>Satiety is a mental construct.

Yeah, just not according to science.

E.g. there's ghrelin, cholecystokinin and other "satiety signals".

Except if you mean "satiefy is a mental construct" the same way pain is a mental construct. In which case, in a Kantian way, everything is, including space and time.

>What your brain tells you to put in your stomach is almost entirely divorced from nutritional requirements for thriving and surviving.

(a) You'd be surprised.

(b) It only appears that way because we have diverged in a exteremely small span of time (evolutionary speaking) into completely different circumstances and food availability.

Otherwise, what the brain tells us is very much based on nutritional requirements for thriving and surviving.

It's just that in 2022 we have an endless supply of food we can just order or walk into a supermarket and buy, as opposed to food scarcity where we don't know if we will be able to find something to hunt tomorrow - like the last 100,000 of thousands of years before historical times (and millions of years considering our primate ancestors)...

Hormones are input signals to a neural network that produces a sensation of hunger as an output. The mapping of the network can obviate those inputs easily.

>not according to THE SCIENCE

sorry, dont care

Science, like reality, is that that doesn't stop existing when you close your eyes (or when you don't care).

did the sciences of phrenology, plum pudding model, God doesn't play dice, et al stop existing? I hope?

You seem to conflate science with individual theories (which can be abandoned, expanded, improved, or kept as a special case approximation, like Newtonian physics, and so on), and advances in knowledge.

You also seem to think that the prevailig theory at some era is intechangable with arbitrary personal opinions about how things are.

This is bro science. Sorry dude. Caloric intake matter because in the end it is CICO. However, there are foods that absolutely make you feel full quicker and for a longer period of time and that matters as much as calories because if you can't fight off the hunger because your diet is primarily white bread and doritos as opposed to healthy fats , greens, and proteins then calories won't matter because you will 100% fail because of cravings.

It could be much much more than CICO. If you want to read an epic saga on modern obesity and it's theories check out

https://slimemoldtimemold.com/2021/07/07/a-chemical-hunger-p...

It seems like everything in that article reinforces CICO. Is there something that diverges from the CICO model that I might be missing?

E.G. it’s examples of the Maasai and Inuit eating higher calories make a lot of sense when you consider their exposure to temp extremes and additional cal burn coming from thermoregulation (along with probably elevated levels of daily activity).

Most of the nuance I’ve seen around CICO that holds isn’t that CICO isn’t true, it’s that the intake and output are hard to calculate when you look at nutrient absorption and lifestyle

CICO may be scientifically valid but it's useless in practical terms. People who tend to be constipated absorb much more energy from their food and those with fast digestive tracts absorb much less. Everyone is somewhere on that spectrum, so, from person to person, you would never have a practical way to assess what the CI or the CO is in the CICO model.

Au contraire, it's very useful. If you want someone to lose weight, calculate their BMR + their rough activity based cal burn, and give 'em a 15% deficit. They'll lose weight. Not just water and glycogen. They will burn fat.

If you want someone to gain weight, do the same calc, tell 'em to eat 100 more calories. Not gaining? 200. Really not gaining? Wow, fast metabolism, shock 'em with 500 extra. Anecdata, but the only time I saw someone not slowly gain on 200 extra, there ended up being a lot of walking we weren't accounting for in our maintenance cal calculation. Our O in CICO was off. For reference, 200 cals is like a 16 oz of coke, or 2-3 apples. Decently precise.

The variance between a fast and slow metabolizer isn't 20% of daily calorie burn, maybe 10% on the high end. Guesstimation, probably more like 5%. Well within the tolerances that are used for weight modulation (up or down).

If it weren't the case, why are so many body builders (natty or enhanced) able to run repeated bulking and cutting cycles? Are they genetic outliers?

Can you calculate it 100%? Nope -- so many variables, probably tons we don't even know about yet. But it's accurate enough to be very effective, and very simple to implement.

Mark Pimentel's lab which studies disorders of the gut has hypothesized that people with extremely slow transit times can absorb 2-3x the amount of energy from food in comparison to people with regular transit times. I think there is a high amount of variability; and importantly in the context of losing weight, people who are overweight often have slow intestinal transit due to their dysregulated gut microflora.

I'm sort of with you, but it sounds more to me like: start eating less, and you'll lose weight; eat more, and you'll gain weight. There's just too many variables here that change how food is metabolized and digested; including the microbiome which CICO ignores.

You got a source for that study? A cursory google didn’t reveal anything and 2-3x is suspect. To your second point, wouldn’t the microbiome (and slow digestion) just be another input into CICO?

is it just caloric absorption, or are various essential nutrients also absorbed more and less? asking because coffee can speed up my transit time dramatically, and I'm always down for cutting calories!

AFAIK this has not been studied, but I would assume that nutrient absorption could feasibly vary with motility speed just like energy absorption. For example people with chronic diarrhea are usually deficient in several B vitamins especially B12, although their poor absorption may not be only due to rapid transit time and could stem from other gut issues. Rapid transit time is certainly a factor though.

I don't count calories and I will never start counting calories. Hence it is useless.

you are ignoring what he said. I don't know if it's true, but he's saying CI is not simply a function of how much you put in your mouth, but how much of that your body absorbs.

the other answers here are more detailed, I just wanted to state it simply.

Not ignoring it - the in in calories in isn’t what you put in your mouth, it’s what you can absorb. Hence why you don’t count fiber towards your calories.

Again, the digestion point seems to reinforce CICO. If you gain weight because your digestion is slower (let’s grant the point), it’s not because your body some how treats calories differently, it’s that you’re getting more calories from your food. Your calories in are higher.

Not to mention that diet products have existed to game your digestive system to absorb less calories from your food. With the rationale being… less CI in CICO. See also: folks abusing laxatives for this purpose

I also say, to whatever readers may care, the reason I belabor this point so much is that obesity related health issues have a massive effect on QOL, public health and personal mental health. I say this having grown up in the southern US, having obese family, having my own fitness / weight loss problems, having seen gangrene diabetic foots with my own eyes. I know vividly what it looks like for someone you love to be heavy, miserable specifically because theyre heavy, and totally hopeless that “they just can’t lose the weight”.

Throwing information out like this (w/o source and at best poorly replicated), that CICO is useless because of digestion rate, is incredibly dangerous because it falsely legitimizes that hopelessness. It traps people. And it maybe only applies in <1% of cases, where you have not just obesity but also compounding, very specific digestive issues. The opposite is also true — you don’t just drink coffee to knock off enough cal absorption to make a diff — you take laxatives you don’t need and have extremely abnormal, frequent BMs.

Anyone and everyone can lose the weight. It’s just CICO. You gotta figure out your input and output to account for the minor individual variances, and lock in a lifestyle to do it. But it’s just CICO at the end of the day.

CICO is axiomatically true, but the problem is CI is easy to measure and CO isn't.

Different people use different amounts of calories to do the same things (including sitting around), and different people extract different amount of calories from the input. Some people can extract calories from PF Chang or Buca di Beppo, but not me. Weight control by eating foods that go straight through sounds terrible though.

The problem is that the body and brain operate a complex control loop whose sole purpose is to regulate calories in and calories out.

You can run an additional control loop mentally but what purpose does that serve? Reducing caloric intake while your body screams increase caloric intake is very difficult. You should instead use the control loop you already have.

>this is bro science

sorry, I don't care

>Satiety is a mental construct.

Are you implying that there aren't physical manifestations that cause hunger? In other words, I could inject you with a suprahuman amount of ghrelin and you wouldn't feel hungry?

There are physical situations that can nudge your brain's choice to make you feel hungry or not, IME. For example, I stopped eating breakfast and lunch for two years (because, I am a colossal idiot, and knew it was stupid when I did it) and it took very little time for my body to realize "feeling hungry" at noon was a fools errand, so it quickly stopped happening. I was absolutely physically hungry, seeing as I wasn't eating larger dinners, and having been about 18 hours since I last put food in my body, but habit has a large effect on your feelings of hunger if you aren't living in the wild Savannah. If my thoughts are correct, then a possible indicator would be people with wildly different "normal" times for dinner would get hungry at those different times, ie my grandparents who eat at 4 get hungry at 4 compared to someone who normally eats at 8pm getting hungry at 8pm.

I'm unsure if that "support" for my argument exists.

That fits with my current understanding. Your body's hunger response (driven in part by hormones) is complicated, and for lack of a better word it can be "habituated" to a routine. But I believe there are still very real mechanisms (like said hormones) rather than being a psychological construct. I would be willing to bet if you had blood samples, you would see very real distinctions in blood markers associated with hunger as your response changed.

This leads into the very real feedback loop between hormones and psychology. Addiction is a classic example. Both chemical and psychological addiction are real. It's basically impossible to break an addiction without tackling both

I've never managed "underweight", but having been as high as 320+lbs and as low as 161lbs, I agree. The key to losing weight is to find ways to ignore what your brain tells you to eat and stick to a calorie intake limit that matches the base metabolic rate of your target weight.

If you mean "mental" as in "not based on reality", then no, that's wrong.

However, it is true that your hunger urges are not solely based on thriving and surviving, but also significantly on the current state of your gut bacteria, which is highly influenced by diet and stress. They say the gut is a second brain for good reason.

In some sense, pain is also a mental construct — just some electrons bouncing around in one's brain, yet it feels very much real.