Recomposition is the case people expect to break an algorithm built on bodyweight: you are changing substantially, and the scale reports nothing. It turns out the estimate does not need to see it.
Why the estimate stays right
Your expenditure is measured from what you ate and where your energy stores went. If your trend weight is flat and your logging is honest, your stores are roughly level, and the arithmetic says your expenditure equals your intake. That is true whether the kilo you are holding is the same kilo as last month or a rebuilt one.
Composition only enters the calculation when weight is actually moving, because that is when the app has to price the change. A kilogram of fat carries about 9,400 kcal; a kilogram of lean tissue about 1,800. The app blends the two using your body fat percentage and your bodyweight — a heavier body at the same percentage carries more fat mass, and mobilises proportionally more fat per kilo lost. That blend is why keeping your body fat percentage current matters: it is the input that decides what a moving scale is worth.
What to watch instead
The scale is simply the wrong instrument for this. Two better ones are already in the app:
- Body measurements. Ten circumferences plus body fat. A waist that shrinks while shoulders hold is recomposition in numbers, and the scale will never show it to you.
- Progress photos. Same pose, same light, weeks apart. This is the change photos are best at.
What to expect from your targets
A flat trend at a deficit target will eventually pull your calorie target down at check-in: the app is reading maintenance and doing the arithmetic. If you are deliberately recomping, that is the moment to use keep rather than apply and hold your intake where it is — apply or keep your targets explains the choice.
Two honest caveats. Recomposition is slowest in trained lifters and fastest in people returning after a break or starting out, so a flat scale is not by itself evidence that it is happening. And a flat trend with unlogged food is indistinguishable from recomposition at the level of the estimate — the difference is in the diary, not in the number.