of that food to eat and results in people selecting and consuming smaller portions of that food in the future. Design Across 3 experiments, participants were served a larger or smaller portion of food. In experiments 1 and 2, participants selected and consumed a portion of that food 24 h later. In experiment 3, participants reported on their preferred ideal portion size of that food after 1 wk. Results The consumption of a smaller, as opposed to a larger, portion size of a food resulted in participants believing a “normal”-sized portion was smaller (experiments 1–3, P ≤ 0.001), consuming less of that food 1 d later (experiments 1–2, P ≤ 0.003), and displaying a tendency toward choosing a smaller ideal portion of that food 1 wk later (experiment 3, P = 0.07), although the latter finding was not significant. Conclusion Because consumer preferences appear to be driven by environmental influences, reducing food portion sizes may recalibrate perceptions of what constitutes a “normal” amount of food to eat and, in doing so, decrease how much consumers choose to eat. This trial was registered at www.clinicaltrials.gov as NCT03241576

The effect of heightened awareness of observation on consumption of a multi-item laboratory test meal in females.

Human eating behaviour is often studied in the laboratory, but whether the extent to which a participant believes that their food intake is being measured influences consumption of different meal items is unclear. Our main objective was to examine whether heightened awareness of observation of food intake affects consumption of different food items during a lunchtime meal. One hundred and fourteen female participants were randomly assigned to an experimental condition designed to heighten participant awareness of observation or a condition in which awareness of observation was lower, before consuming an ad libitum multi-item lunchtime meal in a single session study. Under conditions of heightened awareness, participants tended to eat less of an energy dense snack food (cookies) in comparison to the less aware condition. Consumption of other meal items and total energy intake were similar in the heightened awareness vs. less aware condition. Exploratory secondary analyses suggested that the effect heightened awareness had on reduced cookie consumption was dependent on weight status, as well as trait measures of dietary restraint and disinhibition, whereby only participants with overweight/obesity, high disinhibition or low restraint reduced their cookie consumption. Heightened awareness of observation may cause females to reduce their consumption of an energy dense snack food during a test meal in the laboratory and this effect may be moderated by participant individual differences

Regional differences in portion size consumption behaviour: Insights for the global food industry

Abstract: Given the influence of globalization on consumer food behaviour across the world, the purpose of this paper is to contribute to the theoretical discourse around food portion size as a global consumption-related symbol and its underlying socio-economic drivers for food industry strategy. Overall, 25,000 global food consumers were surveyed across 24 countries to elicit insight on portion size consumption behaviour as well as consumer perception on eating and drinking small portion size within selected socio-economic classes. The data was quantitatively analysed to answer the pertinent research objectives. In 20 out of the 24 global markets surveyed, large food portion size was statistically established as a prevalent consumption-related symbol. The paper found that there are regional differences in portion size food consumption behaviour, and further disparities exist across age, gender and income status in 24 countries covering all regions, including Australia, China, Mexico, South Africa, United Kingdom and United States of America. The outlined food industry implications reveal that adaptation and standardisation strategies are still relevant in global food and nutrition strategy as revealed by the variations in the preference for food portion sizes across various countries of the world