[Black Agnes]

Isocaloric != isometabolic. Your metabolism != laboratory calorimeter.

Technically, laboratory calorimeters can determine the caloric content of wood fiber. In your body that’s pretty close to zero. Unless you’re a flagellate in the intestine of a termite. Not so in a lab experiment, by the strict definition calorie.

[Mase]

It's unfortunate you never learned how a calorie is defined. It also appears you didn't learn that metabolizing fat, carbs and amino acids require different pathways, and that the efficiencies will not be the same for all of the processes. You, like so many others, are confused about calories and efficiency. Why am I not surprised?