Whether sitting, walking or sleeping - we are constantly burning calories. Even at rest, the body uses energy to maintain vital functions. The basal metabolic rate is relevant for this. This varies from person to person and is determined by certain factors. (1) There are now various formulas for calculating the basal metabolic rate. (2) Muscle building or losing weight is often based on the basal metabolic rate.
In this article we will explain to you what the basal metabolic rate is and how it is influenced. We will show you how you can easily calculate it yourself using different formulas. Finally, we give you valuable tips and tricks on when and how you should increase or reduce your basal metabolic rate.
the essentials in brief
- The total human energy consumption consists of three components. One component is the basal metabolic rate. It accounts for the largest share at around 60 to 70 percent.
- The basal metabolic rate is the amount of energy that a healthy person burns in the morning, sober, relaxed and lying down at a comfortable ambient temperature. It regulates homeostasis, the heart and respiratory muscles and the activity of the intestine.
- There are now various formulas for calculating the basal metabolic rate. The Harris-Benedict formula, which is influenced by age, weight, gender and height, is particularly common.
Calculating basal metabolic rate: What you should know
Even when we are at rest, we use energy to keep our heart beating and our digestion taking place, for example. Our energy balance is a complex matter made up of a wide variety of components. The total energy consumption of a person is divided into basal metabolic rate (GU), diet-reduced thermogenesis (DIT) and activity-induced thermogenesis (AIT). (3)
It is generally assumed that the basal metabolic rate represents the largest proportion. (3) Its share in the total energy turnover is about 60-70 percent. (4)
In certain situations or conditions we sometimes use more and sometimes less energy. (5) It is optimal when our energy intake is adequate to the energy expenditure. (5) Exceptions, however, are muscle building and the intention of losing weight.
What is the basal metabolic rate?
The basal metabolic rate, also called basal energy turnover or basal metabolic rate (BMR), stands for the total energy that is essential for maintaining physiological homeostasis. (1,2) Homeostasis is the self-regulation of a biological system and permanently restores the physiological balance. (6) The basal metabolic rate is around 7000 kJ per day. (7)
The basal metabolic rate maintains homeostasis.
The basal metabolic rate is the amount of energy that a healthy person burns in the morning, sober, relaxed and lying down at a pleasant ambient temperature. (7) Most of the basal metabolic rate is released in the form of heat. (7) Furthermore, the basal metabolic rate takes care of the heart and respiratory muscles, the motility of the intestines, muscle tone and continuous cell renewal and synthesis. (2).
The term "resting energy expenditure" is also often encountered, which is comparable to the basal metabolic rate, but is measured in a less standardized way. (2.5) Resting energy expenditure is approximately 10 percent higher than basal metabolic rate. (5)
The daily energy turnover then results from the sum of the basal turnover and the work turnover. (7) The work turnover is the amount of energy by which the energy turnover during physical activities is increased above the basal turnover. (7). As soon as the work turnover extends over a certain period of time, it is also defined as performance turnover. (7)
What is the difference between basal metabolic rate and calorie requirement?
The basal metabolic rate represents the basal amount of energy that is necessary for vital functions. The calorie requirement can also be equated with the energy requirement that is consumed through physical activities and work in addition to the basal metabolic rate. The calorie requirement is made up of the basal metabolic rate and the performance metabolic rate. (8th)
How is the basal metabolic rate calculated?
There are various well-known formulas for calculating the basal metabolic rate. Furthermore, certain standard conditions are formulated for its determination. The following standardized conditions for measurement are mentioned: (1)
- In the morning
- in mental and physical rest, lying down
- fasting (12 hours without food)
- Indifference temperature / comfort temperature is present
- normal body temperature
The basal metabolic rate is primarily determined by the fat-free body mass (lean body mass). (10) Lean mass is composed primarily of muscle, which is highly metabolically active, and tissue, which is less metabolically active. (4)
- Woman (60 kg): 1300 kcal (5400 kJ)/day
- Man (70 kg): 1700 kcal (7100 kJ)/day (10)
First of all, the basal metabolic rate (GU) can be estimated using a formula. (1) We will come back to the differences between men and women later.
- Men: GU = 100 kJ * body weight in kg
- Women: GU = 100 kJ * body weight in kg * 0.9
Another simplified formula is the following:
- Men: GU = body weight (kg) *24
- Women: GU = 0.9 * body weight (kg) *24
This is based on the assumption that one kilogram consumes around 24 calories per day on average. (11)Advantages
- simple rule of thumb
- easy to calculate
- quick overview
The Harris-Benedict formula has been established to determine the basal metabolic rate. It represents a more precise calculation method. However, it only describes the basal metabolic rate without other influencing factors such as activity and stress. (9)
|feminine||GU = 655 + (9.6 * weight in kg) + (1.8 * height in cm) - (4.7 * age in years)|
|masculine||GU = 66.5 + (13.8 * weight in kg) + (5.0 * height in cm) - (6.8 * age in years)|
Alternatively, calculations can also be made with more precise values. (1)
Female: GU = 655.096 + 9.563 * weight (kg) + 1.850 * height (cm) - 4.676 * age (years)
Male: GU = 66.473 + 13.752 * weight (kg) + 5.003 * height (cm) - 6.755 * age (years)
Woman, 56 kilograms, 30 years and 1.62 m
GU = 655.096 + 9.563 * 56 + 1.850 * 162 - 4.676 * 30 = 1350.044
Accordingly, the basal metabolic rate is approximately 1350 calories for this person.
Normal values of the basal metabolic rate according to FAO / WHO standards
The Food and Agriculture Organization of the UN (FAO) has started studies together with the WHO to calculate the necessary food resources from the basal metabolic rate and another multiplier for physical activity. (2)
|under 3 years||GU = 0.249 * body weight (kg) - 0.127||GU = 0.244 * body weight - 0.130|
|3-10 years||0.095 * body weight (kg) + 2.110||0.085 * body weight (kg) + 2033|
|10-18 years||0.074 * body weight (kg) + 2.754||0.056 * body weight (kg) + 2.898|
|18-30 years||0.063 * body weight (kg) + 2.896||0.062 * body weight (kg) + 2.036|
|30-60 years||0.048 * body weight (kg) + 3.653||0.034 * body weight (kg) + 3.538|
|over 60 years||0.049 * body weight (kg) + 2.459||0.038 * body weight (kg) + 2.755|
However, recent studies have found that there are significant deviations in age groups for individuals of different weight classes (underweight, normal weight, overweight). (2)Advantages
- more accurate calculation
- Division into age and sex classes
If you don't want to calculate your basal metabolic rate yourself, you can now find numerous free offers on the Internet that will help you.
How high is the basal metabolic rate in a woman / a man?
In women, the values of the basal metabolic rate are about 10 percent lower than in men. Therefore, the formula GU = 100 kJ * body weight (kg) * 0.9 for women resulted in the previous section. (1)
The factor 0.9 takes into account the gender-specific ratio of body fat and muscle mass. (11) The basal metabolic rate for a man weighing 70 kilograms is around 7100 kJ / day, while for a woman it is around 6300 kJ / day. (1)
The basal metabolic rate can be easily estimated or precisely calculated using various formulas. Certain factors play a role here, such as body weight. (Image source: i yunmai / unsplash)
Which factors influence the calculation of the basal metabolic rate?
Based on the elements of the formulas, you could already see that the basal metabolic rate is influenced by various factors. These are explained in more detail below:
- Diurnal fluctuations: It is assumed that these fluctuations are associated with food intake. Energy turnover is highest in the morning. (1) It is lowest at night and early in the morning.
- Physical and mental exertion: Muscular work increases energy expenditure and therefore the basal metabolic rate must be measured when the body is at rest. Mental exertion also increases energy expenditure. (1)
- Ambient and body temperature: When the outside temperature drops, the body begins to lose heat and freeze. In order to restore the balance between heat release and heat production, the muscular energy turnover is increased by freezing. (1)
- Height and weight: Height and weight affect the basal metabolic rate. Furthermore, the size and weight determine the size of the body surface through which heat is usually released. (1)
- Body composition: The more metabolically active body cell mass there is, the higher the energy expenditure. This metabolically active mass is also called fat-free mass (FFM) and is made up of the skeletal muscles, the skeleton and the internal organs. (1)
- Age: Children have a higher basal metabolic rate. They give off more heat in relation to their weight and at the same time require additional energy for their growth. (1) With increasing age, the basal metabolic rate decreases.
- Gender: The male basal metabolic rate is usually 10 to 20 percent higher than the female. (1) This is due to the size, weight and higher FFM content.
- Hormones: Certain hormones such as adrenaline, noradrenaline, progesterone and thyroxine increase the basal metabolic rate. (1)
- Diseases: Various diseases can affect the basal metabolic rate. An increase is present, for example, with fever, burns and an overactive thyroid gland. (1) If the thyroid gland is underactive, it is low.
- Other factors: Pregnancy, climatic conditions, medication, sleep, etc. also affect the basal metabolic rate. (12)
So it turns out that a variety of factors have to be taken into account in order to calculate the basal metabolic rate. Some factors are represented in the formulas, but not all are accommodated.
What role does the basal metabolic rate play in weight loss?
The basal metabolic rate also plays a major role in losing weight , since it accounts for a large part of the energy balance. First of all, almost every diet leads to weight loss and caloric restrictions result in a decrease in the basal metabolic rate. (4) This is mostly associated with a decrease in lean body mass (LBM).
Furthermore, the intention of weight loss is to lose fat mass while maintaining LBM as much as possible. (4) However, the behavior of the basal metabolic rate under weight reduction is not yet precisely known.
The basal metabolic rate also plays a central role when it comes to losing weight. However, for effective weight loss, physical activity must be combined with a calorie deficit. ( Diana Polekhina / unsplash )
If you eat less, the basal metabolic rate is down-regulated. (13) As a result, the body begins to freeze more easily, but it does not lose weight directly. (13) The change in caloric intake is also communicated to the muscles.
Due to the lower intake of calories, the body becomes more economical. The faster you lose weight, the more muscle mass is lost. (14) The reduced muscle mass then results in lower energy consumption. (14)
Due to the persistence of the diet phase, the metabolism, the basal metabolism and the performance turnover continue to be down-regulated. (13) If energy intake is not adjusted after weight loss, weight can quickly regain. Excess calories are therefore stored directly as fat.
Often caloric savings of 300 to 400 calories do not have a significant impact on weight. (13) In order to really lose weight effectively, physical activity is particularly relevant, as is increasing muscle mass. An increased resting metabolic rate is said to lead to weight loss. (16)
How can the basal metabolic rate be increased?
Since the basal metabolic rate is not a constant variable, it can also change. Since it is mainly determined by lean body mass, it increases with increasing lean mass. (15) So it increases by about three kilocalories per one kilogram of lean mass per day. (15) However, the basal metabolic rate hardly increases when it comes to enlarged fat pads.
Muscle mass can increase the basal metabolic rate.
Furthermore, the basal metabolic rate can be stimulated by physical activity. The increase in muscle mass through sport indirectly results in a long-term increase in the basal metabolic rate. (16) The performance turnover is also sustainably increased through exercise. Thus, the basal metabolic rate can be increased with strength training.
In addition, stress, sweating, fever and low temperatures lead to an increase in the basal metabolic rate. (15)
- Iodine: stimulates the metabolism
- Proteins: Proteins increase the basal metabolic rate
- Omega 3 fatty acids: are important for many bodily functions, including metabolism
- Hotness: ensures a better metabolism and increased body temperature
- Alternation of hot and cold: in order to keep the body temperature in balance, the body has to be active and consumes energy - the basal metabolic rate is increased
These are just a few of the highlights of increasing the basal metabolic rate. Above all, physical activity plays a central role.
What is the power turnover and how is it calculated?
Power expenditure is another component of energy expenditure. It defines the additional activities in addition to the basal metabolic rate in order to maintain bodily functions. (17) Consequently, the performance metabolic rate consists of the basal metabolic rate supplemented by the physical activity factor (Physical Activity Level, PAL). (17)
For the total turnover, the basal turnover must be supplemented by the performance turnover based on PAL factors. These factors are broken down into different value ranges. (Image source: Green Chameleon/unsplash)
The Physical Activity Level (PAL) results from multiplying the degree of workload or physical activity in leisure time by the basal metabolic rate. In addition, physical activity is differentiated into different groups. (18)
|1.2||only sitting, lying down||old, frail people|
|1.4-1.5||almost always sitting, little/no physical activity||desk job|
|1.6-1.7||predominantly sitting, additional standing/walking activity||Laboratory technicians, drivers, students|
|1.8-1.9||mostly walking/standing||Sellers, waiters, craftsmen, housewives/housemen|
|2.0-2.4||physically demanding professional work||Construction workers, farmers, competitive athletes|
If one is active in sports or engages in certain leisure activities (30-60 minutes, 4 to 5 times a week), then 0.3 PAL units per day are added to the values given in the table.
Woman (60 kilograms, 40 years), office worker, active in sports 4 to 5 times a week (30 to 60 minutes)
Resting energy expenditure * PAL = 1302 kcal/day * 1.7 = 2213 kcal/day
The resting energy consumption of 1302 is multiplied by the PAL factor of 1.7. The total energy is then 2213 kcal/day.
What alternative calculations are there besides calculating basal metabolic rate?
Anyone who deals with their body, their diet and weight loss has probably already dealt with other calculations. For example, the calorie requirement and normal/underweight/overweight can be determined. We would like to briefly present further calculations to you in the following section:
- Performance turnover: The performance turnover supplements the basal turnover with the physical activities using the PAL factors. The calculation has already been shown above.
- Total turnover: The basal turnover and the performance turnover result in the total turnover. Thus, the total turnover corresponds to the amount of energy that is required daily to maintain one's own body weight. The total calorie requirement is calculated.
- Calorie requirement: Calorie requirement calculators are based on the duration of sleep, work activity, duration and type of sport and your own body weight.
- Body Mass Index (BMI): This is an evaluation of weight in relation to height. BMI is calculated as follows: BMI = body weight / (height)².
Of course there are other components and formulas. In the meantime, however, many calculators are offered free of charge by health insurance companies, for example, if you are not sure about the calculation. Nevertheless, you have now received a fairly comprehensive overview of the most important formulas.
So you have now learned that the basal metabolic rate is an essential part of our energy balance and accounts for a large proportion. Thanks to him, the necessary bodily functions continue to be carried out in complete calm.
You can proceed in different ways when calculating it. The basal metabolic rate can be estimated with simple formulas or calculated more precisely with the Harris-Benedict formula. The FAO/WHO standards also serve as a guide.
The basal metabolic rate is essentially influenced by your age, gender, height and body weight. There are also other standardized conditions. Once you have the formula, all you have to do is enter your personal information to determine your basal metabolic rate.
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