Maintenance calories

Maintenance calories are the intake that matches total daily energy expenditure, so body mass holds steady. It is the reference point every deficit or surplus is measured from.

It matters because a calculator's estimate is only ever a starting guess. The reliable way to find your real maintenance is to eat a consistent amount for two to three weeks and watch the trend of your weight, using a weekly average to see past day-to-day fluid swings.

In practice it is not a fixed number. It moves with body mass, with activity, with NEAT — which quietly falls when you diet — and with the metabolic adaptation that accompanies sustained energy restriction. Re-checking it periodically matters more than getting the first estimate right.