What TDEE actually is
TDEE is your basal metabolic rate — the energy your body burns just staying alive — multiplied up to account for how much you move. It is the number that matters for weight change: eat consistently under it and you lose weight, over it and you gain, near it and you stay put. Everything else in nutrition is detail on top of this.
Which formula to pick
- Mifflin-St Jeor — the default. Most accurate for most people in validation studies, and what dietitians use.
- Harris-Benedict — the 1919 classic, revised 1984. Runs a little higher; useful for comparison.
- Katch-McArdle — computes from lean mass, so it needs your body fat percentage. The best choice if you are unusually muscular or lean, because the others assume an average build.
Whichever you pick, treat the result as a starting estimate. Track your weight for two or three weeks and adjust by 100–200 kcal if it moves the wrong way — your real TDEE is the number where your weight holds steady.
Honest expectations about activity level
The multiplier is where most people overshoot: desk workers who train three times a week usually belong in lightly active, not moderately active. If you are unsure, pick the lower level — it is easier to add calories later than to explain a stalled diet.
Frequently asked questions
TDEE vs BMR — what is the difference?
BMR is what you burn at complete rest; TDEE is BMR plus everything else — walking, working, training, even digesting food. Diet targets should be set against TDEE, not BMR.
How fast can I safely lose weight?
A 500 kcal daily deficit works out to roughly 0.5 kg (about 1 lb) per week, which is the pace most guidelines consider sustainable. Larger deficits work but cost more muscle and are harder to keep.
Is this medical advice?
No. Mifflin-St Jeor with standard activity multipliers, which is guidance rather than measurement. A medical condition or a medication that affects metabolism changes this substantially, and no formula accounts for it.
Is my data stored or sent anywhere?
No. Your height, weight and age stay on your device.
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