What TDEE means
Total daily energy expenditure is every calorie your body spends in 24 hours: staying alive, digesting, walking to the kitchen, and any deliberate exercise. Eat that number and your weight holds. Eat below it and you lose. This is your maintenance level, and it is the reference point every calorie target hangs from.
It is not the same as BMR. Basal metabolic rate is only the resting portion — the calories you would burn lying still all day. For most people BMR accounts for roughly 60–70% of the total, so setting a target from BMR alone puts you a long way below where you meant to be. If you want the resting number on its own, use the BMR calculator.
The four things you burn calories on
| Component | Share of TDEE | What it is |
|---|---|---|
| BMR | 60–70% | Organs, breathing, circulation, cell maintenance |
| Thermic effect of food | ~10% | Digesting and absorbing what you eat |
| Non-exercise activity | 15–30% | Walking, fidgeting, standing, chores |
| Exercise | 0–15% | Deliberate training |
The surprise for most people is the third row. Incidental movement varies enormously between individuals — a job on your feet versus a desk can be several hundred calories a day, which is more than most gym sessions. Deliberate exercise is usually the smallest slice, not the largest.
How the calculation works
Step one: BMR. The Mifflin-St Jeor equation is the current standard:
- Men: (10 × kg) + (6.25 × cm) − (5 × age) + 5
- Women: (10 × kg) + (6.25 × cm) − (5 × age) − 161
Step two: multiply by your activity factor.
| Activity level | Multiplier | Roughly |
|---|---|---|
| Sedentary | 1.2 | Desk job, little movement |
| Lightly active | 1.375 | Light exercise 1–3 days a week |
| Moderately active | 1.55 | Moderate exercise 3–5 days |
| Very active | 1.725 | Hard exercise 6–7 days |
| Extra active | 1.9 | Physical job plus training |
Worked example. A 32-year-old woman, 165 cm, 68 kg, moderately active: BMR = (10 × 68) + (6.25 × 165) − (5 × 32) − 161 = 680 + 1,031 − 160 − 161 = 1,390 kcal. TDEE = 1,390 × 1.55 = about 2,150 kcal.
Note the gap. Her BMR is 1,390 and her maintenance is over 2,150 — a difference of more than 750 calories a day.
Why generic numbers like 1,200 miss
Put that example next to the most-repeated number in dieting. For this woman, 1,200 calories is not a moderate deficit — it is roughly 950 below maintenance and below her resting requirement. That is the territory where energy, sleep, training quality and nutritional adequacy all start to suffer, and where the plan usually ends. We wrote about that pattern in the truth about 1,200-calorie diets.
The problem with 1,200 is not that it is low. It is that it is arbitrary. It was not calculated from anyone in particular, so for one person it is punishing and for another it is barely a deficit at all. A number that ignores your height, weight, age and daily movement cannot be right except by accident.
Turning TDEE into a daily target
Once you have the figure, the rest is subtraction:
- Maintain: eat at TDEE
- Lose about 0.5 lb a week: TDEE − 250
- Lose about 1 lb a week: TDEE − 500
- Gain slowly: TDEE + 250 to 300
Three practical notes. Treat the result as a starting hypothesis and adjust after two or three weeks of real data — the equations are population averages and yours may sit 10% either side. Recalculate after every 10–15 pounds of change, because a lighter body has a lower TDEE. And avoid setting a target below your BMR; if the arithmetic demands it, the timeline is too aggressive rather than the number being wrong.
For the goal-range view alongside protein and water targets, the maintenance calorie calculator runs the same equations and lays out loss and gain bands together.