Why You Eat What You Eat: A Neuroscientist Explains

WGBH Radio’s Henry Santoro interviewed author Rachel Herz about her latest book, “Why You Eat What You Eat: The Science Behind Our Relationship With Food.” The following transcript has been slightly edited for clarity.

Henry Santoro: Don’t look now, but we're about to enter the eating season. There's Thanksgiving and Hanukkah, Christmas, New Year's and the craziest eating day of all, Super Bowl Sunday. Crazy food days, all of them. Enter Rachel Herz, a locally based psychologist and neuroscientist who teaches at Brown University in Rhode Island and at Boston College. Her latest book is, “Why You Eat What You Eat: The Science Behind Our Relationship With Food.” So, let's dig in.

Good morning, Rachel.

Rachel Herz: Good morning, Henry.

Santoro: Thank you so much for coming in. We first met onstage at a food event at Harvard University not that long ago. I was hosting, and you were a guest speaker at the segment that was called, “Our love affair with doughnuts.” And, it's doughnuts that are on the cover of your book. So, let's just start there, from a scholarly point of view. Why do we love doughnuts so much?

Herz: Well, we love doughnuts so much because they contain sugar and fat, which are the most delightful things for our tongues to taste in terms of our brains lighting up with reward and pleasure and even pain-killing endorphins. So those two components of food feel good to us to eat, and doughnuts are a perfect combination. Plus they've got carbohydrates, which have serotonin, components to releasing and calming effects, and so forth.

Santoro: But what about the after-effects — that gut-wrenching fullness feeling that we get?

Herz: So, the problem with our current habitat humanity.

Santoro: If we have one doughnut, it's probably fine. If we have six, it's probably not fine.

Herz: Yeah, and the sort of mantra behind my book is, I don't want anyone to restrict themselves from eating anything that they want to eat. I mean, if you restrict you will then go on a binge. And that's one of the reasons why most diets fail. So, the idea is: Don't restrict yourself, but think about what you're doing. Ask yourself the question, 'Is the pleasure also worth the calories and other health consequences at that very moment.'

Santoro: So here we are, looking the holidays in the eye and we're being bombarded by food advertisers who seem to know all our vulnerabilities. What's the consumer's best approach or best defense to the Food and beverage marketers?

Herz: I think it's just using your own self as a guide and trying not to be influenced by everything that's being bombarded out to you. And to really think about the fact, like if you're going to a party, maybe you do have to prepare things, or you said you were going to bring things. So that's one thing. But just because Thanksgiving is coming up doesn't mean that you have to stock up on extra cheese and crackers and cookies and so forth just for you on a regular shopping trip. So, I think that that's one of the things. The other is to realize that when you're at a party and when we're in social gatherings, we tend to eat more because we tend to be both socializing and therefore distracted from what we're eating, plus there's a lot of variety in a lot of goodies there. And the more variety there is, the more we tend to eat. It’s like the Thanksgiving dinner is the is why we eat 4,500 calories at that one meal. And you know that's basically double of an average day.

Santoro: That's when the grazing starts.

Herz: The grazing, and so the variety and the socializing.

Santoro: Okay. So here we go: It's Thanksgiving. Everybody's gathered round the table. Will the person closest to the turkey and gravy eat more of it than Uncle Bill, who's sitting at the kids' table with the kids?

Herz: Yes, he will. Whoever is sitting closest to the turkey is going eat the most. And whoever is sitting next to the mashed potatoes is going to eat the most. We are very much motivated by what is in front of us. And it's also very easy. You don't have to go through the whole awkwardness of asking, 'Could you please pass the turkey tray?'

Santoro: Rachel Herz is the author of the book, “Why You Eat What You Eat: The Science Behind Our Relationship With Food.” Rachel this has been fascinating, thank you so much.