Seems like this is what your asking Do calories matter? « The Eating Academy | Peter Attia, M.D.
I have just one question, but I will ask it in a few different ways so you can see exactly what I'm looking for and you can take your pick at which one(s) best get(s) at the heart of the issue.
The "context of calories" discussion is helpful in showing that body composition is not simply a matter of "calories-in/calories-out," and that hormones (esp. insulin) are one factor that is substantially related to regulation of adipose tissue, but what do you make of the oft-touted 2nd law of thermodynamics as it relates to human metabolism? I.e. the proposition/assumption that your body must do something with each and every calorie that you consume?
So if fat accumulation is influenced substantially by insulin, what happens to the extra calories when there is a positive energy balance sourced from a low carb, high fat diet? Why can some people eat excess calories sourced from fat/protein and not gain weight, but as soon as they start eating carbs they pack on pounds? Where are those calories going?
One more to illustrate - if person A is gaining their daily caloric intake from 50% carbs and ends up accumulating excess fat, and that person's twin (B) eats the same amount of calories, but sourced primarily from fat and protein without fat gain, what is happening to those calories which in Diet #1 are being stored as fat?
The laws apply to isolated systems only which we are not...
and no system can be 100% efficient in using all the energy you give it (some energy wasted as heat or in some other process)
if you overeat you will gain weight
“There is immeasurably more left inside than what comes out in words…”
— Fyodor Dostoevsky
Think of the human body like a car~ some get 30 MPG and go 60 MPH, others go the same speed but 'spend' 20MPG. Everyone is unique, even twins.