I have banged on why calories doesn't explain the full picture probably a dozen times on this site, and I'm not sure I want to go into that any more.

Yes, "thermodynamics". But we are not a simple furnace (which is by the way the very thing used to calculate the calories in food. A furnace). We are a complex machine with thousands of chemical pathways, feedback loops, some more efficient than others. You do not eat pure energy, you eat organic matter that is chemically turned into multiple forms of energy.

Nothing has been a better ally to the obesity epidemic than CICO (calories in, calories out)

> Nothing has been a better ally to the obesity epidemic than CICO (calories in, calories out)

I doubt that's true. The availability of Mars Bars and magic food diets (Fat is bad! No, now carbs are bad!) are more likely culprits. People don't fail to lose weight if they count calories. People fail to stick to their diets if they count calories, because it's a joyless activity; biology divorced from psychology.

The Mars Bar is available and says "can be part of a healthy diet" BECAUSE of the calorie bullshit. People see "it's only 250 calories" and "it's less fat than cheese" and happily chomp on them, while demonising red meat or saturated fat.

I genuinely don't see a logic chain of reasoning from you. 250 calories is massive. If someone were worried about calories they wouldn't be eating something that's over 10% of their daily allowance.

The "it's less fat than cheese" isn't a calorie thing. You seem to be mixing things up.

I used to think it was as simple as calories in/out, until I learned that certain fibers (and their calories) and totally non absorbable by the body, so their calorie content doesn't matter...among other things that don't follow the in/out rule.

The often forgotten assumption of the "calories out minus calories in is all we need to look at" is that the metabolic rate is independant of the kind of food we ingest.

There is also food => inflammation change => body water gain/loss.