How to Nudge your Xmas dinner even better

By Katrine Lund Skov & Pelle Guldborg Hansen

Recently we wrote about how the size of your plate affects how much you eat. But at Christmas people take eating a step further. In Denmark alone 50 – 100 people end up hospitalized because they eat too much.

In this post we continue in the food & Christmas section, and let you know, how to nudge your family to love the Xmas dinner even more – after all you have prepared this for several hours, or perhaps even days!

First of all you can put a lot of salt sugar and fats in the food. Our ancestors ate salt to prevent dehydration, fat helped them to fill up their calorie reserves for winter seasons and sugar helped them know the difference between sweet eatable berries, and sour poisonous berries (Wansink 2008:188). This has given humans an insatiable craving for these ingredients, which you can take advantage of. Though, if you want your family members to be able to walk around the Christmas tree you probably shouldn’t.

Confirmation bias at the X-mas dinner

Wansink's bestselling book

Instead use our plan B: Just tell them how delicious it’s going to be. Let them know it’s home cooked. How you have used special recipes. How creamy, juicy and delicious you have prepared it to be - use details to tell them exactly just how tasty your home cooked Christmas dinner will be.

At least this is what American nutrition professor Brian Wansink’s (1960) suggest as to how to turn the confirmation bias to our advantage: If we believe that the food we are about to eat will taste good, our taste buds can be preprogrammed.

To examine just how effective the confirmation bias is, Wansink sat up a test where 32 persons had to test the taste of a new strawberry yoghurt flavor. Wansink didn’t want the appearance of the yoghurt to have any influence on how well they liked it, why they ate it in a dark lab. 19 contestants told that it had a great strawberry taste, and one contestant even said it was her new favorite. There was just one twist to the test – it was not strawberry yoghurt, it was chocolate yoghurt. Just by telling the contestants it was strawberry yoghurt, their taste buds got preprogrammed and thereby told them so. Restaurants have used the trick of our confirmation bias for several years. Wansink calls this the magic of the menu card. Similarly, you can preprogram your guests to enjoy your Christmas dinner even more than they probably already would have merely by telling how delicious it is.

Merry X-mas from the iNudgeYou-team!

PS. Make the table decoration beautiful. Just by having a great mood setting atmosphere your family members will enjoy the whole arrangement even better, which also will effect their appreciation of the dinner.

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). 

How to grow your own nudge

By Pelle Guldborg Hansen

Credit: Patou

Children, vegetables and fruit
The last couple of years I've heard several professionals say that the key to getting kids to enjoy healthy food is having them participate in preparing dinner. The idea seems to be that by doing this it will make them more open to trying out new kinds of food and thus also - so the argument seems to go - be more positive towards preparing and eating healthy food.

To me this idea seems to be somewhat naïve. In its strongest version I take the argument to be that some sort of effect resembling the endownment effect should be established by the process of food preparation. But why on Earth should this only pertain to potatoes and not to french fries?


When I was a kid...
When I was a kid I had chickens. That meant that every morning I could eat a great tasting soft-boiled egg. We also grew potatoes in the garden... and apples, carrots, pears, plums, strawberries and much more. Oh boy, did I eat a lot of fruit, vegetables... and eggs!

Today I struggle to get my 7 year old son to eat fruit, eggs and other healthy foods. I'm part of that big army of parents repeating every night "eat your vegetables" and "taste this fruit". But despite the fact that we have access to more varities of exotic fruits than ever, it doesn't seem that kids find it easier to enjoy the taste of fruit, vegetables... and eggs.

Now, of course I have tried regulation. You have to eat so-and-so before you can watch cartoons! But for some obvious reasons this doesn't really succeed in making him enjoy his fruits and vegetables. I've also tried the "sticks and carrots" approach to the sticks of carrots. If you eat so-and-so, you'll get (or don't get) this-and-this. But that doesn't really seem to have improved my goal (i.e. making him enjoy healthy food), since it only makes it a means to his ends.

In sum, the situation that I share with an army of parents calls for a nudge. That nudge doesn't seem to be one having kids preparing their own food, but rather having them grow it. That's right. Tonight I'll say:

"Son. When I was a kid we grew our own nudges. I think it's time for you to do the same."

After all, while you can grow potatoes, you can't grow french fries. Now I just have to get find some bags of top soil and carry it to the 4th floor!