The Difference in One Sentence
Basal metabolic rate is the energy your body burns at complete rest, keeping your organs, breathing and body temperature running. Total daily energy expenditure is that figure plus everything else you do: digesting food, walking around, and any deliberate exercise. BMR is an input to the calculation; TDEE is the number you set calorie targets against.
The Difference in One Table
| BMR | TDEE | |
|---|---|---|
| Stands for | Basal metabolic rate | Total daily energy expenditure |
| Measures | Energy at complete rest | Energy across a whole normal day |
| Includes | Organ function, breathing, circulation, temperature | BMR plus digestion, movement and exercise |
| Typical adult | ~1,300–1,800 kcal | ~1,800–2,700 kcal |
| Use it for | An input to the calculation | Setting your actual calorie target |
The mistake to avoid: eating at your BMR. It is not a target. It is what your body would burn if you spent the entire day unconscious, and eating at that level while living a normal life creates a far larger deficit than intended.
What Makes Up Your TDEE
- BMR, roughly 60–70%. The largest share by a wide margin, and mostly outside your control.
- Thermic effect of food, roughly 10%. The energy used digesting and absorbing what you eat. Protein costs noticeably more to process than fat or carbohydrate.
- Non-exercise activity, roughly 15–30%. Walking, fidgeting, standing, housework. Enormously variable between people, and it tends to fall quietly during a diet.
- Deliberate exercise, roughly 5–15%. Usually the smallest component, which surprises people.
That last pair is worth sitting with. For most people, daily incidental movement moves the needle more than gym sessions do, which is why step count is such a useful thing to watch.
Calculating Yours
Start with the Mifflin-St Jeor equation, the current standard for estimating BMR:
Women: BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161
Then multiply by your activity factor: 1.2 sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 very active, 1.9 extremely active.
Worked example. A 40-year-old man, 180 cm, 85 kg, moderately active: BMR = 850 + 1,125 − 200 + 5 = 1,780. TDEE = 1,780 × 1.55 = 2,759 calories.
Pick Your Activity Factor Honestly
This is where most estimates go wrong. People choose the factor describing the life they intend to live rather than the one they actually live. Three gym sessions a week alongside a desk job and a car commute is "lightly active", not "very active".
When unsure, choose the lower band. If the resulting trend shows you losing faster than intended, you can raise it.
Why Your TDEE Falls as You Lose
A smaller body costs less to run. Less tissue to maintain, less mass to move. On top of that, non-exercise movement often declines during a diet without any conscious decision.
The practical consequence is that a calorie target set at the start of a diet becomes progressively less of a deficit as you succeed. This is a large part of what people experience as a plateau. Recalculating every 4 to 6 kg keeps the target honest.
The Equation Is a Starting Point
Mifflin-St Jeor was derived from population data, so individuals scatter around it. Body composition matters too, since muscle is more metabolically active than fat, and equations based on total body weight cannot see that.
The reliable approach is empirical. Eat at your calculated target for two to three weeks, track intake consistently, watch the weight trend, and adjust. Your own data beats any equation.
Skip the Arithmetic
SlimPanda calculates a starting calorie and burn target from your age, height, weight and goal during a short setup.