If it’s not a big difference, how does it lead to such divergent results? I’d suggest that a 4% difference is in fact pretty big, as that’s the equivalent of over 500 calories a week.

Do you have a link for the evidence? I’d be interested to see what it says about calorie absorption, as I suspect that has an even greater effect. Unfortunately, everyone just seems to repeat CICO as though it’s easy or simple to measure either of those inputs with accuracy. People just hope they’re average and that it will work normally for them. Most people are average, so that works for a lot of people, but not everyone.

I personally don’t digest animal fat well, so anything other than white meat chicken will give me the shits. I don’t eat animal products anymore, but when I did, I obviously wasn’t receiving 200 calories from 200 calories worth of beef. My sister has celiac’s, and when she realized it and stopped eating gluten, she gained a bunch of weight, because she was finally absorbing calories from her diet.