Calorie calculation is carried out using the Mifflin St Jeor (if fat percentage is unknown) and Katch-McArdle (if fat percentage is known) formulas, developed in 1990 and 1991, respectively (
1,
2).
Both formulas have been tested for their accuracy many times (
3,
4,
5,
6,
7,
8), relative to the gold standard - gas calorimetry. In both the general population and athletes, formulas have shown that they often underestimate real caloric expenditure by ≥10%.
However, gas colorimetry is an expensive, time consuming, and scarcely available test, and formulas like Mifflin St Jeor and Katch-McArdle are quick calorie calculation methods that are regularly used by nutritionists and athletes to provide a starting point for nutrition planning.