The basal metabolic rate indicates the number of calories needed to perform basic metabolic functions, such as keeping vital organs functioning. Calculation of the basal metabolic rate should be done when the digestive system is not active. For a more precise calculation, it would therefore be necessary to fast in the previous 12 hours.
EQUATIONS FOR CALCULATING THE BASAL METABOLIC RATE
The following equations are all suitable for calculating basic metabolism. The most commonly used equation is the Mifflin-St Jeor equation (the calculator on this page also uses it).
E = age
G = percentage of body fat (used only in the Katch-McArdle formula)
H = height in centimeters
P = weight in kilograms
- Mifflin-St Jeor equation for men: Basal metabolic rate = 10P + 6.25H – 5E + 5
- Mifflin-St Jeor equation for women: Basal metabolic rate = 10P + 6.25H – 5E – 161
- Updated Harris-Benedict Equation for Men: Basal Metabolic Rate = 13.397P + 4.799H – 5.677E + 88.362
- Updated Harris-Benedict Equation for Women: Basal Metabolic Rate = 9.247P + 3.098H – 4.330E + 447.593
- Katch-McArdle formula: Basal metabolic rate = 370 + 21.6 (1 – G) P.
WHAT FACTORS AFFECT BASAL METABOLIC RATE?
Each of the variables mentioned above influences the calculation of the basal metabolic rate. The only variables that can be influenced are weight and body fat percentage. Muscle mass also affects the basal metabolic rate, although it is not mentioned in the equations.
For example, two people who are of the same height, age, weight, and gender but different muscle mass will have, according to the equations, the same basal metabolic rate. But we know that this is not true: those with greater muscle mass need more calories to maintain homeostasis, as muscles require energy. That’s why the Katch-McArdle formula uses body fat percentage and not gender (body fat is a more accurate indicator of an individual’s muscle mass than gender is).
From the calculation, you can easily guess that losing weight decreases the basal metabolic rate. This means that as you lose weight, your body needs fewer and fewer calories to maintain homeostasis. This fact has implications in terms of the strategies used to lose weight.
HOW TO USE THE BASAL METABOLIC RATE CALCULATION TO LOSE WEIGHT
Calculating your basal metabolic rate is a good place to start planning a weight loss strategy. Once you have established the minimum amount of calories needed to maintain your weight, you can guess that consuming more calories will lead to weight gain.
The basal metabolism, however, does not take into account the physical activity you carry out, since the calculation is carried out at rest and possibly after hours of fasting. If you exercise, even at a basic level, it increases the energy your body needs to maintain homeostasis.
As you lose weight, your basal metabolic rate calories go down. This means that if you want to continue losing weight, you need to further reduce your calorie intake. Here is an example:
A 35-year-old woman who weighs 75 kg and is 169 cm tall has a basal metabolic rate of 1515 calories per day. If you lose 10 kg, your basal metabolic rate drops to 1390 calories per day. This means that if you want to continue to lose weight you will need to reduce your calorie intake further.
If, on the other hand, you maintain a constant calorie intake regardless of weight, your weight loss will eventually stall (unless that constant calorie intake is extremely low, which is not recommended for those who want to lose weight in a healthy and lasting way).
RESTING METABOLIC RATE VS. BASAL METABOLISM
Resting metabolic rate and basal metabolic rate are often used interchangeably, but incorrectly. The resting metabolic rate is not calculated in a completely balanced situation, which makes it easier to measure, because it is not necessary to reach a condition of total inactivity (for example through fasting).
IS THE CALCULATION OF THE BASAL METABOLIC RATE RELIABLE? WHAT SCIENCE SAYS
Basal metabolic rate calculators are a great starting point for embarking on a weight loss or weight gain journey. But each individual is different. For this reason, although it is an accurate indicator at the population level, basal metabolic rate may not be accurate at the individual level. Furthermore, science has shown variations in the reliability of basal metabolic rate when measured on non-Western or non-European populations. [ 1 ] A recent Cambridge University study found that basal metabolic rate tends to be overestimated in some populations; another paper published in The American Journal of Clinical Nutrition found that gender and age have a limited effect on basal metabolic rate, while lean body mass is a more reliable indicator.
As mentioned, the calculation of the basal metabolic rate is a valid starting point. However, if you are looking for the most effective way to (5 Popular Exercises which Helps to Fit Our Body in Age of 50 plus. do You Know?) to lose weight in a healthy and lasting way, contact a qualified professional.