Let’s start with a simple fact.

Cheetos are delicious. But while that heavenly blend of cornmeal,  vegetable oil, monosodium glutamate, and Yellow 6 might be hard to resist, it’s probably not making your body  as happy as it is your taste buds.

And that’s because Cheetos, Fritos,  Oreos, Jell-o, Spaghetti-os, and pretty much every other snack ending  in -o have been heavily processed. And from what we can tease  out of a bunch of messy data, that category of food appears  to be pretty bad for you. Which is a problem, because they make up… What number do you think I’m gonna say right now?

More than half. More than half  of the average American diet! But what is it about these ultraprocessed  foods that’s causing health problems?

As it turns out, the answer to that  question is way more complicated than the ingredient list on your  bag of cheese-flavored corn puffs. [♪ INTRO] One of the things that makes determining  the health risks of processed foods so sticky … and gooey and crunchy … is that it’s hard to define what  "processed" means in the first place. The first step is understanding all  the ways foods can be processed. Even something as simple  as chopping up a strawberry or roasting a potato counts as processing!

But processing includes lots of other things. You’be got pasteurization, canning, jerkifying... But generally, foods are categorized as minimally processed, processed, or ultraprocessed.

Minimally processed foods, or MPFs, are  just that: they are minimally processed. Not much has happened to them  between the farm and table. And what does happen to them tends to be a physical change rather than a chemical one.

Chopping and cooking food are  examples of minimal processing. So those sliced strawberries would count as MPFs. But many foods have been more than  minimally processed before they get to us.

Processed foods are those that have been  manipulated from what grows in nature, often using chemicals on top  of that physical processing. For example, bacon isn’t a pig. It  came from a pig, but it was sliced, cured, and treated with preservatives.

Similarly, a prepackaged smoothie  isn’t fruits and veggies. It probably includes fruits and veggies,  but they’ve been peeled, pulverized, preserved, and combined with other  ingredients like milk or yogurt. But if bacon comes from a pig  and smoothies come from fruit, where do Froot Loops come from?

Like Cheetos, they are an example  of ultraprocessed foods, or UPFs. This category also includes  stuff like “ready-made meals,” instant noodles, and candy. And let’s not forget ultraprocessed drinks  like Kool-Aid, soda, or energy drinks.

Preservatives, emulsifiers, and synthetic  dyes can figure heavily in UPFs. But while understanding what goes into  processed and ultraprocessed foods is one piece of the puzzle, understanding  why certain foods are processed can give us even more clarity on  how processing can affect food … and the bodies it goes into. Sometimes, processing can make food healthier.

Cooking and fermentation can make  certain foods more nutritious, because processing makes the nutrients accessible. For example, your body is going to be able to pull more vitamins from cooked asparagus than from raw. Processing can also make some foods safer.

Pasteurization and natural preservatives like salt allow food to travel longer  distances and stay shelf-stable. Freeze-drying increases shelf-life and  preserves nutrients and antioxidants. Also on the safety front, fermenting  stuff like milk and soy can make them less dangerous  for people who are allergic.

Polishing certain grains can  also reduce fungal toxins, making them safer for consumption. And sometimes nutrients are added  to processed foods to make them even better for you, a process  known as fortification. For example, sometimes Vitamin D is  added to milk, or iodine to salt.

Most of these examples would be  considered processed rather than ultraprocessed, thanks to  that end goal of maintaining as much nutritional value as possible. But the impetus for ultraprocessing...  is not quite so noble. UPFs are an incredibly lucrative  business for food companies.

To start with, they are cheaper to manufacture, mostly because synthetic ingredients  can be cheaper than natural ones. And because many UPFs don’t require refrigeration, they’re easier to transport and store as well. But to top this all off, they are very  popular with consumers, for a couple reasons.

They’re super convenient, for one thing. Many UPFs are ready-to-eat off the shelf, or just need a quick stint in the microwave. Much easier than cooking from scratch.

And grabbing a ready to go meal is often cheaper than purchasing ingredients and doing it yourself. Plus UPFs are really tasty,  thanks to added flavor enhancers. All that food coloring makes  them look tempting, too.

But ultraprocessed foods have a  pretty well-documented downside: they’re linked with a variety of health risks. But before we get into it, we  gotta take a quick ad break. This SciShow video is supported by ACT, the #1 taken college admissions  test in nearly half of U.

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To start, before we get into  the risks of eating UPFs, a reminder that correlation  doesn’t equal causation. So, even though we can see correlations  between eating UPFs and various negative health outcomes, there could  be other contributing factors here. Like, if I’m chowing down on some Cheetos  because I’m stressed out and don’t have time to prepare anything else, it  can be hard to tell if my raised blood pressure is due to stress, my snack  habit, or some other factor entirely.

It’s also tricky to determine whether  it’s actually the ultraprocessing that’s the problem, or high levels of  sugar, salt and saturated fats that these foods tend to have. But we can use meta-analyses to compare  lots of different studies on UPFs, pretty much all of which report certain  health risks associated with them. These meta-analyses of observational  studies have found correlations between UPF consumption and hypertension,  kidney disease, depression, anxiety, poor sleep, some cancers, premature aging, cardiovascular disease, type  2 diabetes, and obesity.

There’s also what appears to be an  association between UPFs and overall mortality … meaning the more UPFs you eat,  the more likely you are to literally die. The thing is, these studies can’t  answer how UPFs have these effects, and they can’t exclude  those confounding variables. For that you’d need controlled  conditions so you could run an experiment that strictly assesses UPFs vs  non-UPFs, no other variables.

Which we can’t do using humans,  so you know where this is going.   Yup, we’re gonna talk a bunch about rats. A study of UPF consumption  in young rats and mice showed it decreased bone density, slowed skeletal  growth, and led to fatty liver disease. In another study, UPF-fed  mice had higher weight gain, gut inflammation, and even  changes in brain metabolism.

And previous studies have  shown mice on a high fat, high sugar diet are more prone to diabetes, though it’s arguable whether this  is representative of UPFs per se. Rodent studies have also been used to  evaluate the effects of particular additives that UPFs often contain, and they found  that consumption of common emulsifiers led to gut inflammation,  higher rates of inflammatory bowel disease and disrupted the gut microbiome. In one study from Spain, researchers  fed the emulsifier to mouse moms during gestation and found  that it had negative effects on their offsprings’ cognition and metabolism.

And some specific color additives have been shown to be carcinogenic or toxic in mice. Of course, one thing we know for  sure is that rodents aren’t people, and their nutrition needs and  regular chow aren’t the same as ours, so the data shouldn’t be over-interpreted. Still, it’s data, and there’s  definitely unhealthy stuff in some UPFs.

But actually, it isn’t only the content of  these foods we should be worrying about, but also just the amount we’re consuming. Some people argue that UPFs  are literally addictive, meaning they cause compulsive  use, mood-altering effects. And we’re not just talking about  overeating because the food tastes so good thanks to all the added sugars and salts.

Addiction is a different level,  characterized by craving and loss of control. Studies on UPFs have found  changes in dopamine sensitivity and withdrawal symptoms related to  high consumption of these foods. If UPFs are truly addictive, it’s not  clear whether it’s a behavioral addiction, like gambling, or a substance-use disorder, like smoking, though scientists  are leaning towards the latter.

Exactly why this would be is still  a little bit of a mystery, though. It could be that they have less  fiber than whole foods and are easier for the gut to absorb, meaning  they hit your body faster and harder. But this is all still being investigated.

Either way, the seemingly addictive  nature of UPFs may have been deliberate. Both Kraft and General Foods, which are  large food suppliers responsible for UPFs such as Jell-O and Lunchables,  were once owned by Philip Morris. Yes, the same Philip Morris  that makes Marlboro Cigarettes.

The leaders of the company at the time  admitted to using the same techniques to promote addiction to foods  that they used for tobacco … things like enhancing flavor,  texture, and visual appeal. So maybe it’s not so much  of a surprise that it can be hard to eat ultraprocessed food in moderation! As I mentioned, the average  US consumer gets more than half of their daily calories from  them, according to a 2010 study.

And that trend seems to be only increasing. All that said, you don’t necessarily  have to chuck your vending machine Cheetos straight into the  trash to live a healthy life. There is so much more that is left  to be studied when it comes to UPFs.

We need more research to know exactly  what is behind these correlations. Not to mention the fact that I’m  not a doctor or a food scientist, so you should always consult your  real doctor for advice on your health, and take all of this with a grain of salt. But not too much salt.

And not mixed  with sugar and fat. That is not ideal. So, definitely, it is smart to be mindful  about how many UPFs you’re eating.

And where you can, it’s a good idea  to take the path of less processed. But, of course, we’re not here to shame  you for your love of breakfast cereal, boxed mac and cheese, ramen noodles, or any of those other tasty and convenient UPFs. The most important thing when you  grab a bite to eat is to be informed, so you can make conscious decisions, because knowledge is sweeter than  anything you’ll find in the snack aisle. [♪ OUTRO]