Modern processed foods have very little fiber and other non-processed parts, making you full slower causing you to overeat. A glass of coke has 140 calories, and so has 2-3 apples. You'll stop eating after 3 apples but can easily have 2 glasses of coke.
The above also causes blood sugar to spike drastically immediately after eating processed foods, causing you to create a high amount of insulin, drastically lowering blood sugar and creating fat. Low blood sugar then causes you to become hungry soon after. This is the famous "hungry 2 hours after eating McDonalds" efffect. Non-processed foods are digested much more gradual.
The calories are more empty. Lots of sugar and fat, not much protein and micro-nutrients like minerals and vitamins.
They are made so you can't stop eating them, e.g. bliss point [1]. They hack our reward centers to so it feels so good to eat you'll overeat. You wouldn't eat 20 sugar cubes in one sitting but will eat a tub of Ben and Jerry's.
Every time someone repeats this sort of thing I have to laugh to myself a little. If only it were so easy to keep my body from constantly craving more calories!
Try protein shakes. Or other high-protein foods.
But if you've made your body accustomed to a diet high in simple carbs (esp sugars), you need to break that cycle as well.
It is very irksome to me when people try to hand out nutrition advice on the internet like they know goddamned anything about it. I successfully lost over 150lbs and I never found a solution to not craving food constantly.
I can cook a meal and freeze it for a while reheat it and enjoy it - to allow it to survive (with a decent taste) long bouts of freezer burn and going stale I need to load that sucker up with a bunch of salt and sugar so that I don't care that the food tastes like cardboard.
I can't speak to any molecular effects - those may also exist - but most of why processed food is bad for you is just to make it taste really really good so you'll come back for more - even if you're not hungry! Yay obesity!
I imagine at some point in the future folks are going to look at the diet of the late 20th century like we look at covering your baby's crib with lead based paint.
There is a lot more than flavour and preservatives in processed food.
The difference in texture
The refined sugars in processed are nothing like natural sugars in raw food
Industrially hydrogenated fats are not the same as naturally hydrogenated fats (margarine is not coconut oil)
Additionally there are the traces of the machines used in the processing. The chemicals that make the plastic hoses soft (who's name escapes me) are coming under scrutiny now for being very bad for us.
Not a nutritionist, but I believe the answer falls into two broad categories.
One, chemical: processed foods frequently contain additives, e.g. preservatives, that less-processed food doesn't.
Two, physical: a peach smoothie is digested and hits your bloodstream differently from a whole peach. They're chemically identical but physically different, and that changes everything from how quickly you ingest it, how much of it you ingest, how it hits the stomach and how it hits your gut.
Back to the additives, what difference does it make if your body properly disposes of it because it can't break it down and it doesn't get absorbed by you? Or...does it get absorbed by you (which is what I'm partially asking)?
I think that eating a peach smoothie, one where you just take a peach and some ice - throw them in a blender and mix away, is no different from eating a peach[1] but ordering a peach smoothie at Jugo Juice is not peach in a glass, it's some peach and added juice (containing added sugar) and added sugar also some ice, probably with added sugar - all mixed together with some "healthy protein base" which is probably a bit of whey with added sugar - basically a smoothie ends up having very little relationship to the fruit.
Additionally if you slurrify raspberries you can drink them by the dozen in a single gulp - while eating them by hand you'll strike a more leisurely pace and stop once you're feeling full - often times with smoothies and the like we'll over consume because it takes a while for our body to actually realize we're full.
1. Maybe a slight loss of healthy stuff due to fibers separating out and not ending up in the juice but ideally that's negligible.
Your body has regular teeth. Most people don't chew even 30 times per bite.
A blender has mega-ultra-turbo teeth that are both way, way sharper than a person's and also they never get tired because they're powered by electricity not muscles.
How much chewing do you think is equivalent to blending? My very unscientific guess is that blending is something like 1000 chews per bite or more given that our teeth aren't as sharp as blender blades.
Eventually quantitative differences (number of chews) become qualitative (sugars and starches encapsulated in small bits vs chemically liberated). Blenders do a lot of the work of digestion mechanically well before your body has a chance to do it chemically.
Extracting energy and nutrients from food is highly optimized by evolution for obvious reasons, even in the case of omnivores such as ourselves. Modern "ultraprocessed" food is not adaptive.
A smoothie vs a peach may well have different glycemic indices. Few people chew their few up to the extent that a bender will break it down. Also, how many peaches go into a smoothie, and how much extra sugar via, say, yogurt, or smoothie mix?
if you juiced one peach you get the calories of one peach minus the non juice components. which I'd estimate to be approx 100mls
if you drink a peach smoothie you consume the juices of many peaches minus the non juice components.
I am also not a nutritionist, but from my reading processed foods are bad because (1) they just have far fewer nutrients, vitamins and minerals that our body needs to function, (2) the additives and chemicals that are added sometimes harm our body directly and/or require the body to dedicate resources towards removing, or (3) they harm our microbiome by feeding bad bacteria which similarly produce stuff that isn't good for your body and damaging the good bacteria which we need.
Faster absorption means higher peak serum glucose levels and higher amounts of insulin released. More insulin translates into more promotion of insulin resistance. IIRC, high serum glucose is also not good for your arterial lining.
Increasing the number of masticatory cycles is associated with reduced appetite and altered postprandial plasma concentrations of gut hormones, insulin and glucose [0]
[0]https://www.cambridge.org/core/services/aop-cambridge-core/c...
TL;DR It's not just about calories, it's about what the food makes you do later.
However, fiber lowers cholesterol levels by preventing cholesterol from being absorbed, and slows the absorption of glucose. When we examine the modulating effects of ingredients and couple that to biological non-linearities, it's not too hard to see how processing can affect how food interacts with the body. Reduced fiber foods, can affect the body in ways different from non-processed food even if the molecules being ingested are identical to those in the original ingredients.
> high-fat, high-sugar, high-salt diets
Much like how the attention industry has refined advertisements, games, news, etc to become exceedingly effective at targeting the pleasure areas of the brain, making us want to consume more, so too has the food industry.
Humans have evolved to find pleasure in eating fat, sugar, and salt, as the former are excellent sources of energy, and the latter is required by many processes ("Brawndo, it's got what plants crave!"). Processed food has optimized, distilled, and combined these components into foods that could never be found in nature, and which our bodies are ill-equipped for.
In last 100 years we started adding lot of chemicals to our food without knowing what long term effects they produce. Thats why fortified bread is not same as whole wheat bread.
Maybe in future we will make the ideal food in a lab or our gut will get adapted to process highly processed food.
I'm under the impression that when I eat food, my stomach converts it to a liquid, which then gets further "processed" through my digestive system, eventually absorbed in my blood stream. Is it the residual stuff that my body cannot break down but was unable to convert to fecal matter along the way that feeds into my blood stream the bad thing? Or is it still just straight up ignorance because people are afraid of having yet another process abstracted from their daily lives?