It has been shown that any group of people that starts to adopt a more American diet more heavily will see increases in rates of obesity.

> when they eat an average American diet

That site does control for diet. E.g., my Korean-born wife has always had home-cooked Korean food growing up in North America.

Exactly. If you are eating chips it’s very hard to stop until the pack is over.

There are 3 options in order of effort: eat the next snack from a pack in your hand, decide and stop eating the cookie that is in the pack; get another pack to continue eating.

It requires more effort to get another pack and that biases towards the “stop eating” outcome. If packages are large the the easiest action is continue eating.

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.

And chewing. How fast it is eaten is likely affected.

> 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%

Similar to “The Milkshake Study”

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 suppose it's partly because it's the whole meal that is being represented and they match it for nutrients.

I'd guess they wanted to include store purchased bread, hence the pb&j.

The other thought i had was that most peanut butter includes (at least) palm oil (ultra processed) and sometimes other emulsifiers to prevent separation. Though you can buy pb that is just peanut and salt.

The jelly would contain quite a bit more in the way of preservatives, regulators and flavour enhancers etc than the jelly i'd make at home (if i did such a thing)

I'd guess it's just regular cheese which does require quite some processing to make but unless it's got extra additives to extend shelf life, change texture or taste it's just processed.

Peanut butter definitely is. Even if you make it home-made you need to add some sort of oil to get the persistent creamy texture, but it naturally separates. To get that permanent creaminess you get from the store it's going to have various sorts of chemical additives - emulsifiers, stabilizers, etc. You also generally want to add some sort of a sweetener. I use honey, but with store bought stuff you're looking at all sorts of stuff including e.g. high fructose corn syrup.

By contrast cheese is completely natural outside of a few exceptions like American cheese. You take milk, add something to curdle it like an acid (e.g. vinegar) or rennet - an enzyme obtained from the stomach of young calves, separate the coagulated stuff, salt it, dry it, age it - you now have cheese. Ricotta can even be made straight from raw milk with no additives. Cheese's long shelf life is natural.

Probably it is the bread which classifies it as UPF.

Group 4 considers the packaging the food comes in - "sophisticated packaging, usually with synthetic materials."

Wtf. Thanks for sharing.

For the purposes of this conversation - let’s think of it as pre chewed food.

The body evolved to eat foods that take a lot of chewing and digesting. As far as I can tell, one of the biggest problems with food that is “too” processed is that it’s absorbed far too quickly and early in the tract.

Food that makes it all the way through has a slower and more even absorption rate so we don’t get hungry again as fast.

And? For an "average cheddar" you still have to heat the milk, add enzymes, and age it and at the end you get something entirely different. Sounds like "processing" to me, or to use your words, "industrial reformulation."