What is TDEE? Total daily energy expenditure
TDEE is the energy you burn in a day: BMR, digestion, exercise and everyday movement. What each part adds up to, and why any number is an estimate.
What is TDEE?
TDEE, or total daily energy expenditure, is the number of calories your body burns in 24 hours. It is the sum of four parts: basal metabolic rate (the energy to stay alive at rest), the thermic effect of food (digestion), exercise, and non-exercise movement such as walking and standing. Eat at your TDEE and your weight holds roughly steady.
How to estimate your TDEE
- Estimate your BMRUse an equation such as Mifflin-St Jeor with your weight, height, age and sex. This is the energy you burn at complete rest.
- Multiply by an activity factorFactors run from 1.2 for a desk job with no exercise to about 1.9 for a physical job plus daily training. Pick the lower one if you are unsure.
- Log intake and weight for two to three weeksEat as you normally do, log what you eat, and weigh yourself several mornings a week. Compare weekly averages, not single days.
- Correct the estimate with your dataIf your weight held steady, your average intake is close to your TDEE. If it moved, adjust by about 7,700 kcal per kilogram of change, spread across the days.
TDEE is the number behind every calorie target. A deficit, a surplus and “maintenance” are all measured against it. It is also the number most people get wrong, because it is not a fixed trait. It moves with your size, your job, your training and how much you fidget.
The four parts of TDEE
| Component | What it is | Typical share of TDEE |
|---|---|---|
| Basal metabolic rate (BMR) | Energy to keep organs working at complete rest | About 60–70% for a lightly active adult; less with a physical job |
| Thermic effect of food (TEF) | Energy spent digesting, absorbing and storing food | About 10% |
| Exercise | Planned training: lifting, running, classes, sport | Often 5–10%; close to zero if you don’t train, more for endurance athletes |
| NEAT | All other movement: walking, standing, chores, fidgeting | The most variable: a small slice for desk-bound people, half or more for very active ones |
BMR is the largest part for almost everyone. It is driven mostly by lean mass: organs and muscle use energy even when you lie still. What BMR is and what moves it covers it in detail.
TEF is the cost of processing food. Protein costs the most, roughly 20–30% of its own calories, compared with about 5–10% for carbohydrate and 0–3% for fat. On a mixed diet it comes to about a tenth of what you eat.
Exercise and NEAT together make up activity. Planned exercise is smaller than most people think: a typical hour of lifting burns a few hundred calories, not a thousand. NEAT is the walk to the station, the hours standing at a counter, the laundry. It is where most of the difference between people lives, and NEAT has its own page.
A worked example
Take a 35-year-old man who weighs 80 kg, stands 180 cm tall and trains three to five days a week. The Mifflin-St Jeor equation (1990) puts his BMR at 1,755 kcal: (10 × 80) + (6.25 × 180) − (5 × 35) + 5. Multiply by the moderate activity factor of 1.55 and his estimated TDEE is about 2,720 kcal.
Split that number back into its parts. BMR is 1,755 kcal, about 65%. TEF, at roughly 10% of what he eats at maintenance, is about 270 kcal. That leaves about 690 kcal, or 25%, for exercise and NEAT combined.
The activity factor is the weak link. The same man at 1.2 (sedentary) comes out at 2,106 kcal. At 1.725 (very active) he is at about 3,027. That is a gap of more than 900 kcal from one choice on a dropdown, far bigger than the difference between equations. To run your own numbers, use the TDEE calculator.
Why two people of the same size burn different amounts
Two people can share a weight, height and age and still have TDEEs hundreds of calories apart.
- Body composition: More lean mass means a higher BMR. The Katch-McArdle equation, which works from lean mass, gives an 80 kg person at 15% body fat about 1,839 kcal and the same weight at 30% body fat about 1,580. That is a 259 kcal gap before anyone moves.
- Daily movement: According to the research of James Levine at the Mayo Clinic, NEAT can differ by up to about 2,000 kcal a day between people of similar size. A nurse on a ward and a programmer at a desk live in different energy worlds.
- Training: Type, volume and intensity all matter. An hour of steady cycling costs more than an hour of heavy triples with long rests.
- Biology: Thyroid hormones, genetics and other factors nudge BMR up or down, and part of the difference between people has no clean explanation.
Why TDEE is always an estimate
The reference method for measuring TDEE in daily life is doubly labeled water, an expensive lab test that tracks harmless isotopes leaving your body over one to two weeks. Everything else is a prediction. BMR equations are built from group averages, and even the best of them can be off by 10% or more for one person. Activity factors are rougher still.
TDEE also moves. Lose weight and there is less of you to fuel and carry, so it falls. Diet hard and you may move less without noticing. Start a physical job, add a daily walk, or spend a week ill in bed, and it shifts again. Treat any number as a starting point you will correct.
The correction is simple arithmetic. Say you averaged 2,400 kcal a day for three weeks and your weekly average weight fell by 0.3 kg a week. That loss implies a daily shortfall of about 330 kcal (0.3 × 7,700 ÷ 7), so your real TDEE is closer to 2,730. If your weight held steady, your TDEE is close to 2,400. The result is only as good as your logging, so log the oil and the drinks too.
Common mistakes
- Counting exercise twice: Activity factors already include your training. Adding a watch’s workout calories on top inflates the estimate.
- Overrating activity: Three gym sessions a week with a desk job is light to moderate, not very active.
- Trusting one week of data: Water, salt and carbohydrate can swing the scale by a kilogram or more from day to day. Judge trends over two to three weeks.
How FORM uses it
FORM sets your starting calorie target with Mifflin-St Jeor multiplied by an activity factor, then adjusts it for your goal, with the weekly pace capped relative to body weight. Every target is editable. FORM also reads steps and active calories from Apple Health or Health Connect, and the weight tracker charts the trend you need to check whether the estimate is right.
FAQ
Is TDEE the same as maintenance calories?
In practice, yes. Maintenance calories are the intake that keeps your weight steady over time, which is your TDEE averaged across normal days.
What is the difference between TDEE and BMR?
BMR is only the energy you burn at complete rest. TDEE adds digestion, exercise and all other movement on top, so it is always higher.
Should I eat back the calories my watch says I burned?
Not if your target already uses an activity factor that includes training. Wrist-based calorie estimates can also be well off, so treat them as rough.
Does TDEE go down as you lose weight?
Yes. A smaller body costs less to run and to move, and many people move a little less while dieting. That is why progress slows at the same intake.
How often should I recalculate my TDEE?
After every few kilograms of weight change, or when your job or training changes a lot. In between, let your weight trend tell you whether the estimate holds.