What really drives food cravings

Journalist Mark Schatzker makes the case for subconscious desire.

Photo by GR Stocks on Unsplash

Hi friends,

It’s been a while but I return with lots of news. Since my last email, I had a baby (very cute!), moved to Paris (more fun than expected!), and have been working to finish the nutrition and metabolism book I’m co-authoring with scientist Kevin Hall (due out next year!) In addition to the usual notes about stories published or in progress, I’ll be periodically sharing conversations here with people who have changed how I think about food and obesity.

First up: Mark Schatzker, journalist and the author of, most recently, The End of Craving and The Dorito Effect. (Mark’s also a talking head in the 2023 documentary Food, Inc. 2, and a fellow Torontonian). I read Mark’s books several years ago, and keep returning to them because they were so prescient — ahead of the parallel conversations that are unfolding now about ultra-processed foods and the GLP1-based drugs, like Ozempic and Mounjaro, prescribed for obesity. If these foods and drugs expose the hard-wired, physiological systems that shape our eating behavior, Schatzker was among the first popular writers to dive into what we know about how this all works inside of us, and why higher-level brain processes pull the strings more than we may appreciate.

Here’s Mark on how artificial flavors in ultra-processed foods mess with the body’s nutritional wisdom, why culture is too often missing from the conversation about obesity, and the potential unintended consequences of fortifying and enriching what we eat. The conversation that follows has been edited for length and clarity.

Ps. Have suggestions for stories or feedback? I love hearing from you. Send a note!

Julia: An enduring idea in the conversation about obesity is that hyper-palatability is the major driver: junk food or ultra-processed foods have been engineered to be irresistible, we like them too much, and this causes us to overeat and gain weight. Michael Moss popularized the idea in his book Salt Sugar Fat but it’s everywhere. You have a different view. Tell me about it.

Mark: I think the idea that these foods are hitting bliss points is wrong. I’ve spoken to Howard Moskowitz [the researcher who did the pioneering bliss point research for the food industry] and he regrets calling it a bliss point because he said it just got everyone confused. The bliss point for, say, the amount of sugar in a soda just means the most preferred level of sweetness. It isn’t a measure of pleasure or some drug-like high. Howard was approached by food scientists at some of the big companies, in the 80s and 90s, who were researching how to make new snack foods. They never wanted foods that evoked a feeling of bliss. Bliss is not an action, it’s a state of mind. They used words like craveability or “moreish.” They were searching for foods that made people want to eat. 

So I think the idea that these foods are hitting multiple bliss points and that we are sitting ducks misses the mark. When you ask most people about their favorite food experiences, they tend not to say, “It was this bag of Doritos I had” or, “I remember this Burger King on I-80 back in 2009.” These foods unquestionably have a hold on us. But I wouldn't say that that hold is pleasurable. 

Julia: So the idea is that food companies engineer their products to drive this sub-conscious craving, not just for pleasure, and that the craving is driving obesity. In other words, it’s too much wanting, not too much liking, that’s the problem. 

Mark: The stigma is that people with obesity lose themselves in pleasure; they experience too much pleasure. They don't know when to stop, and it's their own damn fault. That's not what the brain scans say. 

The brain imagery shows the real difference between the brains of people with obesity compared to those without is upon receipt of the food cue: when people with obesity see the milkshake or smell the pizza, they experience a spike of wanting that is not matched by the reward they receive upon eating it. If anything, that reward is blunted, whereas the brain [of someone who doesn’t have obesity] will experience some amount of wanting, and then when they consume it, there's also a liking element. So the question you have to ask is, “How could a brain get that way?” 

My view of obesity is that we have altered sensory and nutritive aspects of food in a way that hyper-motivates the brain’s appetite system to consume and store calories. And it just isn't as simple as too many energy-dense foods or salt, sugar and fat. We have changed food in a way that affects a very old but complex brain system we don’t fully understand. The ultimate effect is that millions of brains have been goaded into seeking more calories than they need. And I think our long-held suspicion that we are overdosing on enjoyment grievously misunderstands the problem.

If we look at the cultures that value and celebrate and revere deliciousness the most — in the west, it's Italy, in the east, it’s Japan — they’re super thin. They're markedly more thin than anyone else. I think they enjoy food in a different way. One of the craziest stats I came across was that the French and Italians eat far fewer calories than Americans, and yet it takes them longer to eat a smaller amount of food. Do they chew slowly? Like, what's going on? Well, the food is more of a social occasion. They don't mindlessly eat while they're driving or watching TV. Food is a time for celebration. And the pleasure goes in both directions. Eating with others magnifies the pleasure we receive from food. And the pleasure of eating reinforces the social bond. That's a very different eating experience than just filling the hole.

Julia: You’re touching on something that gets overlooked in discussions about the food environment. The food environment is more than just the foods we have available to us, right? It’s also about cultural norms, how we think about food, how we eat. I’m sitting here in Paris, with, I don’t know, 20 pastry and chocolate shops within a ten-minute walk from my apartment, and a relatively low rate of obesity. The norm here is not to eat these pastries and chocolates in the car, or in front of the TV, as you say. It’s to buy one, sit with your friend or your coffee, and enjoy it.  

Mark: Yeah, that's an interesting point. Because maybe you could argue that some of these beautiful pastries, like chocolate croissants, are ultra-processed foods. Have you ever tried making croissants at home? It’s not easy. But the thing I would say about those pastries is it would be a terrible waste to just mindlessly eat that in your car. [You think] “I'm going to sit down enjoy this.” I think we value it more.

Julia: The policy conversation around diet-related disease right now is very much focused on regulating ultra-processed foods. What you’re saying here, and in your books, is that food culture and appreciation also play an important role. How do you see that aspect translating to policy?  

Mark: [The writer] Bill Buford lived in France, and he was telling me about how [the schools] were teaching his kids to develop a French palate. They would learn about sauces. They would learn about pairing food. The Japanese do this, too. They have classes on food appreciation. And then you look at school lunches in North America. They cost at most a few dollars, often less. I mean, it's unbelievable. And you think, well, how can you possibly serve quality food at that price, and you're feeding your children? Why is this not more of a priority? 

So many of us know we should eat better but maybe we've never been properly educated. I don't mean education in terms of like, this is a calorie This is a protein. I mean, education, like, like this is a bearnaise sauce. This is a dashi. This is what pickling means. I know that sounds silly, but I actually think that's the way. The lesson is the cultures that eat for pleasure, but prize what I call real food—the products of the land and sea—have lower rates of obesity and less diet-related disease. They enjoy food and they are healthier. We need to completely re-think how we think about food. We need to stop obsessing over nutrients and create a culture of appreciation.

Julia: When did you start to think about flavor and its role in eating behavior? 

Mark: It started with a steak I had in Argentina in 1996. It was just a mind-blowing piece of meat. And that led to [my] steak book. I found that so much of the flavor of beef comes from these flavor compounds that are in the grasses that cattle eat — it has what wine lovers call terroir. And then I just got curious about flavor. It's a conversation we never have, which is odd, because flavor is what we all want. Every time we sit down to eat, we want to enjoy the food in front of us. And that comes down to the flavor.

And yet oddly, the conversation we've had about food and health for more than half a century has been from the neck down — how the protein, carbohydrates and fat affect the body. That stuff is important, but it doesn't answer the question, “why did you eat it in the first place?” The reason we eat it is because of an expectation of some kind of pleasure, whether that is the urge for calories, or a hope to be delighted by what you're going to eat. That, to me is the most important aspect of food. And yet it’s the one we talked about the least.

Julia: You argued in The Dorito Effect that the food crisis is a flavor disorder. Can you walk me through what you meant and how your thinking has evolved since then? 

Mark: When it comes to flavor, there are two complementary trends: the food we grow on farms is getting blender and less nutrient dense due to high-output agriculture. Ultra-processed foods, meanwhile, are getting more flavorful because of flavor technology. So we’ve taken flavor away from the foods we should be eating and added it to the foods we should be avoiding.

The relationship between ultra-processed foods and real food is very interesting. There’s a superficial resemblance. Ultra-processed foods are designed to simulate real foods. A ketchup-flavored chip has some of the very same flavor compounds in an actual tomato. But they're actually very unlike it both in terms of the reward experience — the way they make you feel — and what they're made up of, not just the calories, but also the micronutrients. They're totally different. And we weren't designed for it.

I would say I've taken this even further now: it's a disorder in terms of sensory mismatch. The signals that we get from food don't match up with nutrition anymore. In Dorito, I thought the problem was that that these technologies that food companies use, like flavorings, lead us to the wrong foods and then we eat those foods and ingest a few hundred calories, and over the long term that adds up to obesity. What I didn’t fully appreciate is that a very large body needs a lot of calories just to maintain itself. I didn't realize the effect these foods have on the brain — that [the foods] kind of warped the appetite into wanting to eat far too much food. You need a lot of energy to support that larger body. And that made me realize the degree to which people's appetites are really kind of warped.

Julia: Why are some more susceptible to cravings than others?

Mark: One commonality is uncertainty, which is to say that the sensory signals we pick up from food are no longer an accurate predictor of the nutrition that food delivers. The reason we have such a rich sensory system is so that the brain can select the nutrients it needs and predict the physiological effect of food as we eat it. There's this idea I explored in The Dorito Effect and the animal research that flavors can be indicative of micro-nutrition or macro-nutrition. We also know that in a natural food environment, sweetness is indicative of simple sugars, carbohydrate energy and the experience in the mouth of fat equals energy. Now we live in a food environment where those things don't necessarily equal energy. 

If you take a very dim view of the brain's intelligence, well, that's a good idea. Fool it. Make it think it's getting energy. But if it turns out the brain is smart, and it not only tracks what's coming in, but it's got a ledger; it also keeps track of what it got. Fooling the brain potentially becomes a very bad idea. Because then you're creating a situation where the brain is going, “I thought I was getting calories, and I didn't get them.” 

This is a very different experience. And that creates what’s called a “reward prediction error,” or a more simple term is uncertainty. We know how the brain acts in uncertain situations. It responds with motivation. 

Julia: The more unreliable the information we get from food becomes, or similarly, the more uncertain our access to food, the more we want to eat. 

Mark: Yes. This is a universal human response. The reason we gamble is because the uncertainty of the chance you might win is thrilling -- it draws us in. The reason we watch sports on TV is because the outcome is uncertain. Who’s going to win?

What I wonder about is how various forms of uncertainty might work together to alter eating behavior. We know poverty is associated with obesity, but an even stronger association is food insecurity, people who don't necessarily know where their next meal is coming from. They tend to overeat. This is often judged, because people say, “These people don't even have enough money to eat, and they're eating way too much. What an idiotic thing to do.”

But this is a built-in evolutionary response. When food becomes uncertain, it makes sense to eat a little bit more. We know from animal studies that when you make food uncertain — you mess with the animals’ heads by moving food dishes around, and one day, that dish has lots of seeds, the other day, it’s got few seeds, and you change the timing [of feeding] — you can enhance their motivation to eat. 

Think about what it’s like to live in the modern food environment. We know that the sensory aspects of ultra-processed foods — the flavors, the level of sweetness, the rich, fatty mouthfeel — are uncertain. Now imagine someone eating these foods gets evicted, or is getting divorced, is getting bullied, or is starting at a new school. How do these jolts of uncertainty interact with one another?  

Now think about the language we see around ultra-processed foods. They play right into a heightened desire for calories. Foods like a “double down” or a “triple stacker,” or a “Big Mac” are promise of hitting the calorie jackpot. These foods aren’t about the immersive joy of eating. They’re about getting more.  Something has tweaked millions of people to go seek out calories.

Julia: What do you think is getting overlooked in the conversation about the GLP1-based drugs like Ozempic and Mounjaro? 

Mark: It’s the same mistake we keep making. We’re interested in behavior and the effect on the body, namely do people eat less and are they losing weight. I’m more curious about what it feels like to be on these drugs, and I don’t just mean the side effects. I talked to one guy who says his palate has completely changed. He craves fruit and salad. He orders sushi instead of paninis or cheeseburgers. A brother of a friend taking Mounjaro has switched from always eating pizza to eating salmon. Why? What is it about this drug that seems to be changing people’s preferences and urges?

The other thing I’m curious about is how a drug developed for diabetes not only causes weight loss but has also shown positive results for fatty liver disease, heart disease, kidney disease and Parkinson’s. Does overeating drive all these other maladies? Or is there something deeper? Or does the same drug somehow have multiple effects that are unrelated to one another? 

Julia: One of the other interesting arguments you make is that as food became more and more nutritionally bankrupt, we fortified and enriched it to make up for lost nutrition — and that this may be an under-appreciated driver of obesity. What led you to thinking about vitamins?

Mark: My obsession with in vitamins started when I was writing about Fred Provenza’s research into nutritional wisdom. He told me about how when an animal is made to become deficient in a particular micronutrient, if you pair that needed vitamin with a flavor, the flavor would become desired. But then I started to wonder, what if you start putting vitamins in unintentionally, what effect does that have? And I started thinking about what we do with breakfast cereals and bread and rice and so forth. The government mandates the addition of certain B vitamins and iron—that’s called enrichment. When companies do it voluntarily it’s called fortification. But it’s basically the same thing.  

I knew from my research for [my 2011 book] Steak that modern livestock diets are very rich in vitamins and minerals. You can even go on the websites of animal science universities, and they'll tell you about a hog diet, why certain vitamins are important. Then I went back and found research from the 1950s when it was discovered that adding certain B vitamins to hog rations meant you didn’t need to feed alfalfa or green feed anymore. This opened the door to what’s called the “hot ration.” This is what allowed us to take animals off farm fields and put them in confinement. This meant you could feed livestock a diet of almost nothing but corn and soy and add a dusting of vitamins and minerals. It’s an incredibly energy-dense diet.

What these B vitamins have in common is that they are necessary to metabolize calories. So if you really want to create a really calorie-dense diet, you feed calories plus a boatload of B vitamins. That’s what we do to livestock diets. And we do to the human diet by law. They don't do it in Italy, France and Japan. And I think that is one of the reasons they're thinner.

Julia: Maybe you’ll investigate in your research! You’re one of the only journalists I know who also publishes studies on the psychology of eating. How did that start?

Mark: After The Dorito Effect came out, Dana Small — who was at Yale at the time and has recently moved to McGill — invited me to join the Modern Diet and Physiology Research Center. She arranged for me to give a talk about nutritional wisdom at an academic conference, and a researcher — Jeff Brunstrom, from Bristol University — invited me to do research with him. So I’ve had the incredible privilege of working with two incredibly talented scientists. 

One of the challenges for science today is that it is so specialized, that I think it's difficult for scientists to be widely read beyond their very narrow area of interest. I don't mean that as a criticism. Research today has to be narrow, because it is so incredibly focused and detailed. As a journalist and author, I have had the luxury of visiting other countries or talking to old farmers or cold calling entomologists or reading the history of animal science. I knew that in the 1950s, they figured out the feed technology to get animals fat faster, and I thought there's a clue there. But no one else knows that. The scientists who study humans and rats don't know about the history of pig farming. So that's just a lucky thing because I'm such a generalist, and I study adjacent fields that ask similar questions. That’s where the insight comes from. It's just having an unusual luxury these days of reading in other disciplines.