I'm not sure how I could have made that any clearer. I included (show correlation) specifically for that very reason.

But not causation and still didn’t explain whether that could be explained by the standard CICO equation.

CICO is a copout. Calories in is relatively simple. Calories out is hideously complex. When people describe weird things that metabolism does, real or fake, they're things that shift the Calories Out numbers way beyond the simple results you get from body composition and exercise level.

There are so many separate ways for calories to go "out", too.

So it gets used in this unfair double-standard way, where managing weight is "just CICO", as if it's a handful of inputs into a one-line equation, but if someone argues against that, saying it's more complex, then the natural response is "well actually CICO includes every single complication you've mentioned, so you're wrong to object".

It is just CICO, whether you won the genetic lottery that makes the calculation simpler or not doesn't mean it's any less of a cop out than saying that it would be simpler for me to be a great basketball player if I were 6 foot 8 instead of 5 foot 5.

Something can be both true and used in a misleading manner.

To use your same metaphor, there are people going around speaking as if height and total hours of training are the only things that matter for basketball skill.

Understand that there are necessary and sufficient conditions. A sufficient condition for obesity is too high chronic caloric intake. A necessary condition is retention of this surplus. Some people will feel correctly full when they overeat high calorie foods, others only if volume is too big, yet others have the distended stomach where even that does not work. Some have hormonal deficit that makes them retain more (e.g. hypothyroidism) or counters satiety signaling. Others have very wasteful metabolism or digestion where less is retained. Some really do highly strenuous activities that just demand more energy.

Ultimately you set a caloric target with a carefully constructed diet and watch the long term weight slope over months. That's the science of it. Even high fat ad lib diets ultimately resulted in caloric input restriction, stronger than other diets they tried. (see Cambridge study)

> Ultimately you set a caloric target with a carefully constructed diet and watch the long term weight slope over months. That's the science of it. Even high fat ad lib diets ultimately resulted in caloric input restriction, stronger than other diets they tried. (see Cambridge study)

Agreed, but I'd characterize all that as focusing on the "Calories In" part. That's complicated enough itself, and avoids implying that the entire situation is some trivial function.

> Calories in is relatively simple.

There are at least two categories of issues that make calories in not so simple: eating disorders and malabsorption disorders.

You might try clicking the link I provided. The Wikipedia page details the virus and provides links to other sources one of which was conducted on chickens where they measure input/output and still saw positive weight gain.

So exactly how do you explain mass just coming out of nowhere?

I think all berdon is trying to say by "not simple physics" is that even though CICO is true, it's not helpful to people trying to lose weight because there are many other conditions (e.g. a virus) that can affect the body's metabolism - to a limited extent. This particular virus seems to make you fatter even on a precise calorie controlled diet, which implies it must reduce your metabolism.

For the record I disagree with this - I think CICO is a helpful way to think about weight loss, because it implies that if you aren't losing weight on a calorie controlled diet, you simply haven't cut enough. (Though serious problems might be indicative of some medical condition, in which case you should consult a doctor to see if it can be alleviated to make CICO easier.)

CO may be difficult for a person to manipulate, and raising CI to put on weight may be physically difficult, expensive, or ineffective. However, reducing CI takes willpower but will make you lose weight. If you reduce it enough. Somebody may have a CO so low that the reduction in CI required to lose weight might require medical supervision (e.g. to prevent malnutrition.) That's probably not the case for most people though; certainly not people like myself. If I mustered the willpower to eat less, I would doubtlessly lose weight.

If I were to fall for some of the new-age mumble jumble about weight being some innate genetic trait like iris color, I'd think myself helpless. If I were such a person, being informed of CICO would doubtlessly improve my life.

> However, reducing CI takes willpower but will make you lose weight. If you reduce it enough. Somebody may have a CO so low that the reduction in CI required to lose weight might require medical supervision (e.g. to prevent malnutrition.) That's probably not the case for most people though; certainly not people like myself.

Yes, this is exactly my point. I'm simply giving a measured defense of what berdon has been saying further up this thread: CO is not a known constant and may vary based on certain medical conditions. Because of this, CICO can sometimes (I think berdon would say frequently) be unhelpful advice to someone trying to lose weight, because they struggle with cutting CI far enough to lose weight, which may be due to a person's health and biological makeup.

Then I think berdon's concerns are misprioritized. It's very rare for the necessary reduction in CI to require medical supervision. The overwhelming majority of obese people in America are eating more than is reasonable to eat, and a reduction in consumption would improve their lives considerably with no real risk of malnutrition occurring.

By focusing on obscure edge-cases, all we're really doing is to make it easier for people in the common case to rationalize away their situation. That's very common. There are more voluntary overeaters who claim they have an involuntary obesity-inducing disorder than there are people who actually have such disorders. I've got a whole family full of them. A big bowl of ice cream after every meal is a choice, not a genetic condition.

Partialrecall - my concerns are my own but the point I was attempting to make has nothing to do with what you're talking about. All of which I agree.

My point is the body is very complex and any attempt to simplify it is doing a disservice to anyone listening to you.

I was overweight for 20 years and lost the weight by calorie reduction. It works - clearly. But in a forum reserved for educational discussion I'm not OK glossing over the complexity of the body because it's true in the general case. That'd be as sinful as saying quantum physics is wrong because newtonian is generally the deciding set of rules.

Nobody is glossing over it, it is subject of active research. Until that research produces any generally useful results (drugs, tests, treatments), the advice stays the same.

We know exactly one applicable test: thyroid hormone levels. This one is worth checking.

Eat less everything but more fresh vegetables, especially greens, exercise more. How much depends on how fat you are - not necessarily just overweight, body composition and fat percentage is more important and still reliably measurable.

"Toffee" kind of fat is a thing, where a thin looking and not very heavy person is actually fat inside, just lost muscle so weight stayed similar.

On the other hand, nobody wants people with big muscle mass to always cut diet to levels expected of show body builders.