13 January 2016

Use smaller plates - you will serve less and eat less

There's a simple way you can help yourself reduce the amount of food you consume: just change to smaller plates.

Our recent research shows that using smaller plates reduces the amount of food people serve to themselves, and by extension, the amount of food that they eat.


That consumption is linked to portion size is well-known. A review of over 100 studies confirms this effect: larger portions encourage larger consumption, smaller portions encourage smaller consumption.

Now we have found a simple trick which encourages us to serve smaller portions: use smaller plates.

A number of previous reviews examining whether plate-size helped reduce amount consumed provided mixed results. Some concluded plate-size did reduce amount of food self-served, some thought it reduced the amount consumed. But others concluded that plate-size had no effect, and some thought that bowl-size had an effect, but plate-size did not. Virtually all agreed that the the evidence was mixed or contradictory.

However, our most recent review reconciles these conflicting findings and shows that plate-size does help reduce consumption if certain conditions hold, specifically, if the consumer is self-serving to the smaller plate.

If the portion-size is fixed, and served onto a smaller plate, it will not help reduce consumption. 

The important condition is that the person serves their own food onto the smaller plate, as at a buffet. In this situation, using a smaller plate will encourage people to serve less and eat less.

Our review of over 50 studies examining the effect of plate-size shows that the effect is stronger if people are unaware that their consumption is being monitored. If you think you're being watched, then the plate-size effect declines.

This suggests that people adjust their behaviour when they know they are being watched. In social science, this is referred to as a demand effect or demand characteristic. This means that people who know that they are participating in a food experiment, or more simply, know that their consumption is being monitored, appear to modify or change their behaviour.

Our study has two implications. First, if you want to study the effects of modifying how food is served, it is best do so without letting people know what you are doing! Do the study in the real world, not in a laboratory where people know you are studying their consumption.

Secondly, importantly and more pragmatically, if you want to help yourself eat less food, use smaller plates.

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For additional media coverage, see:
     - Egypt Independent 4jan16
     - The Australian 12jan16
     - News.com 12jan16
     - SBS 12jan16
     - Daily Telegraph 12jan16
     - Daily Mail 13jan16
     - Medical News Today 13jan16
     - United Health Care 26jan16
     - AusFoodNews 27jan16
     - Daily Mail 1feb16

For more details, see the Journal of the Association for Consumer ResearchVolume 1, Issue 1, 'The Behavioral Science of Eating' - see links below.

Whether smaller plates reduce consumption depends on who’s serving and who’s looking: a meta-analysis
Stephen S. Holden, Natalina Zlatevska, Chris Dubelaar
Press Release / Full paper

Forthcoming in
The Behavioral Science of Eating
Volume 1, Issue 1 (January 2016)

Editors: Koert Van Ittersum and Brian Wansink

1 comment:

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