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Katch-McArdle BMR calculator

Katch-McArdle drops height, age and sex entirely and works from lean mass, on the grounds that fat is metabolically quiet.

%
Basal metabolic rate
1610kcal/day
= Exact BMR (Katch-McArdle)
Lean body mass
57.40
Daily energy needs
2214 kcal/day
Show the working
  1. Weight = 70
  2. Body fat = 18
  3. Activity level = 1.375
  4. Lean body mass = 70 * (1 - 18/100) = 57.4
  5. Basal metabolic rate = 370 + 21.6 * 57.4 = 1609.84
  6. Daily energy needs = 1609.84 * 1.375 = 2213.53

Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.

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    The formula

    • BMR = 370 + 21.6 x lean body mass in kg

    Accuracy depends entirely on the body fat figure, and consumer scales measuring it by bioimpedance are unreliable.

    This is a population formula, not a diagnosis. Individual metabolism, body composition and medical history all move the real answer, so treat the number as a starting point and talk to a clinician about anything that matters.

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