Basal metabolism rate is the minimal amount of energy we spend maintaining our vital functions at rest (blood circulation, digestion of food, respiration).
Basal Metabolic Rate Definition
Basal metabolic rate is the amount of heat expended per unit of body weight per day. It is usually measured first thing in the morning on an empty stomach. The basal metabolic rate depends on gender, age, weight, genetics, thyroid function, and several other factors.
Basal metabolism is the minimum amount of energy required by the human body to maintain life and activity at rest at an ambient temperature of 68 °F. This energy is spent on breathing, circulation, digestion, and maintaining body temperature. It is determined by the amount of heat per unit mass of the human body per day.
Metabolism and Basal Metabolism: Fundamentals of Functioning
Metabolism is a complex metabolic process that converts food into energy, giving our body the ability to function. All our life activity is associated with energy consumption, which is produced by 4 categories of metabolism:
- Food thermogenesis or TEF (Thermic effect of food). It includes the processing and digestion of food. This process consumes about 10% of the total energy expended.
- Thermogenesis during active exercise or TEE (Thermic effect of exercise). In simple terms, this is energy consumption from training, which makes up 5% -15% of total energy consumption.
- Thermogenesis of physical activity without exercise or NEAT (Non-exercise activity thermogenesis) – includes simple body movements (changing posture, walking, and even just standing). With this activity, energy consumption is very significant and, in some cases, can be equated to intense physical activity.
- Metabolism at rest or basal metabolism. This process contributes to the maintenance of general vital activity at rest and spends from 50% to 75% of total energy.
Energy consumption should be understood as burning calories, and if everything is very clear with the first 3 processes, the last one seems somehow mysterious. But in fact, everything is simple. Basal metabolic rate or BMR is the minimum amount of energy (calories) expended by the human body to sustain its own life at rest. This includes:
- circulation;
- breathing;
- brain activity;
- cell repair;
- protein synthesis, etc.
You can also find RMR (Resting metabolic rate), which means metabolism at rest. The difference between BMR and RMR is relevant only for clinical research, and for a general understanding of these two terms, they are actually the same.
Principles of BMR
So what is my BMR? Your personal BMR is defined as the rate at which your body converts calories into energy to support life at rest. This factor also affects weight gain or loss and determines the rate of aging.
For most people, the BMR is between 1,000 to 2,000. This means they need to consume 1,000 to 2,000 calories daily to maintain basic functions. Your basal metabolic rate is a number that indicates the number of calories you burn just lying on the couch from morning to evening.
People who eat nonstop without gaining weight are not a rule in conditions of a fast metabolism but an exception to the rules, which manifests itself due to a special confluence of accompanying processes and genetic characteristics. In other cases, the innate speed of BMR (no difference, slow or fast) is a particularly important but not decisive factor in influencing body weight. This is confirmed by numerous studies, namely:
- slow BRM may promote weight gain; and
- basal metabolic rate can peak in both slim and overweight people, while, at the same time, there is no effect of slowing down BMR due to excess weight.
Muscles burn far more calories than fat for their vital functions. Accordingly, the more muscles, the higher the BMR speed. But obese people have a larger body and more weight; thus, their basal metabolic rate is higher than non-obese people, regardless of the amount of muscle mass.
All the above facts are given for only one purpose: to convey a simple truth. Slow metabolism is not the cause of being overweight. Of course, genetics are directly involved in determining the metabolic rate, but we can easily speed it up, even just by increasing lean muscle mass. In addition, plenty of other factors directly affect the BRM’s speed, both in the fast and slow direction. These factors include:
- Age – the older we get, the slower our metabolism. This is one reason why people tend to actively gain weight with age.
- Body size and weight – the larger the person, the more calories they burn at rest;
- Ambient temperature – the colder it is, the higher the rate of BMR is, as the body actively burns calories to maintain the required body temperature.
- Physical activity – absolutely any body movement requires energy. The more you move, the more calories you burn.
- Gender. On average, men have less body fat and more muscle mass. As a result, women’s BMR levels are 3% lower than men of the same weight and height.
Basal metabolic rate affects weight gain or loss but is not the cause of obesity problems. The BMR rate is dependent on genetic predisposition, but throughout life, it can change in one direction or another.
To know your BMR, you must calculate your body’s basic metabolism. But how?
What is the Formula for Calculating BMR?
You can measure your BMR using your gender, weight, age, and height with an 80-85% accuracy, which is a very high indicator.
So, for the calculation, we need a formula and the following data:
A – body weight
B – age
C – height in cm
Let’s take the most popular and accurate formula for calculating BMR:
men: BMR = 10 x A + 6.25 x C – 5 x B + 5
women: BMR = 10 x A + 6.25 x C – 5 x B – 161
Next, we will need to multiply the resulting base metabolic index by our physical activity. The latter is divided into 5 categories:
- Passive (Complete lack of physical activity or the minimum level – BMR x 1.2);
- Minimal (Having a training process up to 3 times in a seven-day period – BMR x 1.375);
- Moderately active (the presence of a training process up to 5 times in a seven-day period – BMR x 1.55);
- Active (the presence of a training process up to 6 times in a seven-day period – BMR x 1.725);
- Overactive (if your work is associated with high-intensity physical activity, there are daily workouts, or you are a professional athlete – BMR x 1.9).
How to calculate BMR example:
Example 1: you are a female with a height of 170 cm, age 27, a weight of 52 kg, and minimal physical activity.
10 x 52 + 6.25 x 170 – 5 x 27 – 161 = 1286.5 x 1.375 = 1769 kcal.
Example 2: you are male with a height of 175 cm, age 25, a weight of 80 kg, and moderate physical activity.
10 x 80 + 6.25 x 175 – 5 x 25 + 5 = 1773.75 x 1.55 = 2749 kcal.
The final number represents the basic metabolic index — your daily energy requirement. This is the number of calories your body needs each day to maintain a consistent weight.
In order to lose 0.6 kg per week, the calorie deficit should be 600. Using the BMR for the female in example 1, we have 1769 kcal. We subtract the 600 calories and get 1169 kcal, which is noticeably below the acceptable level. In this case, the only correct way to lose weight is to increase physical activity and not exhaust the body with hunger.
Knowing exactly how many calories you burn during the day at rest makes it much easier to pave the way to the body of your dreams. Calculate your personal basal metabolic rate and work on the long-awaited transformation of your body.
