Green nudge: trayless cafeterias for reducing food waste

We do throw out an incredible amount of food, and little do we think about the role that trays in cafeterias play in this. But the truth can be surprising.

A tray of spicy dishes
At the moment I’m living in wonderful Singapore. A couple of days ago I got shown around the city by an Indonesian guy, who lives partly in Indonesia and Singapore. After a long walk at the Marina Bay, we went for some Asian food at a cafeteria. Asian food is amazingly delicious, but, as you probably already know, it is usually also really, really spicy.

In the cafeteria I grabbed a tray and walked around selecting a series of dishes – and as long as there was room on my tray, I kept putting food on it. But imagine the size of a tray, and compare it with the size of an average plate - it may be difficult to eat up a plate of food, but very few people are actually able to eat an entire tray of food! Unintentionally, I was headed either for a severe stomach ache, or making a rather large contribution to the global problem of food waste.

After trying most the food, burning of my tongue and sweating chili out of my forehead I had to give up. This definitely wasn’t in the favor of my Indonesian friend who pointed at me: “Eat up! Don’t throw food away!” And he couldn’t be more right. (Though, I am pretty sure, that I would have pasted out eating up the rest).

How trays contribute to food waste and how to prevent it
We do throw out an incredible amount of food, and little do we think about the role that trays play in this. However, a study at...

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How to nudge your bartender to give you a bigger drink

By Katrine Lund Skov & Pelle Guldborg Hansen

Low on cash?
At the end of the month, when the money is low, we often find ourselves Friday night at a bar stuck with the problem of maximizing fun (read: alcohol) at the lowest cost. To many this means ordering cheap brands, but here’s how to nudge your bartender to fill the glass more than he intends so you can stick with the good stuff.

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In the book Mindless Eating by Brian Wansink, Wansink explains how the shape of glasses has an effect on just how much people pour into them. As it turns out, people pour 20 to 30% more fluid into a glass when it is short and wide rather than tall and slender.

If you have problems believing this, then you might want to read up on Wansink’s study.

In this Wansink asked 45 bartenders pour up 40-ml. of liquor into various types of glasses. While some of the bartenders were men, some women, some young, some old, some working at expensive restaurants serving Dom Pérignon, others working at places usually serving tequila shots, they all had at least 5 years of experience. While the bartenders didn’t have much of a problem when the glasses were tall and slender, none of them were able to pour the right amount of liquor into glasses when these were short and wide. Instead, they poured 37% too much up.

Thus, if you want to maximize the amount of liquor relative to cost, please ask your bartender to give you a wider, though shorter glass, instead of the regular tall and slender one. You might just end up with a bigger drink which ultimately will allow you to stick to the good stuff.

Low on calories?

Fortunately, this nudge can also be used the other way around. When serving expensive or high calorie drinks for yourself or for your dinner guests, give them tall and slender glasses. For water, use the short glasses.

How come a simple design can fool us?
If you take a look at the figure to the right, which line do you find longer?

The vertical one!

Nonetheless, this is not the case. Both lines have the exact same length. However, we automatically find the vertical line longer due to a visual illusion. This is also what happens when we, or even the experienced bartenders, are pouring up liquor. The tall and slender glasses appear smaller, than the low and wide glasses, why you can nudge a bartender, your guests or even yourself to drink more or less all depending upon your intentions.

P.s. One of us, Pelle, used to be a bartender for many years. He also makes the mistake. Still, as you probably have noticed most regular restaurants have adopted the standard counter nudge of using measuring cups and like instruments. More expensive restaurants, however, are still usually too proud to use such rude instruments for their fine liquors.

Nudge yourself to a healthier life: plate size

By Pelle Guldborg Hansen

This is a classic. Still, we thought that X-mas might just be the right occasion to write about Wansink's famous study of the effect that your plate's size has on your intake of calories.

Mindless eating
Brian Wansink is professor in consumer behavior and nutritional science. However, to most people outside of academia he is perhaps best known as the author of Mindless Eating: Why we eat more than we think (2006).

The multiple studies of food psychology and behavior reported by Wansink in Mindless eating carries a simple message: most of our eating behavior occurs through non-conscious processes and is thus also affected by cues, feats, and factors that we do not know about. In the language of Kahneman: most of our eating behavior is controlled by System 1.

Plate size
One of the features that affect how much we eat and hence also how many calories we consume is plate size. In a study carried out by Wansink and his team it was shown that moving from a 12-inch dinner plate to a 10-inch dinner plate leads people to serve and eat 22% less!*

Obviously, plate size shouldn't have any effect on an unconstrained and hyper-rational person. Such a person would have a plan as to how much to eat and know exactly how to carry this plan out to perfection.

Such ideal behavior is by no means unattainable. Heck, I once had great success monitoring my calorie intake through an electronic food diary called Madlog. The only problem was that my everyday life didn't allow be to give that much attention to closely monitor my intake. Weighing and measuring everything that I was eating throughout the day while doing my job and enjoying myself with my family turned out to be impossible. It just required too much effort and attention from system 2.

Consequently, as so many others, I need to find some simple and smart ways and heuristics to nudge myself to a healthier lifestyle... and when we can't manage to monitor the details of everything we eat, plate size does matter.

Why plate size matters
There are several causes to why the size of your plate matters. For one, the size of your plate effects the visual representation and following evaluation of how much food is on your plate.  

Of course, while this may cause you to put more food on your plate, it isn't sufficient for making you eat more. Unfortunately, your brain takes care of that - often even if you think about.

For one, food on a plate in front of you acts as a multi-level sensory cue for your brain to activate eating behavior and continue eating until you reach your physical limit. Behind this behavior lies the fact, that we didn't evolve at McDonalds, but in environments where scarcity of food was the fundamental human condition. Perhaps that explains why my Grand mom always says "eat while you can".   

Second, it takes a while before your stomach gets around sending that signal to your brain, that you're full. Some say that it takes as much as 15 minutes - and those 15 minutes can become very dangerous for your health.

Finally, there are social norms associated with leaving food on your plate. These might in turn be associated with norms of masculinity, politeness and norms of sustainability - it's masculine to eat much, it's not polite to leave food on the plate when you're a guest and it's just plain wrong to throw out food. All of these values enforce the norm of finishing your plate - especially when you think about it.

Do yourself a favor - nudge thyself
Now there is little chance that your brain or stomach will change. Further, the values coordinated through social norms may be to our liking and thus a matter of preference that it is not our job to judge or influence.

But fortunately, the size of our plates is under your control and thus you can nudge yourself. By simply finding some smaller plates you can affect the amount of food you eat. Also, you may do your guest a favor at the X-mas dinner - after all, it's unfortunate to kill your guests slowly by having norms of masculinity, politeness and sustainability finish them off.


Other blog entries on food and health:

How to grow your own nudge

Why nudging is better than the fat tax and other tools of the trade

A Nudge to walk around the Earth

Read more: 
Wansink, Brian (2006) Mindless Eating: Why We Eat More Than We Think. Bantam Books.

* "The Perils of Plate Size: Waist, Waste, and Wallet (2008), Brian Wansink and Koert van Ittersum, Journal of Marketing (the paper is not yet published, but it may be downloaded here).