The Hungry Brain: Outsmarting the Instincts that Make Us Overeat by Stephan Guyenet, Ph.D., originally published in 2017, now available in several formats. I accessed the book via Audible.com.
This is a book that mixes immensely practical, down-to-earth information and advice about our current diet and health issues with somewhat-technical information about the actual biology of the brain. I found some of the biological sections to be rather frustrating, as Guyenet seems to subscribe to the idea that all of our thoughts, desires, motivations, decisions and choices can be boiled down to biochemical reactions at the cellular level. So in an early chapter he goes into an explanation about how our “lizard” brain (or, in this book, our “lamprey” brain) functions, with “feedback loops” putting in “bids.” Guyenet is careful to say that whole process is how scientists understand this all might work, as there’s no way
that the complexity of the human brain can be observed directly. He then uses the example of how a person might make a decision about where to get a meal, with the process ending this way:
As it turns out, the restaurant across town is really good but you don’t feel like driving. The food in your fridge is the cheapest, but it requires cooking. The restaurant up the street is close and cheap, so it puts in the strongest bid and wins the competition. (p. 34)
I’m sure you can see the contradiction here. To say, “You don’t feel like driving” ignores the whole question of where this feeling comes from. Somehow it’s part of one of the feedback loops, but how? It seems clear to me that there’s some other entity here besides the basic biochemical reactions, and indeed the whole book posits the idea that we can make conscious choices about how we eat. So that’s a big caveat about this book to begin with, but now that I’ve gotten that criticism out of the way I can say that on the whole this is an extremely worthwhile book for anyone to read who wants to understand why we eat the way we do. Much of what Guyenet says will be very familiar, but he pulls these familiar ideas into a coherent whole.
So what’s the deal? Well, it’s complicated. And Guyenet refuses to oversimplify or dumb down. There’s no one answer. I especially liked that he refuses to take sides in the fat-vs.-sugar debate.
In popular media, there is a perennial debate over whether sugar or fat is responsible for the obesity epidemic. This has led some people to view obesity research as a team sport rather than a scientific discipline. Allow me to end the debate by stating what most researchers find quite obvious: It’s both. In particular, the combination of concentrated sugar and fat in the same food is a deadly one for our food reward system. It’s also a pairing that rarely occurs in nature…(p. 79)
It’s not that nice olive oil that you used to saute the poblano peppers and shallot for your breakfast omelet this morning (yes, that’s what I did) that’s problematic, to be clear. And guess what? There was no sugar in that omelet, either. But let’s take a look at a couple of junk foods and see how the deadly combo shakes out. I’m going to use two examples that I’ve really liked and eaten in my sugar-laden past, Pecan Sandies cookies and Nacho Cheese Doritos.
Here’s the relevant nutrition info on the cookies:
Each cookie has 5 grams of fat, 3.5 grams of sugar, and a little over 5.5 grams of other carbs, which consist of refined flour. So there are 9 grams of refined carbs in each cookie, making each one a little fat-and-sugar bomb. But a “serving” is two cookies, making things even worse! And who eats only two? Not me, back in the day! I loved to get a package and eat maybe half of it, dunking the cookies in milk as I went. (Thankfully I didn’t do that very often!) As far as I can determine, that would mean that I might eat ten cookies (or more, but we won’t go there). That’s 35 grams of sugar alone, not even counting the other carbs, and 50 grams of fat. Is that even possible? Unfortunately, yes. Total calorie count for those ten cookies: 850. And that doesn’t count the milk.
Ho-kay. On to the Doritos. To be honest, I haven’t ever been a big chip eater, but I do like these (or barbecue-flavored potato chips). One of the big problems with chips, or indeed any junk food, is that the serving size is ridiculously small—but even with these unrealistic amounts the calorie count is pretty eye-popping. So for this flavor of Doritos the serving size is 1 ounce, or “approximately 11 chips.” The only time you’d just eat that serving size would be if you had one of the little single-serving bags, but if you have a big bag, or a big bowlful, there’s no way you’re going to eat that few. Here’s how the “nutrients” shake out, though, for this Lilliputian serving size: 140 calories, half of them from fat, with most of the rest from corn carbs, with a little bit of protein from the various cheese-ish ingredients. There’s no added sugar, but you’re basically just eating corn and oil, with some flavorings. And the husks of the corn have been removed, so you’re eating just the starchy inside of the corn kernel. (Sometime we’re told that this is “whole” corn, but the processing from corn kernels to the corn paste called “masa” does involve treating the kernels with lime, which loosens the husks so that they can be removed.)
And here’s one of Guyenet’s big points: you’d never find similar sources of easy-to-eat, no-preparation-needed calorie-dense foods in nature. We all know this. But he goes into exhaustive detail about how our brains detect the calories we’ve ingested and how little the Pecan Sandies and Doritos in our modern world make us feel satiated, or full. You’ll learn lots about the various hormones that affect appetite. In essence, we evolved (or were created, as I’d say) to eat a lot when we can; we’re driven to consume in a way that’s very counterproductive in our modern food environment.
Guyenet ends with some very, very practical tips for dealing with all this. If you were only going to read part of the book, read the last chapter, “Outsmarting the Hungry Brain.” And I would say, to return to my own anti-sugar position, that while it’s way too simplistic to blame all of our weight/health problems on sugar, that substance is a marker. Any food that has high sugar or other refined carbohydrates is going to be problematic, especially if it’s a convenience food. In other words, that dark chocolate flourless cake that you made for a special-occasion dinner required a lot of effort and some fairly expensive ingredients. A small slice, savored and enjoyed, isn’t going to be a problem. But that whole sleeve of Chips Ahoy! cookies? Well, that’s another matter.
At some point I’m going to re-read and review Michael Pollan’s great book In Defense of Food. He’s the other side of the healthy-eating coin from Guyenet, and a great proponent of eating real food for pleasure. But it’s always good to know the facts. So start with Guyenet and go from there.
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