Why does it persist? Well, as I suggested before, industry loves it. It’s a great way to sell food. And best of all, it gives an advantage to the processed foods, because processed foods can be re-engineered to reflect the latest nutritional understanding. So when the low-carb craze hit, and carbs were suddenly evil, if you were selling processed food, you could just re-engineer it and you could make low-carb pasta. Low-carb bread. Whereas whole foods like avocados, to take an example of a food that’s gone in and out of favor, can’t change their nutritional stripes. So when fat is the great evil, avocados are out, they are fatty. But when mono-unsaturated fats are in, the avocado is redeemed (laughter).

So, you see, it gives an enormous edge to processed food, and that is where the money is made in food in America today. The more you process food, the more profitable it is.

It also so happens that the more you process food the less nutritious it is. But we cover that up with the sheen of nutritionist research.

Also, I think, nutritionism fits really well with a food and agriculture based on monocultures of a couple very simple grains. Because all our processed food is essentially made from cheap subsidized corn and soy. If you take those basic sources of starch in corn and protein in soy, fat in soy and corn, and you kind of tease it apart and put it back together and that’s what our processed food is.

So the way you make money is by taking a simple raw ingredient, processing it a lot, and engineering it to reflect the latest nutritional wisdom. And we’ve got just the perfect ideology to go with that kind of agriculture. So that is one of the links between our agriculture and our thinking about food.

Now nutritionism did arise to solve a real problem. There is a problem with the Western diet. And now I’m going to talk about what we do know about food and health. Because in a way, it’s all we need to know, but it’s hard to deal with for foodies.

This is the elephant in the room: the Western Diet. What is it? Well, it’s the way most of us are eating. The way humans have eaten has changed more in 140 years than in the 10,000 years before. And it changes with the processing of grain, the refining of oils from grain, the arrival of free sugar and high fructose corn syrup, lots of processed food and less reliance on whole foods — fruits, vegetables, whole grains. That, in short, is the Western diet.

And there are some key events. One is the invention of the rolling mill in the 1860s, which allowed us to refine flour and get white flour, and then the sugar trade that begins in the Caribbean. Here’s what we know: People who eat this way and people who begin eating this way, pretty reliably get a set of chronic diseases.

This was first observed around the turn of the last century. Mostly British and some American health workers, working in the colonies, watched as this kind of food was introduced to cultures that had never eaten this stuff. They had eaten a traditional diet, meat or vegetables, but did not have refined flour, sugar, these refined oils.

And they watched what happened. They called it the store food or the Western diet and these doctors working in clinics began to see, for the first time, heart disease; for the first time, Type II diabetes; this group of cancers related to this diet, which is not just digestive-system cancer, it includes breast cancer and others, but are thought to be related to diet. And stroke, also.

And they made this connection: They said the Western diet is here and these are called Western diseases. And this has been understood. We don’t talk about it much anymore because it’s one of those big obvious facts, but the whole debate over nutrition that has unfolded since then is essentially an attempt to find a causal mechanism — what about the Western diet leads to those diseases? Is it the fat? Is it the protein? Is it the carbohydrates?

And the reason we want to know that is because we’re good productive scientists, and we really want to know what’s responsible — and if we can figure it out, we don’t have to change everything. We can just prune — we can just get off the saturated fat or trans fats, whatever.

And the other thing we know that’s really interesting is that these traditional diets that people had before the Western diet were incredibly diverse. You have Maasai tribes in Africa subsisting on meat, milk, cattle blood and nothing else. You have Inuit in Greenland subsisting on whale blubber and some lichens. You have Central Americans subsisting essentially on corn and beans. You have this incredible diversity of traditional diets.

And that tells us that there is no ideal human diet, that one of our great good fortunes is that we can do well on whatever nature has to offer in the six of the seven continents where we found ourselves. So there is no one proper way of eating. There is, however, one way not to eat.

And this is the amazing fact: How could, given so many different healthy ways to eat, how could civilization, 10,000 years after the birth of agriculture, have come up the one way that reliably makes people sick? (Laughter.) This seems to be where we find ourselves. We have created a diet that makes us sick.

So where does that leave us? Well, I think it leaves us at this very interesting fork in the road when it comes to food. We can surrender to the Western diet and wait for evolution to accustom us to it. This will happen. It is happening now. We are selecting for people who can endure huge spikes of insulin from huge spikes of glucose in the bloodstream; lots of processed meat; all the things we’re eating. We are selecting people who can endure it.

And that’s one of the reasons, possibly, that we see some populations getting sicker on this diet than others. Those of us descended from Western Europeans have been eating refined sugar for longer than immigrant cultures that have just come to this country and been exposed to fast-food culture for the first time. They have much more trouble. Is it genetic or not? We don’t know really know, but there is a process of acclimatization going on.

The problem with this approach, though, is that it’s going to be really expensive. We’re going to have to spend a fortune on dialysis. We’re going to have to spend a fortune on heart bypasses. This is what getting used to this Western diet means. The Centers for Disease Control predict that one in three Americans born in the year 2000 will suffer from type II diabetes. That is just stunning.

Right now it’s 7 percent of the population and it’s rising quickly. You know, it used to be called adult onset diabetes, but it started showing up in children so they had to change the name. And what kind of sentence is that? Well, it’s 14 years off your life. It’s $12,000 or $14,000 in extra medical expense. It’s cost of amputation, it’s the cost of blindness. It’s a serious sentence, so getting used to this diet is going to involve a lot of pain and a lot of expense.

It is a future in which we have dialysis centers on every street corner in the inner city, right next to the check-cashing store. You see those cropping up already. It is a future where diabetes is a lifestyle, and indeed you see diabetes magazines, Diabetic Living, by the checkout counter. These are all signs of a culture trying to normalize this condition that, by the way, can be prevented with a change in lifestyle. So that is one road — make no mistake about it, that is the road we’re on.

The other road is to change the way we eat, and get off the Western diet. And that seems to me the simpler and more beautiful solution. And how do you do it? Well, it’s easier said than done, obviously. This Western diet is really cheap and abundant and accessible for almost everybody. And eating healthier costs more money and still is not accessible to everybody.