The plain-English definition
Your maintenance calories are what your body spends in a typical day — heartbeat, brain, digestion, fidgeting, walking to the kettle, and any workouts. Nutrition people call it TDEE (total daily energy expenditure). Eat exactly this number and your weight stays put. Eat under it and you lose; over it and you gain. Every diet ever invented is a strategy for staying under this one number.
What's inside the number
- BMR (60–70%): what you'd burn in a coma — driven by your size, age and sex. This is the big, boring, non-negotiable slice.
- Daily movement / NEAT (15–30%): steps, chores, fidgeting, standing. The most variable slice — and the reason two same-sized people can differ by 400 kcal a day.
- Digestion / TEF (~10%): processing food costs calories. Protein costs the most, which is one of its quiet advantages.
- Exercise (0–15% for most people): smaller than the gym mirror suggests. A hard 45-minute session is ~300–450 kcal — real, but not license for a large pizza.
How to calculate yours
Formulas like Mifflin-St Jeor estimate BMR from your sex, age, height and weight; multiply by an activity factor (1.2 sedentary → 1.7 very active) and you have a TDEE estimate. Two honest warnings: people overrate their activity level (a desk job plus three gym visits is "lightly active," not "very active"), and any formula is a population average with a ±10% error bar for individuals. Treat the output as a starting guess, then let 3–4 weeks of scale trend correct it.
The measured method beats the formula: track intake honestly for two weeks alongside daily weigh-ins. Flat trend = you found maintenance. Falling ~0.5 kg/week = you're ~500 under. Your body just told you its number.
The part everyone misses: the number moves
Maintenance isn't a constant — it follows your body size down. Lose 6 kg and your TDEE drops by roughly 120–150 kcal/day. Diets "stop working" on schedule because the target that was a 500-kcal deficit in January is a 300-kcal deficit by April. Nothing broke; the anchor moved. Recalculate every few kilos, or use a target that recalculates itself.
Maintenance calories in Calfit
Calfit runs the estimate during onboarding — age, height, weight, activity, goal — and sets your daily target from it. Then it does the thing formulas can't: it watches your weigh-in trend and quietly re-anchors the target as your real-world numbers come in. Your maintenance stays current without you ever re-opening a calculator, and Pip never once says "TDEE."