Blog · 2 min · figures checked on 9 November 2026
How to work out your basal metabolism and your calories
By Nicolas Papon, founder of Live For Fit ·
If you know your body fat, the Katch-McArdle formula (Cunningham) is the best fit, because it starts from your lean mass. Otherwise, use the Mifflin-St Jeor formula. You then multiply by your activity level.
What the research says
Cunningham (1991) estimates resting metabolism from lean mass. It is the basis of the formula known as Katch-McArdle.
Mifflin, St Jeor et al. (1990) propose an equation based on weight, height, age and sex, useful when body fat is unknown.
What Live For Fit does
At Live For Fit: The app uses Katch-McArdle when your body fat is known, and Mifflin-St Jeor otherwise, then an activity factor between 1.2 and 1.9.
At Live For Fit: The calculation is only a starting point: each week, your real weight curve corrects your calories.
We publish Live For Fit. This information does not replace medical advice.