It doesn't though, at the end of the day there's an objective amount of CI and an objective amount of CO. Further, CO isn't just "activities", for instance you burn calories merely by existing. Things you're describing will impact CI and CO, but at the end of the day if one had the ability to fully and 100% accurately measure CI & CO it'd be apparent that the math works.
But this is why "it's just CICO" is at best a tricky phrase. Because the hard part is in the nuance you describe.
I get this over and over on every issue where "math" becomes "guidance". Let me try to bridge by restating:
Math truth is not always good policy guidance.
It is true that CI==CO. It must.
It is not true that telling someone that CI==CO is a good way to get them to manage their weight, because (as mentioned) it's hard to measure and (as I added) even if you measure correctly, you _reduce likelihood of compliance_ by ignoring appetite effects when you call all calories equal.
I think we agree, just trying to find the right words anyway.
It doesn't though, at the end of the day there's an objective amount of CI and an objective amount of CO. Further, CO isn't just "activities", for instance you burn calories merely by existing. Things you're describing will impact CI and CO, but at the end of the day if one had the ability to fully and 100% accurately measure CI & CO it'd be apparent that the math works.
But this is why "it's just CICO" is at best a tricky phrase. Because the hard part is in the nuance you describe.