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Violations of Calories in, calories out

Simple violations

• Have your hand chopped off. Total calorie value of your body does NOT match your ingestion.
• Eat a laxative or something to make you vomit right after eating.
• Eat a food which actively destroys digestive enzymes.
• Eat a nanite which literally destroys glucose in your blood.
• Eat a nanite which literally destroys fat cells and causes them to be emitted from your body.
• Eat a hard small nut with super high density sugar inside, which doesn't get digested - i.e. birds eating seeds which they can't digest. In your calculations of calories consumed by birds, have you evaluated their digestive efficiency?

Okay you may say these are all cheats because it's "really" about "fully digesting" the food. But yes, that's the whole claim in the first place. Defenders of the claim retreat to "calories actually absorbed" when challenged, but normally present it as "Calories going in your mouth". But even absorption is not really clear since you can still lose calories this way too.

The missing calculation is "Calories out" also includes nutrition not absorbed. But the conventional way to figure out calories of a food assumes 100% conversion, right? So this is clearly a hole. If you use "calories in" derived this way, and only consider exercise as a way to generate calories out, it's no wonder that your predictions don't come true.

Another scenario

• Give someone 2k calories, once a day
• Give someone 4k calories, every 2 days
• Give someone 40k calories, every 20 days

Do you really claim that their weight would be identical in these cases? Even assuming identical exercise and heart rate profiles.

Okay, how about "Give someone 100k calories, every 50 days". Why does your model fail here?

Are you so sure you want to use weight?

• Feed someone 2 pounds of water => I have changed their weight with no calorie change. So what even is the original claim? It's actually about distribution of non-water mass.
• When someone breathes in the air has weight - and yet it has no calories.

So the claim is unclear.

Even more example

• 2k calories in twinkies vs 2k calories in lysine (pure lysine)

Why in the world would you think the results after a month of this would be the same?

So around the naive claim is a million unstated assumptions - which are actually being violated in reality all the time. What's probably really happening is that the response curves for absorption and retention for different types of ingredients are not the same; you have differing scopes to "gain weight/muscle/fat" based on the dynamic situation.

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