All models are wrong, some are useful.

CICO is neither a religion nor a complete explanation of metabolism. It’s a super simplified model that leads to some useful practical conslusions (eg it’s easier to eat less to lose weight than exercise more, some foods will make you more fat than others relative to how full they make you feel).

It’s super accessible, you can look up the calories of whatever you eat and whatever exercise you do.

I’ve seen lots of valid complaints about CICO, but never a suggestion for an alternative that’s similarly useful with even the same magnitude of simplicity.

Note I take CICO to mean bio-available calories roughly equals base metabolic rate plus exercise out for the average person. Actual energy-balance “draw a box around a person” joules in equals joules out is unhelpfully reductionist.

Calories in calories out is unfalsifiable so people hide behind it as if it makes them invulnerable.

If people don't or can't measure CI or CO then you can blame them for being wrong. All of this flies in the face of the fact that your body should be able to regulate this for you, which would make manual calorie counting in your head or via apps obsolete.

So there are only two possibilities left. Either our bodies are defective and we need crutches like machine assisted calorie counting or our bodies work just fine but there are some weaknesses that can be exploited and calorie counting is just a technique for defending against those who exploit them.

And no I don't mean there is an evil conspiracy by the food industry. Your obese parents telling you to eat two pizza per day can be equally exploitative because listening to parents' orders is higher priority than listening to what your body says about how many calories you have consumed.

> a suggestion for an alternative that’s similarly useful with even the same magnitude of simplicity.

To me the issues comes down to how people deal with the simplicity: when we’re told we don’t have to think hard and focus on reading numbers on a label, it’s comforting enough to not want to get back to the cold hard truth. Even when it doesn’t work, it’s just simpler to blame people (including us) than to try to think hard again.

People hate disclaimers and caveats. You can provide as many disclaimers and caveats as you want with the ultra simple theory, they will be forgotten instantly, only the simple part will remain, evolve on its own and live its life as a meme.

I’m with you that it should be fine if it’s a net positive for the vast majority of people. But it’s now the prevalent advice, and looking the stats it doesn’t seem to have a positive effect. If anything, we now know the meme advice doesn’t work for most people.

I've never seen poop included in the "calories in, calories out" diet talk, which seems strange. The argument for it is it's a 0 sum game, but they never mention poop as part of the equation. There seems to be an assumption that all food is absorbed at the same rate and across all people. Seems unlikely to me.

I wonder where/when this calories-in-calories-out trope ever made sense. Metabolism is so complex that the energy lost during reactions between and into metabolites cannot be measured - they happen inside cells mostly, at an insane rate. The mere presence of increased active thyroid hormone (T3) will elevate body temperature, leading to increased heat loss. Muscles become more efficient when used often. Muscles load glycogen after sports. Energy is conserved by warm clothing. Low room temperature leads to extra energy loss. Etc

How is one supposed to even approximate the energy balance without a fully body composition (dexa) scan every week?

> Metabolism is so complex

There's really not much variation in metabolism. Most peoples' metabolisms are within ~10% of the average. [0]

Of course, even a very small variation adds up when compounded over years. 100 extra calories a day is a 10 pound weight gain per year.

But the variation itself is actually small. No one can "eat twice as much and not gain weight."

[0] https://pubmed.ncbi.nlm.nih.gov/15534426

due to conservation of energy, energy lost during reactions between and into metabolites becomes body heat, which can be measured; also virtually all of it consumes inhaled oxygen, which can also be measured

Body heat can't be accurately measured. You can just measure heat loss via the surface. But there's variations on the cell level. Since heat can be stored inside the body for a longer period, measuring heat loss over a short period of time is not representative.

you are correct, but only for cold-blooded animals like reptiles

Why would that be? Eg Organs are warmer than hands etc - there certainly is a gradient. The heat from metabolic processes will not become obvious immediately because it’s redistributed before it’s lost to the environment.

in warmblooded animals core temperature is homeostatically regulated to high precision, preventing the kind of heat storage you're talking about

it sounds like you are unclear on the concept of energy

Is that an insult or? Your ten word comments are way too short to grasp the meaning you might be trying to convey.

I think we were referring to different sites of energy conversion.

no

think of it as a curriculum

I think calories in/out is just propaganda used to help the average person not overeat. Like most of the medical stuff were taught, it's a half truth because the systems are so complex that even the experts don't truly know.

Like sibling said, energy must be conserved. No matter how complicated the system is, calories in = calories out - the problem is that measuring (especially) the calories out part is tricky. What if you poop out your food mostly undigested? What if you spend your days half naked in a freezing cold unheated home? Etc

And because not even the experts know all the possible variables, from a practical perspective it's a half truth... so what there's conservation of energy, that doesn't give us any meaningful information to use for the application at hand.

There is if you expand eating less and moving more to being a surrogate endpoint instead of just being dials. If simply eating less causes a spontaneous reduction in activity that’s a signal. If changing what you eat lets you consume fewer (or desire more) calories for the same appetite/satiety that’s a signal. Paying attention to CICO is like having a gyroscope and accelerometer to help with navigation: leading indicators of where you’re heading until actual measurements (i.e. position/weight) confirm where you actually are. In fact it’s even better in this case because of how noisy weight is and needing multiple days (at least) to reliably judge the effect of an intervention.

For many people, those signals can be wrong and shouldn't be listened to.

There are too many aspects. Like gut flora and even enzymes present. Those could affect how and to what input is broken down. And then there are hormone responses and how body responses to those. In the end we are probably very far away of having complete understanding what is going on. And differences might be minute, but will add over years.

If your body temperature is too high you sweat to lower it. Thus you can have two people with the same body composition and yet different metabolism.

That seems possible -- it allows the rate of heat loss from the skin to be variable.

No it isn't the same for everyone. So what you do is: if you're gaining weight, eat less. If you're not, you're good.

Think that gets included in the calories out term.

It’s accounted for in the “calories in” component: the calories printed on the side of a package are the calories absorbed by an average body, not the total chemical potential energy of the food.

It doesn’t account for the thermocouple effect of food, otherwise protein would count for less than 4 kcal/g

That would require some sort of bioavailable calories metric that is specific to the person eating the food because I doubt people recalculate ther basic metabolic rate every single day.

At first I thought you were talking about the rats/mice/rabbits eating their own poop.

CICO is just a philosophy that says you can lose weight by measuring then reducing your caloric intake. It works vastly more often than not, so it's a useful trope. Just about everyone I've met who says it doesn't work refuses to measure their intake, and they just estimate that they must be eating less and not losing weight. Put what they eat on a food scale and voila! Turns out they overeat but don't recognize it.

Of course it works. Over eating causing fat gain has been known about for hundreds or thousands of years. The idea that it doesn't has always been an excuse and probably came from mischaracterizing science into psychological issues around obesity and food addiction.

What doesn't work very well is "curing" fat people by just telling them to eat less. Yes it would work if they could just eat less, but it does not address their actual problem which is the compulsion to over eat. Might as well try to cure alcoholics by telling them not to drink. So I understand why over eaters get upset about it, it's not like they don't know they eat too much and they don't want to be so fat. Though advancing the conspiracy theory that food intake has little to no bearing on weight is not a helpful response to that either.

The weight gains were 180 vs 280 grams.

While that is a significant difference, I still think calorie counting gives a useful estimate, since people eat many foods and the error reduces in aggregate, as some are overestimated and others are underestimated.

In addition, people are not rabbits and may have evolved digestive systems better adapted to reheated fats since the invention of cooking (evidence of campfires 1-2 My ago).

> So much for the reductionist and simplistic "calories in and out" trope brought up frequently on here.

That's how models work. They are simplified ideas to help people understand things. They're not intended to be an all encompassing theory of everything. Just like "supply and demand" works but breaks down in certain circumstances. In general "calories in, calories out" does work. The body may adapt, various foods affect you differently, but CICO is not a heretical idea.