Or higher basal metabolism and higher activity levels ... Both of which would increase CO...

But we're getting out track , my point is simply that CICO expresses a relationship between calorie in , calorie out and the variation in people weigth . It's doesn't say that one can control people weigth using CI. The analogy that Judea pearl uses is that there is a relationship between the number displayed on a thermostat and the temperature outside , but that does not imply that one can control the temperature outside by changing the number displayed on the thermostat