BX. Equations for calculating the basal metabolic rate

Metabolism concept. Basic and general metabolism

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Article topic:	Metabolism concept. Basic and general metabolism
Rubric (thematic category)	Education

Metabolism and energy- is a set of physical, chemical and physiological processes of absorption of nutrients in the body with the release of energy. In metabolism (metabolism), there are two interrelated but multidirectional processes - anabolism and catabolism. Anabolism is a set of processes of biosynthesis of organic compounds, components of cells, organs and tissues from absorbed nutrients. Catabolism- these are the processes of breaking down complex components into simple substances that provide the energy and plastic needs of the body. The vital activity of the body is provided by energy due to anaerobic And aerobic catabolism of proteins, fats and carbohydrates supplied with food.

Basic exchange It is customary to call the amount of energy that the body spends at complete muscular rest, 12-14 hours after eating and at an ambient temperature of 20-22 ° C. Basic metabolism maintains the life of the body at the lowest level of activity of the nervous system, heart, respiratory apparatus, digestion, endocrine glands, excretory processes, and rest of skeletal muscles. Even in conditions of complete rest, metabolism in cells and tissues does not stop - the basis of life of the body. The indicator of basal metabolism is heat production in kcal per 1 hour per 1 kg of body weight and is equal to 1 kcal.

The leading role in metabolism belongs to the functional state of the nervous system, its regulation of the level of metabolism in organs and tissues, maintaining the relative constancy of the composition of proteins, the chemical composition of blood, temperature, etc., relatively independently of changes in the external environment, under different living conditions. The activity of the endocrine glands also significantly affects the basal metabolism. For example, basal metabolism increases with an increase in the function of the thyroid gland and, on the contrary, decreases with a decrease in its functions and the pituitary gland. With an increase in body temperature by 1 °C, basal metabolism increases on average by 10%. In cold climates, basal metabolism increases, and in hot climates it decreases by 10-20%. During sleep, as a result of relaxation of skeletal muscles, it decreases to 13%. During fasting, the basal metabolism decreases. From 20 to 40 years, basal metabolism is maintained at approximately the same level, and then gradually decreases: in men to 7%, and in women to 17%.

General metabolism- occurs under normal living conditions. It is significantly higher than the basal metabolism and depends mainly on the activity of skeletal muscles, as well as an increase in the activity of internal organs. The kilocalories expended in excess of the basal metabolism are called motor calories. The more intense the muscle activity, the more motor calories and the higher the overall metabolism. During mental work, the overall metabolism increases slightly - by 2-3%, and if mental work is accompanied by muscle activity - by 10-20%.

A large increase in metabolism also occurs during the digestion of food, which is referred to as its specific dynamic action. Since the digestion of proteins requires a particularly large expenditure of energy, the specific dynamic effect of proteins is especially great. On average, after eating protein foods, basal metabolism increases by 30-37%, and after eating fats and carbohydrates by 4-6%.

Metabolism concept. Basic and general exchange - concept and types. Classification and features of the category "The concept of metabolism. Basic and general metabolism" 2017, 2018.

All food substances have a certain amount of energy. The body is called an energy transformer, because specific transformations of nutrients constantly occur in it, leading to the release of energy and its transition from one type to another. The relationship between the amount of energy received from food and the amount of energy expended is called energy balance of the body. To study it, it is necessary to determine the energy value of food.

Studies have shown that each gram of polysaccharides and proteins provides 17.2 kJ. When a gram of fat breaks down, 38.96 kJ is released. It follows that the energy value of different food products is not the same and depends on what nutrients the product contains. So, for example, the energy value of nuts turns out to be equal to 2723.5 kJ, butter - 3322.2 kJ, etc. The energy value of nutrients does not always coincide with their physiological value, because the latter is still determined by the ability to assimilate. Nutrients of animal origin are absorbed better than those of plant origin.

The amount of energy released in the body depends on the chemical transformations of substances in it, i.e., on metabolic processes. It follows that the amount of heat generated by the body can serve as an indicator of metabolism. Determining the amount of heat, i.e., the number of calories released by the body, gives the entire amount of energy transformations in the form of the final thermal result. This method of determining energy is called direct calorimetry. Determination of the number of calories by direct calorimetry is carried out using a calorimetric chamber, or calorimeter.

All these determinations can be made much more simply by studying gas exchange. Determining the amount of energy released by the body by studying gas exchange is called indirect calorimetry. Knowing that the entire amount of energy released in the body is the result of the breakdown of proteins, fats and carbohydrates, knowing also how much energy is released during the breakdown of these substances, and how much of them has undergone breakdown over a certain period of time, we can calculate the amount of energy released.

A distinction is made between general metabolism and basal metabolism. Basic exchange is the energy expenditure of the body under resting conditions associated with maintaining the minimum level of metabolic processes necessary for the functioning of cells. Basal metabolism is determined in a state of muscle rest - lying down, 12 - 16 hours after eating at a temperature of 18 - 20°C. Under these conditions, energy is spent on heart function, breathing, maintaining body temperature, etc. But this energy expenditure is small. The main costs in determining basal metabolism are associated with biochemical processes that always take place in living cells. The basal metabolic rate ranges from 4,200 to 8,400 kJ per day for men and from 4,200 to 7,140 kJ for women. On average, in a middle-aged person, the basal metabolism is 4187 J per 1 kg of weight per hour or 7140 - 7560 thousand J per day. In children 8–9 years old, the basal metabolism is 2–2.5 times higher than in an adult.

The smaller the child, the more energy is spent on his growth. Thus, at the age of 3 months, energy consumption is 36%, at 6 months – 26%, 10 months – 21% of the total energy value of food.

In preschool and primary school age, there is a correspondence between the intensity of the decrease in basal metabolism and the dynamics of growth processes: the greater the rate of relative growth, the more significant the changes in resting metabolism.

The basal metabolic rate in girls is slightly lower than in boys. This difference begins to appear in the second half of the first year of life.

The second component of the body's energy expenditure after the main metabolism are the so-called adjustable energy costs. They correspond to the need for energy used for work above the basal metabolism. Any type of muscular activity, even changing body position (from a lying position to a sitting position), increases the body's energy consumption. The change in energy consumption is determined by the duration, intensity and nature of muscle work. The more intense the muscle load, the more significant the increase in metabolism. In this regard, workers of different professions spend different amounts of energy per day (from 12,600 to 21,000 kJ). Mental work causes a slight increase in metabolism: only 2 - 3%. Any emotional excitement inevitably leads to an increase in metabolism. Metabolism also changes under the influence of food intake. After eating, metabolism increases by 10–40%. The effect of food on metabolism does not depend on the activity of the gastrointestinal tract; it is due to the specific effect of food on metabolism. In this regard, it is customary to talk about the specific dynamic effect of food on metabolism, meaning by this its increase after eating.

General energy metabolism is the sum of basal metabolism, work gain and the energy of the specific dynamic action of food. Work gain is energy expenditure on physical and mental work. Based on the nature of production activities and energy consumption, the following population groups are distinguished:

1. Persons of mental work (teachers, students, doctors, etc.). Their energy consumption is 2200-3300 kcal/day.

2. Workers engaged in mechanized labor (assemblers on a conveyor belt). 2350-3500 kcal/day.

3. Persons engaged in partially mechanized labor (drivers, turners, mechanics). 2500-3700 kcal/day.

4. Those engaged in heavy non-mechanized labor (loaders). 2900-4200 kcal/day.

The specific dynamic effect of food is energy consumption for the absorption of nutrients. It is most pronounced in proteins. Less in fats and carbohydrates. In particular, proteins increase energy metabolism by 30%, and fats and carbohydrates by 15%.

Physiological basis of nutrition. Power modes

Depending on age, gender and profession, the consumption of proteins, fats and carbohydrates should be:

In the last century, Rubner formulated the law of isodynamics, according to which food substances can be interchanged in their energy value. However, it is of relative importance, since proteins that perform a plastic role cannot be synthesized from other substances. The same applies to essential fatty acids. Therefore, a balanced diet of all substances is required. In addition, it is necessary to take into account the digestibility of food. This is the ratio of nutrients absorbed and excreted in feces. Animal products are the easiest to digest. Therefore, animal protein should make up at least 50% of the daily protein diet, but fats should not exceed 70% of the fat.

By diet we mean the frequency of meals and the distribution of its calorie content for each meal. With three meals a day, breakfast should account for 30% of the daily calorie intake, lunch 50%, dinner 20%. The interval between breakfast and lunch should not exceed 5 hours. Dinner should be at least 3 hours before bedtime. Meal times should be constant.

Exchange of water and minerals

The water content in the body is on average 73%. The body's water balance is maintained by equalizing the water consumed and excreted. The daily need for it is 20-40 ml/kg of weight. About 1200 ml of water comes with liquids, 900 ml with food and 300 ml is formed during the oxidation of nutrients. Minimum water requirement 1700 ml. With a lack of water, dehydration occurs and if its amount in the body decreases by 20%, death occurs. Excess water is accompanied by water intoxication with central nervous system stimulation and convulsions.

Sodium, potassium, calcium, magnesium, chlorine are necessary for the normal functioning of all cells. In particular, they provide mechanisms for the occurrence of membrane potential, action potentials, regulation of transmembrane metabolism, etc. The daily requirement for sodium and potassium is 2-3 g, calcium 0.8 g, chlorine 3-5 g. Calcium is necessary for the formation of the bone skeleton . In addition, it is needed for blood clotting, regulation of cellular metabolism, generation of action potentials and muscle contraction, etc. The bulk of phosphorus is also concentrated in the bones. At the same time, it is part of the phospholipids of membranes and participates in metabolic processes. The daily requirement for it is 0.8 g. Most of the iron is contained in hemoglobin and myoglobin. Iron ensures the binding of oxygen. Fluoride is part of tooth enamel. Sulfur in proteins and vitamins. Zinc is a component of a number of enzymes and insulin. Cobalt and copper are essential for erythropoiesis. The need for all these microelements ranges from tens to hundreds of mg per day.

The level of metabolism in a person's natural life is called general exchange. When performing physical and mental labor, changing posture, emotions, and after consuming food, metabolic processes become more intense. The muscles most involved in this process contract. Moreover, the state of skeletal muscles mainly affects the intensity of metabolism in some other physiological conditions. Thus, even when solving a mathematical problem, the tonic tension of the skeletal muscles increases. At the same time, in the cells of the central nervous system themselves, the activity of metabolic processes changes, but not to such an extent as to significantly affect the level of energy consumption of the whole organism. At the same time, if mental work is accompanied by emotional stress, the exchange is activated to a greater extent. This is due to an increase in the formation of a number of hormones that enhance metabolic processes.

Specific dynamic action of food

An increase in metabolism is observed for a fairly long time (up to 10-12 hours) after eating. In this case, energy is spent not only on the actual process of digestion, secretion, motility, absorption). It turns out the so-called specifically dynamic action of food. It is mainly due to the activation of metabolic processes by digestive products. This effect is greatest when protein is supplied. After just 1 hour and over the next 3-12 hours (the duration depends on the amount of food consumed), the activity of energy production processes increases to 30% of the level of basal metabolism. With the intake of carbohydrates and fats, this increase is no more than 15%.

Effect of temperature

The intensity of metabolic processes also increases when the ambient temperature deviates from a comfortable level. The greatest changes in metabolic rate occur with decreasing temperature, since in order to maintain a constant body temperature, energy of other types is converted into heat.

Energy exchange during work

The greatest increase in energy consumption is due to skeletal short-lived muscles. Therefore, under normal conditions of existence, the level of metabolic processes primarily depends on a person’s physical activity. The adult population can be divided into five groups according to the level of general metabolism. The classification is based on the intensity of physical labor, nervous tension that arises during labor processes, individual operations, and a number of other features. As new types and forms of labor activity related to technological progress are introduced and spread, labor intensity groups must be reviewed, clarified and supplemented. Five groups of workers have been identified:

1-a - predominantly mental erasable;

2-a - light physical labor;

3rd - moderate physical labor;

4-a - heavy physical labor;

5-a - especially heavy physical labor.

The need for energy is increased in individuals whose work is characterized not only by physical, but also by neuropsychic stress. Moreover, in modern conditions its importance in all labor processes is increasingly increasing.

In women, due to the lower intensity of metabolic processes and lower muscle mass, the energy requirement is approximately 15% lower than in men.

When determining the energy needs of the adult working population, it is considered appropriate to make all calculations for three age categories: 18-29, 30-39, 40-59 years. The basis for this was some age-related metabolic features. Thus, at 18-29 years of age, the processes of growth and physical development are still ongoing. From the age of 40, and especially after 50, catabolism begins to prevail over anabolism.

When developing criteria for energy requirements for the population aged 18 to 60 years, the ideal body weight was conditionally determined: for men it is 70 kg, for women - 60 kg. Energy requirements can be calculated per 1 kg of average ideal body weight. The energy requirement per 1 kg of ideal weight for men and women is almost the same and is: for the 1st group of labor intensity - 167.4 kJ (40 kcal), for the 2nd - 179.9 kJ (43 kcal), for 3 1st - 192.5 kJ (46 kcal), for 4th - 221.7 kJ (53 kcal), for 5th - 255.2 kJ (61 kcal).

Regulation of energy metabolism

The body must constantly coordinate the metabolic needs of the whole organism with the needs of its individual organs and cells. This is achieved through the distribution of absorbed nutrients between them, as well as the redistribution of substances from the body’s own depots or those formed in biosynthesis processes.

At the level of individual cells and pieces of organs, it is possible to identify the presence of local mechanisms for regulating the process of energy formation. Thus, during the performance of muscular work, the beginning of muscle contraction triggers the processes of resynthesis of the used ATP (see section 1 - “Skeletal muscles”).

Regulation of energy production processes in the body as a whole is carried out by the autonomic nervous and endocrine systems, with the latter predominant. Main regulators - thyroid hormones - thyroxine and G3, as well as A adrenal glands, stimulating these processes. Moreover, under the influence of these hormones there is also a redistribution of metabolites that are used for the formation of energy. So, during physical activity, glucose and fatty acids enter the blood from the liver and fat depots, which are used in the muscles.

The hypothalamus plays a special role in regulation, through which neuro-reflex (autonomic nerves) and endocrine mechanisms are realized. With their help, the participation of higher parts of the central nervous system in the regulation of metabolic processes is ensured. You can even detect a conditioned reflex increase in the level of energy production. Thus, in an athlete before a start, in a worker before performing the labor process, the exchange is activated. The hypnotic suggestion of performing heavy muscular work can lead to an increase in the level of metabolic processes.

Hormones of the hypothalamus, pituitary gland, pancreas and other endocrine glands affect both the growth, reproduction, development of the body, and the ratio of the processes of anabolism and catabolism. In the body, the activity of these processes is in a state of dynamic equilibrium, but at certain moments in real life, one of them is likely to prevail. (These processes are discussed in more detail in the biochemistry course.)

Research methods

Methods for assessing the body's energy balance are based on two main principles: direct measurement of the amount of heat released (direct calorimetry), and indirect measurement - determination of the amount of oxygen absorbed and carbon dioxide released (indirect calorimetry).

Most often used methods of indirect calorimetry. In this case, the amount of oxygen absorbed and carbon dioxide released is first determined. Knowing their volumes, it is possible to determine the respiratory coefficient (RK): the ratio of released CO2 to absorbed 02:

Based on the DC value, one can indirectly estimate (there are corresponding tables) the oxidation of the product, since depending on this, different amounts of heat are released. Thus, during the oxidation of glucose, 4 kcal1g of heat is released, fats -9.0 kcal1g, proteins -4.0 kcal1g (these values ​​characterize the energy value of the corresponding nutrients). The dependence of DC on the product oxidation is determined by the fact that during the oxidation of glucose, the same number of 02 molecules is used to form each CO2 molecule (DC = 1.0). Due to the fact that in the structure of fatty acids there are fewer 02 atoms per CO2 atom than in carbohydrates, during their oxidation the DC is 0.7. When consuming protein foods, the DC is 0.8.

However, when using the indirect calorimetry method, it is necessary to take into account that in real human life conditions, as a rule, mixed ingredients are oxidized. For practical use, special tables have been developed, with the help of which the amount of released energy, that is, the intensity of metabolic processes, can be determined by the amount of oxygen absorbed per unit of time and the value of DC.

Age and gender characteristics of energy metabolism

During the period of ontogenetic development, metabolic processes undergo significant changes. Until the end of puberty (Table 15), anabolic processes predominate.

Table 15. Age-related changes in general and basal metabolism

Age	General exchange, kcal1dobu	BX
		kcal1dobu	kcal1m 1dobu	kcal1kg1dobu
1 day
1 month
1 year
3 years
5 years
10 years
14 years
Adults

Since a large amount of energy is consumed to ensure age-related development, the level of basal metabolism, calculated both per unit of mass and body surface, is sharply increased. The highest rates are during the first years of life, when the basal metabolism is increased by 2-2.5 times compared to that of adults. With aging, catabolic processes predominate, which is accompanied by a gradual decrease in basal metabolism. Moreover, at all age periods, the basal metabolic rate in women is lower than in men. For example, in men aged 40 years, its average value is 36.3 kcal1m21 year, in men aged 70 - 33 kcal1m21 year; in women it is 34.9 and 31.7 kcal1m21year, respectively.

The basal metabolic rate (BMR) is the minimum number of calories required to maintain the body's vital functions in a state of complete rest. Simply put, this is the amount of energy (measured in calories) that your body will expend if you sleep all day. Basal metabolism can burn up to 70% of the total number of calories expended, but this figure varies depending on various factors (we will talk about them below). Calories are spent on various physiological processes, such as breathing, blood circulation and maintaining the desired body temperature. Naturally, the average body expends more calories than BOO.

Basic metabolism is one of the most important factors determining the intensity of metabolism in general. This indicator tells us how many calories the body needs to maintain, lose, or gain weight. The amount of basal metabolism is determined by a combination of genetic (internal) and external factors, such as:

Genetics. Some people are born with a faster metabolism, others with a slower one.
Floor. Men have more muscle mass and less body fat. This means that they have a higher basal metabolic rate.
Age. As you age, your basal metabolism slows down. After 20 year old age, every ten years this figure decreases on average on 2%.
Weight. The greater a person's weight, the greater the SBI.
Body surface area. This is the ratio of your height and weight. The greater the total surface area of ​​your body, the higher your BVR.
Tall, thin people have more BOO. If we compare a tall and short person of the same weight who consume the same number of calories to maintain their weight, we can see that after a year the taller person's weight will remain the same, but the shorter person's weight may have increased by about 7 kg.
Body fat percentage. The smaller it is, the larger the SBI. It is the lower percentage of body fat in men that is the reason why their basal metabolic rate is higher than that of women.
Diet. Fasting or sharply reducing caloric intake can reduce basal metabolic rate by 30%. Low-calorie diet for weight loss may lead to lower BOO by 20%.
Body temperature. When core body temperature increases by half a degree, BOO increases by approximately by 7%. The higher the body temperature, the faster chemical reactions occur in the body. Therefore, the BOO of a patient with a temperature of 42°C will increase approximately by 50% .
External temperature. Ambient temperature also affects basal metabolism. Exposure to cold temperatures increases BOO because the body needs to produce more heat to maintain the required core body temperature. Brief exposure to high temperatures has little effect on metabolism because... the temperature is compensated due to increased heat transfer. But prolonged exposure to heat can also increase BOO.
Hormones. Thyroxine (produced in the thyroid gland) is one of the key regulators of SBI. It speeds up the metabolic activity of the body. The more thyroxine produced, the higher the BOO. If the body produces too much of it (a condition known as thyrotoxicosis), BOO can double in size. If there is too little of it (myxedema), the VOO may decrease by 30-40% compared to the norm. Like thyroxine, epinephrine also increases BOO, but to a lesser extent.
Exercises. Exercise not only affects your weight by burning calories, but also helps increase your basal metabolic rate by increasing muscle mass.

Short-term factors affecting general metabolism

High temperature caused by inflammation, high levels of stress hormones in the body, and an increase or decrease in environmental temperature lead to an increase in BOO. Fasting, starvation or malnutrition reduces BOO. Reduced BOO may be the only side effect of the diet. A low-carb diet will not be as effective as one combined with physical activity.

Daily metabolism

The first step towards creating your own diet is to calculate how many calories do you burn per day? , i.e. Your total daily energy expenditure in calories. Knowing this value will begin the formation of your proper nutrition. Physiologists William McArdle and Frank Kachi found that the average daily energy expenditure for women in the United States is 2000-2100 calories th per day, and for men - 2700-2900 per day. But this is an average, the number of calories burned can vary significantly. For example, for athletes or people actively involved in sports, this figure will be higher. Some triathletes and athletes with extremely high loads require at least 6000 calories every day and even more!

Methods for determining calorie needs

There are various formulas you can use to determine your daily calorie needs. They take into account age, gender, height, weight, lean body mass and activity level. Any formula that takes your lean body mass (MBM) into account will give you the most accurate estimate of your energy expenditure, but even without taking into account your lean body mass (MBM), you can still get fairly accurate information.

A quick and easy method for determining calorie needs is to calculate based on your total body weight.
Fat Burning: 26-29 calories per 1 kg of body weight
Weight maintenance: 33-35 calories per 1 kg of body weight
Weight gain: = 40-45 calories per 1 kg of body weight

This is a very simple way to help you estimate your calorie needs. But there are also obvious disadvantages to this method, because it does not take into account activity level and body composition. Extremely active people may require many more calories than this formula indicates. In addition, the greater your muscle mass, the greater your calorie needs will be.

Because it does not take into account obesity, the formula may overestimate caloric needs for overweight people. For example, a 50-year-old woman who leads a sedentary lifestyle weighs 117 kg and her total body fat is 34%. She will never be able to lose weight by eating 3,000 calories every day.

Calculations based on basal metabolic rate

A much more accurate method of calculation is to determine BMR (basal metabolic rate), which uses several factors, including height, weight, age and gender. BOO is then multiplied by activity level to determine daily caloric needs. As a reminder, BOO is the total number of calories your body needs to function normally at rest. This includes heartbeat, breathing, digestion of food, creation of new blood cells, maintaining the desired body temperature and all other metabolic processes in your body. In other words, your BOO is all the energy used to keep the body alive. About 2/3 of your daily calorie requirement is BOO. The intensity of general metabolism can vary significantly from person to person, depending on genetic factors. If someone says that they can eat anything and not gain weight, this means that this person has a hereditary high intensity of general metabolism.

BOO is lowest during sleep, when the body is not processing food. It is worth noting that the greater your lean body mass, the greater your BMR. This is very important information if you want to lose weight. The more muscle you have, the more calories you will burn.

Muscle is a metabolically active tissue, and even maintaining a constant mass requires a lot of energy. Obviously, one great way to increase your basal metabolic rate is through bodybuilding, i.e. workouts aimed at growing and strengthening muscle mass.

Harris-Benedict formula (BOO based on total body weight)

The Harris-Benedict equation is a calorie-calculating formula that takes into account height, weight, age, and gender to determine basal metabolic rate (BMR). This makes it more accurate than determining calorie needs based on total weight alone. The only criterion that is not used here is muscle mass. Thus, this equation will be very accurate for everyone except people with excessive muscle mass (calorie needs will be underestimated) and obese people (calorie needs will be overestimated).

Men: BOO = 66 + (13.7 x weight in kg) + (5 x height in cm) - (6.8 x age in years)
Women: BOO = 655 + (9.6 x weight in kg) + (1.8 x height in cm) - (4.7 x age in years)

Example:
You are a woman
You are 30 years old
Your height is 167.6 cm
You weigh 54.5 kg
Your BOO = 655 + 523 + 302 - 141 = 1339 calories per day

Activity coefficients:
Sedentary lifestyle = SBI x 1.2 (little or no exercise, sedentary work)
Light activity = BOO x 1.375 (light physical activity/sports 1-3 times a week)
Moderate activity = BOO x 1.55 (quite a lot of physical activity/sports 3-5 times a week)
High activity = BOO x 1.725 (high physical activity/sports 6-7 times a week)
Very high activity = VOO x 1.9 (very high daily physical activity / sports and physical work or training 2 times a day, for example, marathon, competitions)

Example:
Your BOO 1339 calories per day
You have a moderate level of activity (exercise 3-4 times a week)
Your activity factor is 1.55
Your daily calorie requirement = 1.55 x 1339 = 2075 calories per day

Ketch-McArdle Formula (Lean Body Mass Based BBM)

If you have checked and know exactly what your body's muscle mass is, then you can get the most accurate BOO estimate. The Ketch-McArdle formula takes muscle mass into account and is therefore more accurate than a formula that only takes total body mass into account. The Harris-Benedict equation has separate formulas for men and women because men tend to have more lean body mass (MBM). Since the Ketch-McArdle formula is based on MMT, it applies equally to both men and women.

Basal metabolic rate (men or women) = 370 + (21.6 x lean body mass (MBM) in kg)

Example:
You are a woman
You weigh 54.5 kg
Your total body fat is 20% (10.9 kg fat)
Your body weight minus fat = 43.6 kg
Your BOO = 370 + (21.6 X 43.6) = 1312 calories
To determine your daily calorie requirement (DCA), you simply multiply your DCA by your activity factor:

Example:
Your SBI 1312 calories
You have a moderate level of activity (exercise 3-4 times a week)
Your activity factor is 1.55
Daily calorie requirement = 1.55 X 1312 = 2033 calories

As you may have noticed, the difference between the values ​​​​calculated using the two formulas is small (2075 calories versus 2033 calories), since the person we considered as an example has an average body size and composition. The main advantage of a calculation that takes into account muscle mass is that it more accurately shows the daily calorie requirement (DAR) for very muscular or, conversely, obese people.

Adjust your calorie intake to suit your goal

So, you already know your SPC. The next step is to adjust the number of calories you consume depending on your goal. The math behind calorie balance is very simple. To maintain your weight at the current level, you need to adhere to the SPC. If you want to lose weight, you need to create a calorie deficit in your body, to do this, reduce your BAC (or consume the same amount of calories, but increase physical activity). If your main goal is to gain weight, you need to increase the number of calories you consume. The only thing that differentiates weight loss and weight gain diets is the amount of calories consumed.

Negative calorie balance is the most important factor for weight loss

Counting calories is not only important, it is the most important factor in losing weight. If you consume more calories than you expend, you will not lose weight, no matter what foods you eat. Some foods are stored as fat more easily than others, but always keep in mind that too much of anything, even “healthy foods,” will be stored as fat. You cannot change the laws of thermodynamics and energy balance. In order to burn fat, the body must be in a calorie deficit. This will force your body to use stored fat to fill energy deficits. 0.5 kg of body fat contains 4,500 calories. If you spend a week through diet, exercise, or a combination of both, you will create a deficit in 4500 calories, you will lose 0.5 kg weight. If in a week the deficit is 9000 calories, you will reset 1 kg. A calorie deficit can be created through diet, exercise, or best of all, a combination of both. Since we've already calculated the calorie reduction from exercise (using the activity factor), the deficit we're talking about is exactly what the diet would produce.

Calorie deficit limit: what amount can be considered the maximum permissible?

Everyone knows that if you reduce the number of calories consumed too much, your metabolic rate will slow down, your thyroid gland will reduce its hormone production, and your muscle mass will begin to decrease. How much should you reduce your calories then? There is definitely a limit below which cutting calories can have negative health effects. For weight loss, it is recommended to reduce the number of calories consumed compared to the SPC by at least 500, but no more than 1000. For some people, especially thin people, 1000 calories may be too much of a deficit. The American College of Sports Medicine does not recommend caloric intake below 1,200 per day for women and 1,800 per day for men. But even these quantities are very small. It is best to determine a safe level of calorie deficit based on your weight and DA (daily calorie requirement). Reducing your calorie intake by 15-20% from SPK is a very good start. Sometimes a larger deficit may be needed, but then it is best to increase your exercise while maintaining the same caloric deficit.

Example 1:
Your weight is 54.5 kg
Your SPK is 2033 calories
Calorie deficit for weight loss - 500
Your optimal calorie intake for weight loss: 2033 - 500 = 1533 calories
Example 2:
Your caloric deficit for weight loss is 20% of your BAC (20% of 2033 = 406 calories)
Your optimal calorie intake for weight loss = 1627 calories

A Positive Calorie Balance Is Necessary to Build Muscle

If you want to build muscle and become more muscular, you must consume more calories than you burn in a day. But this is impossible without bodybuilding. Only in this case will the excess calories be used to create new muscle tissue. Once you have determined your BAC, the next step is to increase your calories enough to allow you to gain weight. This is the basic law of energy balance: to build lean body mass, you must eat a diet with a positive balance of calories.

The starting point for weight gain should be an increase in BOP by 300...500 calories per day. Or you can add 15-20% of your SPK.

Example:
Your weight is 54.5 kg
Your SPK is 2033 calories
In order to gain weight, you need 15-20% more calories than your BAC = 305...406 calories
Your optimal calorie intake for weight gain is 2033 + (305...406) = 2338...2439 calories

Change your calorie intake gradually

It is not recommended to make drastic changes to your diet. If, after calculating your daily calorie requirement (DAC) and adjusting it based on your goal, you realize that the required amount of calories is significantly different from your current level of consumption, then you definitely need to change the amount of calories gradually. For example, you have determined that your optimal calorie intake per day should be 1900, but previously your level was only 900 calories per day. If you suddenly increase your calories, your metabolism will slow down. A sudden jump to 1900 calories per day can cause an increase in body fat, because your body is already accustomed to consuming less and a sudden increase in calories will contribute to obesity. The best way is within 3-4 weeks gradually increase the number of calories you consume from 900 to 1900. This will allow your body to adapt and speed up your metabolism.

Measure your results and adjust your calories

The calculations that will help you find the right amount of calories to consume are very simplified and are needed only so that you know where to start. You will need to monitor your progress closely to ensure that this is the right level for you. To make sure you're on the right track, you'll need to monitor your calorie intake, body weight, and body fat percentage. You need to monitor your body weight and body fat percentage to see how your body reacts to dietary changes. If you see that you are not getting the desired results, adjust the number of calories you consume and your activity level. The main thing is not to cut calories too much to lose weight. The best option is to slightly reduce the number of calories and increase daily energy expenditure by increasing the amount, duration and intensity of physical activity.

Good luck on your path to an ideal figure!