But the calories out side varies among individuals. Bodies aren't 100% efficient at extracting compounds between eating and excreting. Two people can eat the same exact foods, do the exact same exercises, and gain or lose different amounts of weight.

I don't think anyone's seriously claiming that everyone will react the same to diet and exercise, or that "calories in - calories out = weight lost" is the only word on weight loss.

It is, however, the final word.

So, you've made - repeatedly - the completely obvious point that, if you can account for every term in the equation, calories in - calories out = change in weight.

Thank you for that. Now if you'd like to adopt the assumption that your audience isn't brainless, let's talk about the interesting point that everyone wants to be talking about: that the 'calories out' number varies for the same 'calories in' number across people, diets, and behaviors.

And the stored calories, like body fat and glycogen? What side of the equation are those on? And the energy needed to convert complex carbs and protein into glycogen? The energy used converting glycogen to ATP?

If you can demonstrate everywhere the energy comes from and everywhere it goes and where and how it's used in the body, I imagine there's a nobel prize in it for you. There's still a lot we don't know about where all that energy comes from and goes.

>And the stored calories, like body fat and glycogen? What side of the equation are those on?

Weight loss...

>And the energy needed to convert complex carbs and protein into glycogen?

Energy out...

>The energy used converting glycogen to ATP?

Energy out...

The body is complex. Energy in - energy out = weight lost its not.