Brian Wansink and Collin Payne recently examined the relationship between Body Mass Index (BMI) and eating behaviors at all-you-can-eat Chinese buffets. The researchers found that customers with a higher BMI were more likely to use larger plates and to face the ever-tempting buffet. They were also less likely to use chopsticks (as opposed to a fork) or have a napkin on their lap. Wansink and Payne concluded that, “small changes in one’s environment may lessen one’s tendency to overeat.” (HT: Dmitri Leybman) [%comments]
Nudges by Chopstick
and 
. You can also watch it on 
Oh, hooray, another study mistaking causation and correlation.
Man I love the Freakonomics readers! I read the article, think “that sounds just like correlation to me…” Then I read the comments and the majority of them mention that as well!
Nice job fellow Freakos.
Agree with JES here, a lot of people are missing the point here.
Well how’s this for the causation-correlation nay-sayers:
Give a random sample of buffet eaters small or large plates, and a fork or chopsticks. Track calories consumed as a function of eating surface/utensils and BMI.
Personally, I have a low BMI and I’m a complete pig. I’ll routinely make several trips (3) to and from the buffet. I use as large a plate as I can and I use chopsticks (I can shovel pretty effectively after years of practice). I’m active with a high metabolism.
I think there actually may be some causation to this, and not just correlation.
I know it is much more difficult to eat with chopsticks, so that you may tend to eat less. It also takes more concentration, and I believe many studies have shown that people eat more when they are not concentrating on eating (such as while watching TV, or talking with others. If you are forced to concentrate on eating via using chopsticks, it seems plausible that you may tend to eat less.
Why do we assume the high-BMI individuals overeat? They could be eating normally (that is, to maintain their weight). Larger people need to eat more.
Of course it’s another matter entirely whether they should be eating less, so that they lose weight, but presumably not everyone wants to do that.
Forget all the causation-correlation nonsense, this is just common sense: fat people eat more food faster than skinny people. Really? We needed a study to prove that?
I also agree with JES. If you doubt the causality, pick up a copy of “Mindless Eating.” They do several carefully controlled experiments to determine which environment factors influence our eating behaviors.
http://www.mindlesseating.org/