This is something I've said repeatedly in other places and this is a certain segment of people who can't understand it.

CICO is, especially at the population level, terrible dieting advice. We have decades of experience and oodles of research showing that, as advice it does not work.

However, it is, as you point out, basically tautologically true/correct. For CICO to _not_ be correct would essentially be breaking physics and generating mass/energy from nothing.

Yes, your body can change it's energy expenditure in response to dieting, but this is accounted for in the CO part of CICO. If you consume fewer calories than your body expends (in all the myriad of ways that your body can/does expend calories), then you _must_ lose weight.

The fact that CICO is true does not make it good advice but the fact that it's bad advice doesn't make it false.