The consistently amazing Jonah Lehrer offers another example of the Ikea Effect:
Why do the microwave and frozen dinner inexorably lead to obesity? According to the economists, the cheapness of calories (both in terms of price and time) has led us to dramatically boost consumption. Food stops being something we make and create — it doesn’t require very many lever presses, so to speak — and becomes something we simply ingest. Eating just gets easier. And then we get fatter.
But maybe we’re not just consuming more calories because they’re available at such a low cost. Maybe we’re also consuming more calories because each calorie gives us less pleasure. The lesson of those lever-pressing mice, after all, is that when we don’t work for our food — when it only requires a single press, or a few whirls of the microwave — it tastes much less delicious.
That hypothesis leads me to this study, published in 2008 in Science. The experiment involved giving subjects sips of a chocolate milkshake inside an fMRI machine. The scientists were interested in the activation of the striatum, an area rich in dopamine neurons and involved in the processing of hedonic rewards. (When your striatum is excited, life is good.) Sure enough, obese people tended to have reduced activation in the striatum after sipping the ice cream treat, which led to increased consumption. In other words, they kept on consuming the milkshake in a manic search for satisfaction.
A second study found that, over time, people with a polymorphism that leads to reduced dopamine receptors in the striatum also tended to put on weight, suggesting that obesity is, at least in part, triggered by a shortage of neural pleasure. Of course, this contradicts the popular (and deeply unfair) cultural stereotype of obesity, which assumes that people who are overweight are gluttons, unable to resist temptation. In fact, they are the opposite of gluttons: The reason they eat too much is because they don’t enjoy their food enough. They keep on sipping the milkshake precisely because it isn’t pleasurable.
Maybe this is why Americans need ever larger portion sizes: Because we didn’t make the milkshake ourselves, because that dinner only required a few minutes of work, we need to consume more calories to get the same baseline of satisfaction. The solution to this problem, of course, is simple: We need to take time to make dinner. Instead of buying frozen french fries, make a risotto. The 30 minutes of stirring will make the end result much more delicious.
Jonah Lehrer is the author of How We Decide and Proust Was a Neuroscientist.