Plain English with Derek Thompson

Why Are Americans So Unhealthy? Part I: Is Ultra-Processed Food Killing Us?

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Derek Thompson

About the episode

Americans die younger and faster than the residents of almost every other rich country. Why? There’s gun violence, drug overdoses, and car crashes. Young people are much more likely to die from these accidents than those in other countries.

Just as importantly, Americans are more likely to die from chronic illness, especially heart disease and metabolic diseases. We eat more and worse food. We’re arguably exposed to more environmental toxins. We move around less, too. Kevin Klatt, a research scientist at UC Berkeley and a nutritionist, joins us in the first episode of our new miniseries on health. We take on the hottest topic in the diet world today: ultra-processed foods.

If you have questions, observations, or ideas for future episodes, email us at PlainEnglish@Spotify.com.

Summary

  • In the following excerpt, Derek and Kevin Klatt dive into how Kevin entered the diet research field and begin to explore how diet impacts the high rates of obesity and chronic illness in the U.S.

    Derek Thompson: You are a diet and metabolism researcher. How did you get into this field, and why did you find that subject so interesting?

    Kevin Klatt: Oh, gosh, very few people actually ask me this. I actually did lose quite a bit of weight in high school, like 85 pounds, quite substantial. And that sparked my interest in it. But then more as I went into the sort of academics, there’s actually a single lecture I can remember back to where they taught us the concept of epigenetics. This is sort of the field of what regulates the genes that are expressed. And there’s actually little chemical tags that tag directly the DNA and also can tag the proteins that they wrap around. They’re called methyl groups. It’s just a carbon and three hydrogens. But those methyl groups, they regulate how tightly coiled the DNA is and whether genes can get turned on or off. And some of those methyl groups can come from the diet.

    And so it was just really intriguing to me at the time that diet is a source of this little chemical molecule that is getting added or removed from the DNA and turning on and off genes. And so you don’t really think about … We think about nutrition and chronic disease risk. This was just more like a very molecular question. When you change diet, what is happening to our DNA and how the genes are expressed? And so I’ve gone on and tried to do work in this general field of both how diet influences gene expression and how genetics influence nutrient requirements and how we respond to different diets.

    Thompson: And for better or worse, the question of “How does diet change who we are; how is diet foundational to human health?” this is clearly a question that is having a moment right now with RFK Jr., the Make America Healthy Again movement. There is surging interest in America’s diet and in ultra-processed foods and seed oils and sugar in particular. And I wanted to have you on the show because I followed your work for a bit, and you are just such a careful and nuanced communicator about the science and nutrition. I wanted to have you walk me through the actual nitty-gritty science of ultra-processed foods: seed oil, sugar, these sort of cardinal sins of the American diet as they’re represented in American media. So let’s start with a big-picture thesis statement here. It is a statistical fact that Americans have higher rates of obesity and chronic illness [than] other countries. And what I would like to know, for starters, is why. Has a scientific community reached anything like a consensus on this answer?

    Klatt: Yeah, it sounds like a simple question. And like most things in nutrition, simple questions just have many layers to them. But I think at a really high level, the laws of physics apply to human biology. Everyone accepts that there is an energy imbalance occurring where you have what we call positive energy balance, where our caloric intake is above our energy expenditure, and that is leading ultimately to rates of body weight gain.

    Thompson: So most basic consensus is that if people consistently eat more calories than they burn, the law of physics says weight goes up. How long has this been happening? How long has the rise in obesity been happening in America?

    Klatt: People will often pinpoint this to the 1980s. You see rates of obesity starting to really increase. But even going back further, we have spottier data before 1960s, but you can look at things like insurance records as well as military entrance academies. So this is all before we had nationalized surveillance data, but there seems to be a shifting kind of average BMI over time. So we’ve been in positive energy balance probably at a population level for quite a while. We just started at a much lower BMI, and it’s been shifting up and up and up. So you see in the ’80s is when we really start the population distribution shifting toward obesity, but we have had many changes to our food supply with industrialization, just from the availability of the calories to the things that we’re eating that ultimately have been driving positive energy balance—probably changes in physical activity or at least the amount of energy we expend in the type of work that we do.

    And so you can look across the past 150 years basically and come up with, everyone has a favorite pet hypothesis of, well, this changed in 1980, so therefore that probably explains the rates of weight gain afterward. You have small, little experimental studies that are often done saying, OK, just changing some aspect of food, whether it be a macronutrient like fat or carbs that people hear about or whether it’s something about the flavor profile, the texture. These things in controlled laboratory settings influence energy intake. And so we have no shortage of hypotheses. I would imagine it’s probably not one thing but many things kind of collected. [Everyone] has their favorite thing, like, this must explain it all. And in reality, there’s probably many, many, many small things that have combined to drive that positive energy balance that we’re seeing.

    This excerpt has been edited and condensed.

    Host: Derek Thompson
    Guest: Kevin Klatt
    Producer: Devon Baroldi