Professor Chris Dubelaar, a professor in the Department of Marketing of the Deakin Business School, worked with Dr Stephen Holden (Macquarie Graduate School of Management) and Dr Natalina Zlatevska (Bond University), to determine once and for all if the commonly held view that smaller plates lead us to eat less.
The results of the study, published in the inaugural issue of the Journal of the Association for Consumer Research “The Behavioral Science of Eating”, showed that plate size did have an effect on the amount of food participants consumed but only under certain circumstances.
Professor Dubelaar said swapping to smaller plates could be a good option for those looking to shift extra kilograms gained over Christmas.
“Literally having too much on our plates is contributing to the growing obesity problem,” he said.
“Based on the results of this study, using smaller plates could form part of a range of small changes people can make to help ensure they do not overeat.
“Efforts towards downsizing portion sizes all fit within a larger field of small steps used to modify the consumption environment so as to nudge people towards healthier and less wasteful behaviours.”
While it is commonly thought that smaller plates lead to us eating less, the evidence is not that clear with some studies showing that this is the case while others report that plate size has no effect on food consumption. It was this confusion that motivated the researchers to conduct the current study.
They analysed the results of 56 food studies, that collectively involved 3507 participants, to answer the question of whether smaller plates reduced food consumption and, if that was the case, under what conditions did plate size have an influence.
The results showed that plate size had a considerable effect on the amount of food consumed but only if the consumer self-served their portions, or portion size was varied in line with plate-size.
Across all the studies combined, doubling the plate size led to an average 44 per cent increase in consumption, with smaller plates (that were half the control plate size) resulting in a reduction of 20 – 25 per cent when compared with larger plate size. Plate size had no effect on average in situations where portion sizes were held constant across plate sizes.
Whether participants were aware that they were participating in a food study or not was also found to be a major driver of the effect. If participants were not aware that they were participating in a food study, the effect of manipulating plate size was significantly larger.
“The results of our research have resolved the confusion around plate size and how much food we eat,” Professor Dubelaar said.
“Our analysis supports the notion that plate size positively influences consumption when portions are self-served or varied in line with plate size, and if people do not know they are being watched.”
Professor Dubelaar explained that endless product choices and supersized marketing are part of the reason for our growing waistlines.
“Our body is not good at telling us we’ve had enough food. Basically it evolved in times when food was scarce, so if you can eat more then go for it, because tomorrow you may be hungry! That is also why we’re so good at storing fat,” he said.
“We are also eating more because portions, plates and packages are larger, yet we have hardly noticed this change.
“Based on what we now know through this study, wide-spread, long-term use of smaller plate sizes may help to reduce how much we eat and perhaps obesity in precisely the same way that we have become blind to how large plate sizes have become over time. Continual use of smaller plate sizes may be both habit forming and good for our health.”
The study, ‘Whether smaller plates reduce consumption depends on who’s serving and who’s looking: a meta-analysis’, has been published in The Behavioral Science of Eating, the Journal of the Association for Consumer Research.
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