> The fact that you think that there is a number like this shows you are using extremely old thinking about how even the CICO model works. There is no way to predict weight/gain loss amount based on calories across individuals.
But that's one of the few numbers you can predict with pretty good accuracy.
Figuring out diet, exercise, and BMR is the hard part. Expecting a pound of fat to go away per 3000 calories is the easy part.
> Figuring out diet, exercise, and BMR is the hard part. Expecting a pound of fat to go away per 3000 calories is the easy part.
Well, here you've moved from "estimated deficit per day" to "exact total deficit". Sure, thermodynamics tells you with absolute certainty that if you've lost 1 pound of fat in 1 week, you've overall had 3000 Cal deficit in that month.
But that doesn't mean you can say "if you know your BMR at time t, eat exactly this much and exercise exactly this much, you will definitely have a 3000 Cal deficit over 1 week". This would assume already that BMR doesn't vary with exercise and diet. It also assumes that food digestion doesn't vary with exercise and diet. Both of these are assumptions that we don't really know. And even if they are true for 1 week, they are almost certainly not true for 1 year.
But that's one of the few numbers you can predict with pretty good accuracy.
Figuring out diet, exercise, and BMR is the hard part. Expecting a pound of fat to go away per 3000 calories is the easy part.