Hey there, it's Susan Peirce Thompson, and welcome to the Weekly Vlog. As you probably know, if you listen to this vlog, you almost surely know, processed foods are a huge problem.
There was a great study that came out a few years ago, showing that it's the processing of foods that's driving weight gain. What they did was they took a small number of people. It was a metabolic ward study, which is very expensive to do. They had people sequestered on a hospital ward floor. They couldn't go anywhere, and they fed these people very carefully controlled diets. They split people into two groups, equal numbers of men and women. They split people into two groups, and they fed one group an unprocessed foods diet and one group a processed foods diet. But the diets were matched for amount of sugar, amount of fiber, amount of fat, amount of protein, amount of carbohydrate. The diets were matched. It was just processed versus unprocessed.
And what they found was that people who ate the processed foods diet gained weight very rapidly, and the people who ate a whole foods diet didn't. As a matter of fact, they lost a little bit of weight. But then, they switched the people in the two groups. And then, the people who were now in the processed foods condition gained weight. And the people who had been eating processed foods, who are now eating whole foods, started easily losing that weight. None of these people had weight issues to start. The study really showed it's processed foods that are driving a lot of our issues.
So in 2009, researchers in Brazil came out with the NOVA, the NOVA Food Processing Classification System, to classify foods by their level of processing. Now, this is a great idea, super helpful. And with a classification system, you could start to, for example, say, "All right, we need school lunches to adhere to this sort of minimal benchmark of not being too processed."
I think current research shows that two thirds of the calories that kids and adolescents are eating are ultra processed foods. And oh, by the way, it was those researchers in Brazil who coined that term "ultra processed foods." That designation corresponds with the highest level of processing in the NOVA Classification System, which is level four.
So let me go through the levels of processing in the NOVA system. So level one is just whole real foods, so it's whole real foods or minimally altered foods. Level two is culinary ingredients, and then, level three is combinations of level one and level two, to make things like baked goods, bread, or also, complicated homemade dishes and things like that. Level four is ultra processed foods, so foods that don't really come directly from level one foods. So these are made of factory ingredients in an industrial plant, poured into bags and boxes. Ultra processed foods.
So this all sounds great, and since 2009, tons and tons and tons of studies have been published using the NOVA classification system. It's now gotten into widespread use. There are other systems for classifying the processing of foods, but this one is, by far, the most widespread. And I'm so in favor of this. I think it's really helpful. Unfortunately, unfortunately, a study just came out looking at the inter-rater reliability of experts trying to classify foods according to the NOVA system, and it's a mess. It's a mess, meaning it's not easy to tell what food goes in what category, at all.
The inter-rater reliability, on a scale from zero to one, with one being perfect correspondence, if person A puts this food into category three, other people are going to as well say, "Yes, this is a category three food." On a scale from zero to one, inter-rater reliability was around 0.32, which is painfully, excruciatingly low. Yes, everyone agreed an apple is an apple and an apple is a category one food, but as soon as you get beyond that, it's a mess. Oh, so this is problematic. This is problematic.
Let me tell you what these researchers did. These were researchers in Europe, and they recruit in France. They recruited a bunch of French experts, so these were nutritionists, these were healthcare professionals, who counsel people on their health and their food. These were food science experts. These were not laypeople. These were experts, and they gave them two lists of foods. One was a list of foods from the grocery store with their nutrition labels and ingredient lists, and the other was a list of generic foods without nutrition labels or ingredient lists. In both cases, there were over a hundred foods on each list, and they had over 150 experts assign these foods to categories.
Now, couple of things, the results were no better, no better, when they had access to the ingredients list and the nutritional profile, no better, which is problematic. It's like, even when you know exactly what's in the food, it's still hard to determine what category it should go in. Yeah.
So let me give you an example of a food that was incredibly spotty in terms of its categorization: plain yogurt. Now, some of the experts, I guess, noticed that plain yogurt is actually explicitly listed in the NOVA Classification System as an example of a category one food, so they put it in category one. But the non-alcoholic fermentation process, which is how you make yogurt, is explicitly listed as a category three process. So a lot of people put it in category three. To compound matters further, whey, casein, and lactose are explicitly listed as industrial ingredients that are only found in category four foods. So some people put plain yogurt in category four. Not exactly clear where plain yogurt should be in this categorization system.
Now, to make matters even worse, there was very low correspondence between these experts' assessment of a food's nutritional status and its category according to the NOVA system. Let me give you an example of why. A can of plain green beans, whole plain green beans in a can with some salt, that's a category three food, according to the NOVA system. Now, I eat a can of plain green beans. To me, that's a whole real food. That's category one, but because it's got some salt in it, and salt is category two, you combine that with green beans, and now, you've got a category three food, which, by definition, is a mixture of a category one and a category two food.
But Smucker's Grape Jelly, ultra processed grape jelly, would also be a category three food. You've got grapes and grape juice, and then, you're mixing it with sugar. Now, white sugar, ultra refined white sugar, is a category two food, according to NOVA. White sugar, white flour, both category two, those ingredients. As a matter of fact, they're the classic examples. Salt, sugar, oil, flour, those are the classic examples of what's listed as category two foods.
They call those "ingredients." So you mix sugar and grapes together, and you smoosh it all up and whatever. And you've got grape jelly, which is now a category three food.
We can all agree that a can of green beans is nowhere near grape jelly, in terms of nutritional value, nutritional impact. And so, very little correspondence between the category of the food and the nutritional status of the food. So all of this spells difficulty for the NOVA Classification System. Scientifically speaking, when you have a classification system, the first and foremost thing you've got to check is, how's inter-rater reliability? Meaning, how reliably can educated, informed people looking at that classification system put different items into their correct categories? Because you have to see. If you can't do that, the classification system is pretty well useless.
So I'm so sorry, NOVA system, but you're not helpful. That's not effective. That's not helpful.
So we're going to need something that is more helpful. But my prediction, unfortunately, is that I don't think it'll be developed, at least not anytime soon. I hope someone does develop something that would be an effective classification system of food processing, of the processing of foods. But the NOVA system is widely accepted already, and there's just so much ignorance and confusion about food in general these days, that I put the odds that a better system, that it gets proposed, that it gets accepted, that it gets widespread use, I put those odds very low.
So that's the state of the art, in terms of classifying foods according to their processing. I think one good thing that came out of this is we got the concept, the term, "ultra processed food." I think that's helpful. And as for the rest of it, figuring out, on some sort of hierarchy, which foods are more or less processed than others, we got a long way to go. It's sad but true.
That's the Weekly Vlog. I'll see you next week.
