Resting metabolism from lean mass

If you know your body fat, this is a more accurate way to estimate resting energy than formulas that only use height, weight and age.

Your details

Weight
Body fat

No body fat number? The body fat calculator gives you one from a tape measure.

Your resting energy (Katch-McArdle)

1,580

kcal a day at complete rest

  • Cunningham formula1,730 kcal
  • Lean mass used8 st 12 lb

This is what your body burns doing nothing at all, before any movement. It is only as good as your body fat number, so a rough body fat gives a rough answer.

The working

Katch-McArdle

Lean tissue burns most of your resting energy, so this formula starts there:

370 + 21.6 × lean mass in kg

At 11 st 11 lb (74.8 kg) and 25% body fat, lean mass is 74.8 × 0.75 = 56.1 kg. So resting energy is 370 + 21.6 × 56.1 = 1,582 kcal a day.

Compared

How it differs from Mifflin-St Jeor

Our calorie calculator uses Mifflin-St Jeor, which needs only your sex, age, height and weight. It is the best general formula, but it assumes average body fat. If you are very muscly or carry more fat than average, the lean mass route can be closer.

What it is not

Resting is resting

This is energy for breathing, circulation and keeping warm while lying still. Your everyday number is usually 20% to 70% higher once you move about. The calorie calculator adds that part.

Questions

Common questions

What is Katch-McArdle?

A resting energy formula built on lean body mass, popularised by exercise scientists Frank Katch and William McArdle. It is widely used in sport.

Is Cunningham better?

Cunningham (500 + 22 × lean mass) was fitted to active people and usually gives a slightly higher number. Both are estimates.

Why does muscle raise resting energy?

Muscle and organs use more energy at rest than fat does, so two people of the same weight can have different resting needs.

Sources

Last checked 21 October 2026. Spotted something wrong? Tell us and we will fix it.

If your weight is on your mind

Talk to your GP if your weight has changed a lot without trying, or if it is worrying you. If food or your body feels hard to think about, Beat has a free helpline on 0808 801 0677 (England, weekdays 3pm to 8pm).

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