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

Situating interventions to bridge the intention-behaviour gap: A framework for recruiting nonconscious processes for behaviour change

This paper presents a situated cognition framework for creating social psychological interventions to bridge the intention–behaviour gap and illustrates this framework by reviewing examples from the domains of health behaviour, environmental behaviour, stereotyping, and aggression. A recurrent problem in behaviour change is the fact that often, intentions are not translated into behaviour, causing the so-called intention–behaviour gap. Here, it is argued that this happens when situational cues trigger situated conceptualizations, such as habits, impulses, hedonic goals, or stereotypical associations, which can then guide behaviour automatically. To be effective in changing such automatic effects, behaviour change interventions can attempt to change situational cues through cueing interventions such as priming, nudging, upstream policy interventions, or reminders of social norms. Alternatively, behaviour change interventions can attempt to change the underlying situated conceptualizations through training interventions, such as behavioural inhibition training, mindfulness training, or implementation intentions. Examples of situated behaviour change interventions of both types will be discussed across domains, along with recommendations to situate interventions more strongly and thus enhance their effectiveness to change automatic behaviour. Finally, the discussion addresses the difference between tailoring and situating interventions, issues of generalization and long-term effectiveness, and avenues for further research

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 Portion Size and Unit Size on Food Intake: Unit Bias or Segmentation Effect?

Objective: The "unit bias" has been proposed as an explanation for the portion-size effect; people consider a single unit to be an appropriate amount to eat and thus eat more when served a larger unit than when served a smaller unit. We suggest that the unit bias might be better characterized as a "segmentation effect," such that people eat less when a unit of food is separated into smaller subunits, but may eat more than a single unit. Furthermore, we suggest that portion-size effects should be independent of this segmentation effect. Method: In Study 1, female participants (n ϭ 87) were served either a small or large portion of food that was either presented in the form of a single unit or multiple individually wrapped units. In Study 2, female participants (n ϭ 42) were served a fixed portion of food that was either presented in the form of a single unit or multiple units presented on separate plates. Results: Across both studies, there was no evidence that participants prefer to eat a single unit. Participants served multiple smaller units did eat less than did participants served a single larger unit, even when the overall portion size was the same, but the amount eaten was consistently more than a single unit. Furthermore, perceived norms of appropriate intake mediated the effect of unit number on food intake. Conclusions: These findings suggest that a segmentation effect, rather than a unit bias, is driving people's food intake, with implications for designing interventions aimed at reducing excessive food intake