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 the finance sector. In the field of health, it is a method for calculating the basic metabolism of the human body, 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, method and practical tools in this article!
Calculating basal metabolic rate: a reference in dietetics
Basal metabolic rate: 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 great deal of information from their patients, such as :
- state of health
- lifestyle
- eating habits,
in order to offer them personalised monitoring and tailored services.
Resting energy expenditure(REE) and the level of physical activity (NAP) are essential criteria in dietetic practice, particularly for determining actual energy expenditure.
By calculating basal metabolic rate, using Black's formula in particular, 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 the basal metabolic rate, such as :
- the Harris-Benedict formula,
- the Harris-Benedict formula improved by Roza and Shizgal,
- the Black et al. formula, which are among the most widely used.
💡 The Black et aI. formula, which we will understand in detail, is one of 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
The research by Black and his colleagues was carried out on 574 subjects aged between 2 and 95. The aim of the study was to describe the average levels of energy consumed by populations in industrialised societies.
It also aimed to understand the influence of weight, height, age and sex 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 sexes, have different basal metabolisms. There is therefore 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 the estimated 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 in terms of daily energy requirements, which vary according to the subject's level of activity. He recommends :
- for a sedentary person, to expend at least 1.2 times their basic metabolism per day,
- for extremely active or athletic people, a maximum of 4.5 times their basal metabolic rate.
Monitoring your basal metabolic rate: practical tools
Online calculation tools 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 incorporates Black's formula?
Nutrium online nutrition software automatically calculates basal metabolic rate using Black's formula, based on your patients' information. If you wish, you can opt for another formula, such as the Harris-Benedict formula.
Nutrium
What's more, the tool makes it easier to monitor your patients and assists you in your day-to-day consultations: nutritional calculations, setting targets, drawing up eating plans, and other features to boost efficiency. Its mobile application is free for patients, giving them all their practitioner's recommendations at their fingertips.
For its part, Panda 3.0, a dietetic software package designed by professional dieticians, presents itself as a Programme d'Analyse Nutritionnelle Diététique et Alimentaire (Programme for Dietetic and Food Nutritional Analysis). It is designed for professionals working 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