Ladies and gentlemen of the jury, one of these two ice cream delights is from Grom gelateria in Italy, the other from Cold Stone Creamery in the United States. Without reading the labels, can you guess which is which?

If an alien life form visited the Earth, he might conclude that Americans are some kind of storage vessels for large amounts of food and energy, perhaps bred to preserve the entire species in times of scarcity. Yet it seems fairly unlikely that we are preparing for such harsh times. So what are we doing?

“No Thank You, My Eyes are Full”
Research has shown over and over again that humans aren’t quite so adept at judging what amounts to a human-sized portion of food. Instead of judging on caloric density or volume, our brains find it easier to judge on relative sizes. For instance, if I offer to give you a piece of pie on a large plate or the same piece of pie on a small plate, you should choose the small plate - you will consistently report feeling fuller afterwards. In one recent study, some participants drank soup from “self-filling bowls” while others drank from regular bowls but could ask for as many free refills as they wanted. At the end of the meal, both groups reported being about equally full and estimated that they had eaten about equally much, but those using the “self-filling” bowls had eaten 73 percent more soup.

Why do our brains fail us so miserably in these situations? For starters, our brains evolved for consumption in a time of scarcity. Evolution trained our brains that food was a precious resource to not be wasted. Finish your buffalo because we might not have more for a couple days. That’s the traditional answer. Second, there’s a significant information delay from the tummy to the brain. If you think of your stomach as a computer, it takes 15-20 minutes to “process” the food data and send signals to your brain letting it know that you are full. In contrast, your brain can access visual information instantly. So for this reason, it makes sense for your brain to use visual cues.

An Arms Race of Epic Portions
Americans buy more diet books than any other country on Earth and are obviously somewhat concerned about their weight. Now imagine if American restaurants served smaller portions. These people would find it easier to lose weight, people would likely feel just as full, and the restaurants would save money on the extra food. Everyone is better off! So why the escalation to epic portions anyways?

To answer this question, we need one important fact about how the brain makes decisions - relativity. When we make decisions, we don’t judge the quality of two things independently; we compare them. We put them next to each other and we look for differences… any differences. An easily detectable difference will often play a stronger role in our decision making than differences that are more important to us but harder to detect.

Food is about the cheapest cost for a restaurant, especially in the US. Labor and real estate are far more expensive. Larger portions are an easy way for one restaurant to distinguish themselves from others. It’s also an easy way to get people to pay more.

Most cafes in Torino offer only one size of coffee. Starbucks offers four. You could order a “short” (which still dwarfs the typical coffee cup in Torino) but you won’t, because it’s not even on the menu at most Starbucks. You could also order a Tall at 12 oz., but again, you probably won’t, because for just a couple of dimes more, you can get a Grande at 16 oz. But why stop there? For even less dimes, you can upgrade to a Venti at a colossal 24 oz. Never mind whether you want that much coffee. Economically, it’s a no-brainer, you take the “good” deal. And Starbucks is happy you did; it’s a good deal for them as well. The extra cost of giving you the extra fluid ounces of coffee is pennies. Just as for other restaurants, their costs are labor and real estate. The product itself is dirt cheap.

Now imagine if instead of 12, 16, and 24, your brain was presented with a different list of easily ordered numbers: 340, 470, 600. Those are, respectively, the number of calories in a Tall, Grande, and Venti Vanilla Bean Frappuccino Blended Creme. Your brain might now seize upon the easiest criteria for distinguishing the three and go with the Tall, the obvious candidate for “healthiest” drink of the bunch.

Why US?
So why Americans? The brain quirks we’ve discussed are universal and not limited to only those in the US. So there must be something else about us.

For starters, food is incredibly cheap in the US due to our relative wealth and huge farm subsidies. It’s easy for restaurants to offer those “great deals” that let you get twice as much food for only 20% more money.

A second answer is offered by Michael Pollan in his book, The Omnivore’s Dilemma. The United States has a relatively nonexistent food culture. Other countries like Italy have strong traditions on food that dictate what constitutes a good size and content for a meal. A coffee simply is that tiny little cup pictured above. These traditions were established many years ago when food was not so abundant. Americans on the other hand are more susceptible to diet crazes, eat out more often, and don’t have a long history of established food traditions.

If Americans want to avoid becoming sedentary blobs of consumption (see the recent Pixar film Wall-E), something will have to change and it won’t be our brains. Or will it? Biological engineering might one day allow us to upgrade the signal pathways from our stomach to our brain, so that we realize we’ve had enough long before that third piece of pumpkin pie.

More immediately (and maybe less invasively), the government might limit the size of portions offered in restaurants, dole out subsides for smaller portions, or require restaurants to post nutritional information as prominently as size and price. Vast amounts of government money are spent paying medical costs that result from obesity-related illnesses so they have both an incentive and some measure of legitimacy in interfering.

Some ending questions.

• Any other ideas on why large portion sizes are so prevalent in the US?
• Would you accept biological engineering to help you make better food decisions?
• Would you support government intervention in this problem?
• Do you have a better solution?