> The non-UPF and UPF test meals were closely matched on meal weight, energy, energy density, macronutrients, available carbohydrate, glycaemic index and load, total dietary fibre, sodium and water (all ≤1.6% deviation between meals; Fig. 1b).
So they did match glycemic index, which the article omits.
I was about to comment that the physical structure of the food and the fiber content also make a difference. For instance, rolled oats are available in different thicknesses, and the thicker ones don’t digest as easily. Brown vs white rice is another example.
But these examples have different glycemic indexes, which the study matched for.
Not only psychology, but training. If your body gets a load of sugar every time it tastes UPF additives, it learns to release insulin on taste to protect itself.
Another option is that it's affected by the order of consumption.
I know somebody who got really into blood glucose monitoring, and she tells me that the order in which she eats a meal affects how much it spikes her glucose. So if she eats a piece of toast followed by a piece of cheese, it causes her a bigger glucose spike than she'd get if she eats the cheese first and then the toast.
Looking at the two meals in the study: if I sat down to eat the processed one, I'd probably start with the veggie straws. If I saw down to eat the unprocessed one, I'd almost certainly start with the egg or the cheese.
edit: and here are some other options: I notice that the unprocessed one is grain-free, vegetarian and has significantly less sucrose. I don't know if any of that makes it more or less healthy, but they're significant differences nutritionally.
> I know somebody who got really into blood glucose monitoring, and she tells me that the order in which she eats a meal affects how much it spikes her glucose. So if she eats a piece of toast followed by a piece of cheese, it causes her a bigger glucose spike than she'd get if she eats the cheese first and then the toast.
This is what I read in a book about glucose. So I went ahead and measured. I found it not true, at least in my case. The recommendations of eating salad before your meal do nothing measureable for my glucose spikes.
If you look up how to calculate the glycemic index of a meal, the formula treats each meal component's glycemic index as a proportion of the total meal's glycemic index.
But the above example shows that the body doesn't treat food in that manner - the relatively low carb, higher fat cheese didn't smooth out the higher proportion carb count of the toast.
In the paper, the largest carbs for the ultraprocessed meal was instant mashed potatoes, while the non-processed meal had bananas as the largest carb source followed by craisins/cranberries.
The high carb foods in the unprocessed meal are paired with fiber.
The high carb foods in the ultraprocessed meal are NOT paired with fiber.
The fiber slows the rate of carb intake.
Same thing occurs with protein - same amount of ground beef and steak, ground beef meal will result in faster amino acid ingestion than the steak meal. No idea if there are any pros/cons of the faster ground beef ingestion, but there is a difference in how the digestive system processes the two meals.
Before we come to a final conclusion on this, we need to reexamine the NOVA food classification system. It holds some rather baffling contradictions. For instance, if you buy a deep fryer and a mandolin slicer to make your own potato chips at home, they're classified as processed foods. But if you buy a bag of plain potato chips (ingredients: potatoes, oil, salt) they're classified as ultra-processed.
They matched water content between the meals, so I guess only the ultra processed one required additional water to match the natural water content of the less processed one.
This is a good question but not an invalidation of the study. People underestimate the cost of doing large scale surveys, first year researchers become painfully aware of it. There are lots of research were you try to get a quantitative result cheap. But most costs a lot of money (the big studies are usually very well spent money imho)
From the actual study:
> The non-UPF and UPF test meals were closely matched on meal weight, energy, energy density, macronutrients, available carbohydrate, glycaemic index and load, total dietary fibre, sodium and water (all ≤1.6% deviation between meals; Fig. 1b).
So they did match glycemic index, which the article omits.
That means the only options left are micronutrients, specific additives or psychology.
I bet a lot of this is psychosomatic, you expect some food will give you fast energy so your body thinks that means you need it and releases insulin.
I was about to comment that the physical structure of the food and the fiber content also make a difference. For instance, rolled oats are available in different thicknesses, and the thicker ones don’t digest as easily. Brown vs white rice is another example.
But these examples have different glycemic indexes, which the study matched for.
Not only psychology, but training. If your body gets a load of sugar every time it tastes UPF additives, it learns to release insulin on taste to protect itself.
Isn't that what glycemic index means though? How quickly the sugar gets released?
> That means the only options left are
plus all of the options that are complete unknowns which, in biology, is probably close to 99.999%
Another option is that it's affected by the order of consumption.
I know somebody who got really into blood glucose monitoring, and she tells me that the order in which she eats a meal affects how much it spikes her glucose. So if she eats a piece of toast followed by a piece of cheese, it causes her a bigger glucose spike than she'd get if she eats the cheese first and then the toast.
Looking at the two meals in the study: if I sat down to eat the processed one, I'd probably start with the veggie straws. If I saw down to eat the unprocessed one, I'd almost certainly start with the egg or the cheese.
edit: and here are some other options: I notice that the unprocessed one is grain-free, vegetarian and has significantly less sucrose. I don't know if any of that makes it more or less healthy, but they're significant differences nutritionally.
This is the main thing of Jessie Inchauspé. One of her many videos on the subject: https://www.youtube.com/watch?v=HEEUrIQ_3O4
> I know somebody who got really into blood glucose monitoring, and she tells me that the order in which she eats a meal affects how much it spikes her glucose. So if she eats a piece of toast followed by a piece of cheese, it causes her a bigger glucose spike than she'd get if she eats the cheese first and then the toast.
This is what I read in a book about glucose. So I went ahead and measured. I found it not true, at least in my case. The recommendations of eating salad before your meal do nothing measureable for my glucose spikes.
If you look up how to calculate the glycemic index of a meal, the formula treats each meal component's glycemic index as a proportion of the total meal's glycemic index.
But the above example shows that the body doesn't treat food in that manner - the relatively low carb, higher fat cheese didn't smooth out the higher proportion carb count of the toast.
In the paper, the largest carbs for the ultraprocessed meal was instant mashed potatoes, while the non-processed meal had bananas as the largest carb source followed by craisins/cranberries.
The high carb foods in the unprocessed meal are paired with fiber.
The high carb foods in the ultraprocessed meal are NOT paired with fiber.
The fiber slows the rate of carb intake.
Same thing occurs with protein - same amount of ground beef and steak, ground beef meal will result in faster amino acid ingestion than the steak meal. No idea if there are any pros/cons of the faster ground beef ingestion, but there is a difference in how the digestive system processes the two meals.
Before we come to a final conclusion on this, we need to reexamine the NOVA food classification system. It holds some rather baffling contradictions. For instance, if you buy a deep fryer and a mandolin slicer to make your own potato chips at home, they're classified as processed foods. But if you buy a bag of plain potato chips (ingredients: potatoes, oil, salt) they're classified as ultra-processed.
Make your own pastas with good quality flour and prepare a serve the same size as what you would normally be having with pastas from the supermarket.
It's very likely you're not going to finish your plate.
Why is cheese not considered ultra processed?
Would love to read the original research paper if anyone has access to it. My university unfortunately doesn’t.
It's linked right at the bottom of the article and you can download the full pdf.
https://www.nature.com/articles/s42255-026-01619-4
Only includes water in one type of meal?
They matched water content between the meals, so I guess only the ultra processed one required additional water to match the natural water content of the less processed one.
I believe they are on to something, but wouldn't it be much better if the sample size was larger than just 57 people?
This is a good question but not an invalidation of the study. People underestimate the cost of doing large scale surveys, first year researchers become painfully aware of it. There are lots of research were you try to get a quantitative result cheap. But most costs a lot of money (the big studies are usually very well spent money imho)
Example: five years, 10000 participants, $170 million https://www.nih.gov/news-events/news-releases/nih-awards-170...
Of course but I'm sure they made the sample size as large as their funding permitted and it's better than nothing.
Larger sample sizes allow you to detect smaller effects. Since a signal was seen here effect size doesn’t seem to be the problem.