Portion size influences intake in Samburu Kenyan people not exposed to the Western obesogenic environment

Myers, Kevin P.; Brunstrom, Jeffrey Michael; Rogers, Peter J.; Holtzman, Jon D.

doi:10.1016/j.appet.2018.11.007

Cited by 7 publications

(5 citation statements)

References 32 publications

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“…However, it should be noted that in humans PSE has been widely reported in both sexes and across many varied populations of subjects [9,17,19,26,27].…”

Section: Discussionmentioning

confidence: 99%

No evidence that portion size influences food consumption in male Sprague Dawley rats

Naneix

Pinder

Summers

et al. 2019

Preprint

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In studies of eating behavior that have been conducted in humans, the tendency to consume more when given larger portions of food, known as the portion size effect (PSE), is one of the most robust and widely replicated findings. Despite this, the mechanisms that underpin it are still unknown. In particular, it is unclear whether the PSE arises from higher-order social and cognitive processes that are unique to humans or, instead, reflects more fundamental processes that drive feeding, such as conditioned food-seeking. Importantly, studies in rodents and other animals have yet to show convincing evidence of a PSE. In this series of studies, we used several methods to test for a PSE in adult male Sprague Dawley rats. Our approaches included using visually identifiable portions of a palatable food; training on a plate cleaning procedure; providing portion sizes of food pellets that were signaled by auditory and visual food-predictive cues; providing food with amorphous shape properties;and providing standard chow diet portions in home cages. In none of these manipulations did larger portions increase food intake. In summary, our data provide no evidence that a PSE is present in male Sprague Dawley rats, and if it is, it is more nuanced, dependent on experimental procedure, and/or smaller in size than it is in humans. In turn, these findings suggest that the widely-replicated PSE in humans may be more likely to reflect higher-order cognitive and social processes than fundamental conditioned behaviors. Highlights:• Portion size effect (PSE) refers to increased food intake induced by large portions.• Although widely replicated in human feeding studies, it may not exist animals.• Presence of a PSE in animals would shed light on mechanisms, which are not known.• Here, we find no evidence of PSE in male Sprague Dawley rats under a number of experimental conditions.• This suggests that the human PSE is more likely due to socio-cognitive processes.

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“…However, it should be noted that in humans PSE has been widely reported in both sexes and across many varied populations of subjects [9,17,19,26,27].…”

Section: Discussionmentioning

confidence: 99%

No evidence that portion size influences food consumption in male Sprague Dawley rats

Naneix

Pinder

Summers

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, it should be noted that in humans PSE has been widely reported in both sexes and across many varied populations of subjects [9,17,19,26,27].…”

Section: Discussionmentioning

confidence: 99%

“…Despite the abundant evidence for a PSE in humans, food portion size as a driver of eating behaviour is rarely considered in animal studies, so it is unknown whether an analogous effect exists in lab animal models. Indeed, a robust PSE has been shown even in people with very different social norms for eating who live an unmodernized lifestyle outside of the Western obesogenic food environment [9].This suggests the possibility that the PSE reflects a basic feature of dietary psychology driven by relatively low level mechanisms, such as conditioning, which could operate similarly in other species. However, most protocols measuring animal feeding behavior tend to use ad libitum or an excessive amount of food, relative to daily intake.…”

Section: Introductionmentioning

confidence: 99%

No evidence that portion size influences food consumption in male Sprague Dawley rats

Naneix

Pinder

Summers

et al. 2019

Physiology & Behavior

Self Cite

View full text Add to dashboard Cite

In studies of eating behavior that have been conducted in humans, the tendency to consume more when given larger portions of food, known as the portion size effect (PSE), is one of the most robust and widely replicated findings. Despite this, the mechanisms that underpin it are still unknown. In particular, it is unclear whether the PSE arises from higher-order social and cognitive processes that are unique to humans or, instead, reflects more fundamental processes that drive feeding, such as conditioned food-seeking. Importantly, studies in rodents and other animals have yet to show convincing evidence of a PSE. In this series of studies, we used several methods to test for a PSE in adult male Sprague Dawley rats. Our approaches included using visually identifiable portions of a palatable food; training on a plate cleaning procedure; providing portion sizes of food pellets that were signaled by auditory and visual food-predictive cues; providing food with amorphous shape properties; and providing standard chow diet portions in home cages. In none of these manipulations did larger portions increase food intake. In summary, our data provide no evidence that a PSE is present in male Sprague Dawley rats, and if it is, it is more nuanced, dependent on experimental procedure, and/or smaller in size than it is in humans. In turn, these findings suggest that the widely-replicated PSE in humans may be more likely to reflect higher-order cognitive and social processes than fundamental conditioned behaviors. Highlights:• Portion size effect (PSE) refers to increased food intake induced by large portions.• Although widely replicated in human feeding studies, it may not exist animals.

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“…Similarly, in Robinson & Field (2015) participants were directly asked whether the amount they ate was influenced by the information they saw about the number of cookies other participants had eaten and a sizeable proportion of participants reported having been influenced by the number of cookies other participants had eaten. However, it should be noted that participants in Myers, Brunstrom,. Rogers & Holtzman (2019) were asked a similar direct question about which day they believed they had consumed the larger portion but still struggled to answer correctly, raising uncertainty about whether it is the nature of the question asked A further factor that may play a role in whether or not consumers report that their food intake has been influenced by external factors is social desirability.…”

Section: Introductionmentioning

confidence: 99%

“…hunger, satiety, taste) rather than external factors, such as the portion size (Cavanagh, Vartanian, Herman, & Polivy, 2014;Vartanian, Herman, & Wansink, 2008;Vartanian, Sokol, Herman, & Polivy, 2013;. Using a different study design, Myers, Brunstrom,. Rogers & Holtzman (2019) also found that members of the Samburu tribe in Kenya who ate two separate sized portions of food on alternate days, had difficulties identifying on which day they had consumed the larger of the two portions.…”

Section: Introductionmentioning

confidence: 99%

Larger portions make me eat more: Awareness of the external factors that influence food intake

Keenan¹,

Sheen²,

Haynes³

et al. 2020

Preprint

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There is consistent evidence that the amount of food people consume can be influenced by external factors, such as food portion size or the amount of food others are eating. However research studies to date have suggested that people are generally unaware of the influence that these external factors have on food intake. In the present research we directly tested whether consumers are aware of how external factors can affect their food intake. In Study 1 we re-analysed data from a study in which an effect of portion size on food intake was observed and post-consumption, participants were asked whether they believed portion size had influenced their food intake. In Study 2 participants were asked to indicate whether several different external factors known to increase food intake would be likely to increase, decrease or have no effect on how much they would eat in hypothetical scenarios. In Study 1, a large proportion of participants (56%) believed that their food intake was influenced by portion size. In Study 2, a large proportion of participants accurately identified that external factors known to affect eating behaviour would be likely to increase their food intake: portion size (73%), social influence (40%), food variety (75%), and distraction (59%). Together these results suggest that consumers show awareness of the influence that external factors have on their food intake.

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Portion size influences intake in Samburu Kenyan people not exposed to the Western obesogenic environment

Cited by 7 publications

References 32 publications

No evidence that portion size influences food consumption in male Sprague Dawley rats

No evidence that portion size influences food consumption in male Sprague Dawley rats

No evidence that portion size influences food consumption in male Sprague Dawley rats

Larger portions make me eat more: Awareness of the external factors that influence food intake

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