Black et al. formula: a calculation method for basal metabolic rate
The Black formula should not be confused with the Black-Scholes model or formula used in finance. In the field of health, it is a method for calculating the basic metabolism of the human organism, based on age, weight and height.
As a nutrition or dietetics professional, what do you need to know about Black's formula? How do you use it and what tools do you need to calculate your basal metabolic rate? Explanations, methods and practical tools in this article!
Calculating basal metabolic rate: a reference in dietetics
Basal metabolism: definition
Basal metabolic rate ( BMR) is the basic energy expenditure of the human body. It refers to the body's minimum energy requirements in the absence of any activity to ensure its vital functions (respiratory, digestive, cerebral, maintenance of body temperature, etc.).
An essential calculation for nutritionists and dieticians
Nutrition and dietetics professionals rely on a wealth of information from their patients, such as :
- state of health
- lifestyle,
- eating habits,
in order to offer personalized follow-up and adapted services.
Resting energy expenditure(REE) and physical activity level (PAL) are essential criteria in the practice of dietetics, particularly for determining actual energy expenditure.
By calculating basal metabolic rate, in particular using Black's formula, they can estimate their patients' daily energy expenditure (DEJ).
They are then able to provide specific recommendations, and draw up tailored dietary plans to help them achieve their goals (weight loss, muscle mass gain, etc.).
The basal metabolic rate formula
There are various formulas for calculating basal metabolic rate, such as :
- the Harris-Benedict formula,
- the Harris-Benedict formula improved by Roza and Shizgal,
- the Black et al. formula, among the most widely used.
💡 The Black et aI. formula, which we will understand in detail, is among those recommended by the Association Française des Diététiciens Nutritionnistes (AFDN) in the dietitian's clinical practice.
Basic metabolism and Black's formula
Background to Black's formula
Research by Black and colleagues was carried out on 574 subjects, aged between 2 and 95 years. The aim of the study was to describe the average levels of energy consumed by populations in industrialized societies.
It also aimed to understand the influence of weight, height, age and gender on this energy expenditure. The work was published in 1996.
Method for calculating basal metabolic rate
To calculate basal metabolic rate using Black's formula, the following factors are taken into account:
- gender
- weight
- height
- and age.
ℹ️ People of the same age, weight and height, but of different genders, have different basal metabolisms. So there's one calculation for men and another for women.
Here are the equations to be used to calculate it:
Female: 0.963 × P0 .48 × T0 .5 × Â-0 .13
Male: 1.083 × P0 .48 × T0 .5 × Â-0 .13
This gives an estimate of resting energy expenditure in kJ/day.
Black et al. formula: example
► For a woman, whose characteristics are as follows:
- 58 kg
- 1,65 m
- 38 years old
For a result in kcal, the calculation will be as follows:
[1.083 × 580 .48 × 1. 650.50 × 38-0 .13 ] x (1,000/4.1855) = 1,293.2 kCal
▶︎ For a man with the following characteristics :
- 80 kg
- 1,85 m
- 42 years old
For a result in kcal, the calculation would be as follows:
[1.083 × 800.48 × 1. 850.50 × 42-0 .13 ] x (1,000/4.1855) = 1,773.8 kCal
In his study, Black specifies the limits of the human body's daily energy requirements, which vary according to the subject's level of activity. He recommends :
- a sedentary person needs to expend at least 1.2 times his or her basic metabolism per day,
- for extremely active or athletic people, to expend a maximum of 4.5 times their basal metabolic rate.
Tracking your basal metabolic rate: practical tools
Online calculators can automatically give you the results, by entering the gender, age, weight and height criteria mentioned.
While calculators are useful on an occasional basis, they are not directly linked to the patient file, and encourage the use of several tools.
Why not use software designed specifically for dieticians and nutrition professionals, which integrates Black's formula?
For example, Nutrium online nutrition software automatically calculates basal metabolic rate using Black's formula, based on your patients' data. If you wish, you can opt for another formula, such as the Harris-Benedict formula.
© Nutrium
What's more, the tool facilitates patient follow-up and assists you in your day-to-day consultations: nutritional calculations, goal-setting, food planning, and other efficiency-enhancing features. Its mobile application is free of charge for patients, giving them all their practitioner's recommendations at their fingertips.
For its part, Panda 3.0, a dietetics software designed by professional dieticians, presents itself as a Programme d'Analyse Nutritionnelle Diététique et Alimentaire. It is designed for professionals in private practice as well as clinicians, nutritionists and researchers.
Nutrytion
This analytical tool can be used to quickly carry out dietary assessments, evaluate nutritional intakes, calculate food rations or evaluate recipes.
What tools and methods do you use to monitor your patients' basal metabolisms?
Article translated from French