The story of free doughnuts, disposable plates and food waste

Eat me, or don’t. I don’t care, I am just a doughnut. By Anna Maj Michelson from Portland, Estados Unidos — Flickr

When you give students free doughnuts, you expect them to be eaten, devoured, decimated, wiped out. Put those doughnuts on different types of plates, and behavioural scientist in charge of doughnut distribution, and you have a scientific study.

In the US, eating out, on the go, and takeaway meals account for 50% of all the money spent on food. Most of those not familiar with the US eating out rituals awe at the sizes of the portions. The trend of inflating portion size over time led to its doubling in the past 20 years, and nowadays this adds about extra 1500 kcal to an average daily intake of an American. With the increasing waist, food waste also increases. In fact, around third of all the food produced globally is wasted.

Most of us are guilty of pretending to forget about that healthy lettuce (or your equivalent of good-for-you food that requires right mind set to eat it) at the bottom of the fridge only to find a slimy lettuce stew a week later; or that leftover half a portion of failed attempt at risotto (or your equivalent of culinary failure) left in the dark corners of the fridge. We all waste food, many feel guilt, which we try to conceal by burying it, together with the waste food, deep in the bin beneath the wrappers, hoping that environmentally-conscious flatmates won’t spot it, and environmentally-not-so-conscious flatmates won’t be able to catch us out on hypocrisy.

Scientists from different academic battle fields tirelessly work on the question why we overconsume, but only some look at why we over-waste. Williamson et al., in their peer-reviewed article titled Of Waste and Waists: The Effect of Plate Material on Food Consumption and Waste, looked at the combination of doughnuts, students and disposable and non-disposable plates and came to a statistically significant conclusion that

“… people waste more food when eating on disposable compared to permanent plates”.

Williamson et al. conducted 5 studies. In the first study, 56 students were given two doughnuts each on either disposable (paper) or reusable (plastic) plates of the same size and colour, followed by a survey full of questions that, to a behavioural scientist, render the study meaningful. The second study was an online Implicit Association Test with 100 participants to test unconscious bias of food disposability and eatability perception, with food shown on either disposable or reusable plates. In the last 3 studies, behaviour of 320 students was scrutinized in a lunch buffet, where they self-selected the amount of food onto either disposable or permanent plates.

The design of the study served to distinguish between our automatic unconscious classification of disposable plates as being of lower quality, thus the food served on disposable plate as being of lower quality too, and our behavioural perception of food served on a disposable plate as itself being disposable. The results were strongly in favour of the latter: we still think that the food on the disposable plate is good, but we also think it has a disposable vibe to it. In other words, we are more likely to say to ourselves “nah, it is enough food for me, the rest is waste” when eating from a disposable plate.

Indeed, if we are at a party, or a buffet, with a disposable plate in hand, we get the feeling that nobody is going to scrutinize how much food we didn’t eat in the few seconds it takes to place the plate in the bin. However, emptying and washing reusable plate gives enough time to realize the food is a perfectly acceptable leftover for a future consumption.

So next time you organize a party, ditch disposable plates and utensils and serve less food, because nobody said that tackling global issues is going to be easy.

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