Darwinian Psychology-Part II: Why we eat junk

There’s no doubt about it, the average American diet is atrocious. Give us the 44 ounce softdrinks, Big Macs, ice cream, and snack cakes, and we’ll take that every time over a healthy diet of fruit and vegetables. Obesity is referred to as an “epidemic” in America. I agree with all of that.^[1] Here’s where I get off of the bus:

Maybe your mother didn’t cry, “Mangia!” when you ate dinner, like mine did. Still, you’re likely to whisper it to yourself. That’s because you possess a simple survival impulse: Eat until sated. Our neanderthink legacy is to store as much energy as possible, since calories were scarce and uncertain for most of human evolutionary history and our metabolism was set to guard against the possibility of starvation tomorrow. The problem is that eating more doesn’t sate us; we merely recalibrate how much we think we need.

Our evolved mind-set on food hinders us in several ways. Our instincts tell us to keep eating well beyond when we are sated. Worse, the foods we crave—calorie-dense fats and sugars—were once rare and valued as a bulwark against starvation; now they’re plentiful and harmful in excess. We don’t crave plants, precisely because they were more abundant in our past. And if we do manage to temporarily gain a handle on the gustatory Disneyland in which we live, our dietary rigor plummets once we’ve lost weight.⁽¹⁾

So, the notion is that our Neanderthink makes us do it. For the sake of argument, let’s say I concede this point for a moment. What is the recommendation?

We’re good at rationalizations to avoid governing our food intake. We tell ourselves, “I can get away with eating this delicious morsel,” or “It’s too hard to deny myself this scrumptious ice cream.” By yielding to such urges, we ratchet upward the amount of sugar and fat we crave, because we are tampering with a hormonal system finely attuned to the lack of such concentrated energy. On the savannah, the sweetest confection was wild fruit.

Michael Pollan, author of The Omnivore’s Dilemma, famously summed up what you need to know to consume healthfully: “Eat food. Not too much. Mostly plants.” The method by which we might hew to this Paleolithic regimen can also be summed up in seven words: “Dieting gets easier if you don’t cheat.”

So the question is, how do the recommendations actually follow from the just so story? They don’t. It’s just, “Don’t eat too much, and eat mostly plants. Oh yeah, don’t cheat.” But this goes back to the premise of my original post, and that is that the Darwinian Psychology narrative is thought to add scientific authority to whatever is being discussed. Forget the fact that the conclusion does not follow from the premise in the article. That is irrelevant to why these folks invoke a Darwinian just so story. They think it adds credibility. For me, they just prevented the story from being printed out and handed to my patients, which could have been beneficial.

The same periodical also published an article entitled, How to Be a Good Storyteller not long before.⁽²⁾

Perhaps they find these articles unrelated, but I found them to be very related:

Stories also entertain, educate, and instill moral values—sometimes all at once. We can all tell narratives, whether in the classroom, the boardroom, or the living room, but it takes practice to become a fine raconteur.

It seems the folks over at Psychology Today have been getting their practice.

—References—
⁽¹⁾ Neanderthink: An Outsize Appetite, Courtesy of Evolution, Nando Pelusi Ph.D., (11/17/08), Psychology Today
⁽²⁾ How to Spin a Good Story, Brian Andrew, (10/20/08), Psychology Today

—Footnotes—
^[1] I have a simple experiment which I use to teach my patients about their diet. This one has to do with sugar, and more specifically folks who are addicted to soft drinks. Go two weeks without any soft drinks (it actually doesn’t matter if it’s a diet soft drink or regular), and then go out and buy the biggest soft drink you can. Then it will be clear to you what it does to your mind and body. This is something that has worked in each case. In fact, the research shows that drinking just one diet soft drink daily increases the risk of being overweight to an extent that is greater than regular soft drinks, although not by much. One diet soft drink daily increases your chances by approximately 42% whereas one sugar filled drink increases your chances by 38%. It goes up with each additional drink per day.