> What does base metabolic variability have to do with using CICO to modify your weight?

Metabolic syndrom is characterised by the basal metabolic rate reducing in response to reduced calorie intake or increased caloric expenditure. In most of us this is good. It gets the immune system to quit mucking around, for instance. In the obese, however, it can sometimes mean their bodies will literally stop doing essential shit before it will concede and begin burning fat. It will then do everything it can to refill those fat cells.

You can model a human thermodynamically. But to my knowledge, this isn't used in medicine because it isn't practical. (I'm saying this, by the way, as someone who can eat anything and laze around and not gain weight because my metabolism is tuned the other way.)

CICO reminds me of something we do in finance: burying the complexity in a magic variable. For CICO, it's the CO. Because if you decompose it into its active and inactive components. Exercise is the former. But the latter absolutely dominates that term.