Bodies are complex. Less in More Out is only true and a matter of physics if our bodies can never refuse to absorb a calorie, or ever change gears to add tasks

Bodies are complex. Less in More Out is only true and a matter of physics if our bodies can never refuse to absorb a calorie, or ever change gears to add tasks (such as extra DNA-repair) in times of surplus rather than always resort to mere storage. It's very unlikely that that's true. Merely altering the speed of motility through the GI tract (degree of peristalsis) alters the action of our biota and substantially changes how many calories and nutrients are available to be absorbed, as one small example.