Two steps: a resting burn, then an activity multiplier
BMR is what you'd burn lying in bed all day, from the Mifflin-St Jeor equation: 10×weight(kg) + 6.25×height(cm) − 5×age, then +5 for men or −161 for women. Multiply that by an activity factor and you have your maintenance calories. The factor does the heavy lifting, so getting it right matters more than the BMR digits.
Activity factors
| Level | Factor | What it means |
|---|---|---|
| Sedentary | 1.2 | Desk job, little or no exercise |
| Lightly active | 1.375 | Light exercise 1–3 days a week |
| Moderately active | 1.55 | Exercise 3–5 days a week |
| Active | 1.725 | Hard exercise 6–7 days a week |
| Very active | 1.9 | Physical job or twice-daily training |
The gap between sedentary and very active is over 50%. For a BMR of 1,700, that is 2,040 vs 3,230 calories a day, so honest self-assessment here changes the answer more than anything else.
Maintenance, deficit and surplus
- Maintenance — eat your TDEE and weight stays flat. This is your baseline, not a goal in itself.
- Deficit — 250 to 500 below maintenance loses roughly half a pound to a pound a week. Deeper cuts stall as your body adapts.
- It moves. Maintenance drops as you lose weight and falls about 2% per decade after 30, so a number from a year ago may already be too high.
Common questions
What are maintenance calories?
The number of calories that keeps your weight steady. Eat that amount and the scale holds; eat below it and you lose, above it and you gain. It is the same figure as your TDEE, or total daily energy expenditure.
How is TDEE calculated?
Your body works out a resting burn (BMR) from weight, height, age and sex using the Mifflin-St Jeor equation, then multiplies it by an activity factor from 1.2 for a desk job up to 1.9 for hard daily training.
Which activity level should I pick?
Most people overestimate. A desk job with occasional walks is sedentary (1.2). Training three to five days a week is moderately active (1.55). Pick the lower level and adjust after two weeks of tracking your actual weight.
How many calories below maintenance to lose weight?
About 500 below gives roughly 1 pound (0.45 kg) of loss per week; 250 below gives about half that and is easier to sustain. Recalculate every 5 to 10 kg lost, since a lighter body needs fewer calories.
