Do you know that you may be eating more than you think? Impossible, right? Well, maybe not. Dr. Brian Wansink, a professor from the University of Illinois, has been studying consumer behavior for years and has made a career out of investigating the many reasons why we unknowingly overeat. What he has found is that size really does matter - package size, that is - as do visibility, convenience and many other factors that affect our appetites.
Imagine that you and a friend are invited to a party. Once you arrive, you're both offered snack mix - but there's a catch. You must serve yourselves from two different-sized bowls. You choose the large bowl and your friend, who is equally as hungry as you, gets the smaller one. Think you'll both end up with the same amount of snack mix? Chances are, you won't.
In Wansink's study of this exact scenario, students who served themselves from a large bowl consumed 56 percent (142 calories) more than those who served themselves from small bowls, all else equal.
So what does this mean? Well, it illustrates the point that visual illusions play a role in determining how much we eat. And not only does the size of our bowls or plates influence intake, but so does the shape of our glasses. On average, people pour 34 percent more into short, wide glasses than tall, narrow ones without even noticing a difference. Even bartenders, who are trained to pour accurately, over-pour into short, wide glasses compared to tall, narrow glasses. Makes you think twice about those glasses in the dining hall now, doesn't it?
Okay, so perhaps it seems obvious to you that larger package and serving sizes will cause you to eat more of the foods you like, but what about the foods you don't like - say, stale popcorn? Do you think you'd eat more stale popcorn from a large container versus a small? No, because it's stale - yuck!
Well, that's not what happened with moviegoers who unknowingly consumed 61 percent more stale popcorn when it was offered in a large container rather than a small one. This may seem crazy, but no matter what the taste, we lose track of how much we eat as we eat, so eating foods from a larger container will only cause us to eat more.
Now, most of you are probably thinking that all you need to do is pay attention to when you're full: let your stomach be your guide. Unfortunately, this strategy doesn't always work so well either. In another research study, Wansink created the "never-ending" soup bowl to study how much visual cues influence intake. In the experiment, some participants' soup bowls were slowly and imperceptibly refilled (using an apparatus hidden under the table) as the contents were consumed. Those who ate from the bottomless bowls unknowingly ate 73 percent more, but did not perceive
themselves as more satiated than their counterparts who ate from the normal bowls. Apparently, we believe our eyes more than our stomachs.
You also may not realize that convenience and visibility can lead you to eat more, too. According to Wansink's research, the less convenient it is for you to get to a particular food, the less of it you'll eat. In a study of office workers, Wansink placed chocolate candy on the participants' desks where it was visible and convenient. In the second scenario, the container of chocolate candy was placed in the desk - convenient, but not visible. And finally, the container of chocolate was placed away from the desk on a high shelf, which was visible, but not convenient.
On average, participants with candy on their desk ate almost three times more than when the candy was in their desk, and five-and-a half times more than when the candy was on the shelf.
Wansink's work and previous research have also found that our mood, age and even gender play a significant role in determining how much we eat. According to Wansink, women are more likely to want snack-related comfort foods than men, who tend to crave meal-related comfort foods.
Although they have no definitive answer as to why, researchers hypothesize that men are more accustomed to having foods cooked for them and thus prefer hot or prepared foods, while women, who may have played a more active role in cooking, desire convenient and less preparation-intensive foods.
So what can we learn from all this? Well, if you eat in the dining hall, try using the large bowls for things like salad, rather than cereal or ice cream. If you live on your own, take a look in your cabinets and see what size your glasses, plates and bowls are, and try to use the large ones for fruits and vegetables. Also, keep healthier foods on your table or counter so you can see them and easily reach for them when you're craving a snack. And place those chocolate candies far, far away - because out of sight is out of mind.
Information for this article was adapted from Dr. Brian Wansink's research, which can be found by visiting www.foodpsychology.com.
Erin Hennessy is a doctoral student in food policy and applied nutrition at the Friedman School of Nutrition Science and Policy. She has an MS in Nutrition Communication and MPH in Epidemiology & Biostatistics from Tufts' Friedman School and School of Medicine, and a BS in Biology from Tufts University.
