Energy exchange of man

"The human body is a" machine "that can release chemical energy associated in the" fuel "of food products; these "fuels" are carbohydrates, fats, proteins and alcohol "(WHO).

The primary use of any of the listed sources has different characteristics in terms of the magnitude of the energy metabolism and the associated metabolic shifts.

Features of various metabolic sources of food energy supply

Indicators	Glucose	Palmitate	Protein
Heat release, kcal:
For 1 mole oxidized	673	2398	475
1 g oxidized	3.74	9.30	5.40
Oxygen consumption:
Mole	66.0	23.0	5.1
L	134	515	114
Carbon dioxide production:
Mole	66.0	16.0	4.1
L	134	358	92
Production of ATP, mol:	36	129	23
Cost of ATP products:
Hell	18.7	18.3	20.7
In / of	3.72	3.99	4.96
C / d	3.72	2.77	4.00
Respiratory rate	1.00	0.70	0.81
Energy equivalent per 1 liter of used oxygen	5.02	4.66	4.17

[1], [2], [3]

Stages of energy exchange

Although the dissimilation and synthesis of the structures of proteins, fats and carbohydrates have characteristic features and specific forms, however, in the transformation of these various substances there are a number of fundamentally common stages and regularities. With respect to the energy released by metabolism, energy metabolism should be divided into three main stages.

At the first stage in the gastrointestinal tract large molecules of nutrients are split into small ones. From carbohydrates are formed 3 hexoses (glucose, galactose, fructose), from proteins - 20 amino acids, from fat (triglycerides) - glycerin and fatty acids, as well as rarer sugars (for example, pentoses, etc.). It is calculated that on average, carbohydrates pass through the human body during its lifetime - 17.5 tons, proteins - 2.5 tons, fats - 1.3 tons. The amount of energy released in phase I is insignificant, while it is released as heat. Thus, during the cleavage of polysaccharides and proteins, about 0.6% is released, fat - 0.14% of the total energy, which is formed when they completely decompose to the final products of metabolism. Therefore, the importance of the chemical reactions of the first phase consists mainly in the preparation of nutrients for the actual release of energy.

At the second stage, these substances undergo further splitting by incomplete combustion. The result of these processes - incomplete combustion - seems unexpected. Of the 25-30 substances, except for CO2 and H2O, only three final products are formed: α-ketoglutaric, oxaloacetic acid and acetic acid in the form of acetylcoenzyme A. Quantitatively, acetylcoenzyme A predominates in this way. In phase II, about 30% of the energy contained in nutrient substances.

At the third stage, the so-called Krebs tricarboxylic acid cycle, the three final products of phase II are burned to carbon dioxide and water. At the same time, 60-70% of the energy of nutrients is released. The Krebs cycle is the common end pathway for the cleavage of both carbohydrates, proteins and fats. This is, as it were, the key point in the exchange, where convergences of various structures converge and the mutual transition of synthetic reactions is possible.

In contrast to stage I - the stages of hydrolysis in the gastrointestinal tract - in the II and III phases of the cleavage of substances, not only the release of energy occurs, but also a special kind of accumulation.

Energy exchange reactions

The conservation of energy is carried out by converting the energy of the splitting of food products into a special form of chemical compounds called macroergas. Carriers of this chemical energy in the body are various phosphorus compounds in which the bond of the phosphoric acid residue is a macroergic bond.

The main place in the energy metabolism belongs to the pyrophosphate bond with the structure of adenosine triphosphate. In the form of this compound in the body, 60 to 70% of all energy released during the breakdown of proteins, fats, carbohydrates is used. The use of energy (oxidation in the form of ATP) is of great biological importance, because due to this mechanism it is possible to separate the place and time of energy release and its actual consumption in the process of organ functioning. It is estimated that in 24 hours the amount of ATP formed and splitting in the body is approximately equal to the mass of the body. The conversion of ATP to ADP releases 41.84-50.2 kJ, or 10-12 kcal.

The energy that is generated as a result of metabolism is expended on the main metabolism, that is, to maintain life in a state of complete rest at an ambient temperature of 20 ° C, growth (plastic metabolism), muscle work and digestion and assimilation of food (specifically dynamic action food). There are differences in the expenditure of energy resulting from the exchange, in an adult and a child.

[4], [5], [6], [7], [8]

BX

The child, like all mammals born immature, has an initial increase in basal metabolism to 1 1/2 years, which then continues to increase steadily in absolute terms and is also regularly reduced per unit body weight.

Often, computational methods for calculating basal metabolism are used. Formulas are usually focused on indicators of either length or body weight.

Calculation of basal metabolism through body weight (kcal / day). FAO / BO3 Recommendations

Age	Boys	Girls
0-2 years	60.9 P-54	61 P - 51
3-9 years	22.7 P + 495	22.5 P + 499
10-17 »	17.5 P +651	12.2 P +746
17-30 »	15.3 P +679	14.7 P + 496

The total energy received from food is distributed to provide basic metabolism, the specific dynamic effect of food, heat losses associated with excretion, physical (motor) activity and growth. In the structure of energy distribution, that is, energy exchange is distinguished:

• Energy received (from food) = Energy deposited + Energy used.
• Energy absorbed = Energy received - Energy excreted.
• Energy metabolized = Energy received - Energy supply (life) and activity, or "basic costs".
• The energy of the basic costs is equal to the sum:
  • basal metabolism;
  • thermoregulation;
  • warming effect of food (SDDP);
  • activity costs;
  • costs for the synthesis of new tissues.
• The energy of deposition is the energy spent on the deposition of protein and fat. Glycogen is not considered, since its deposition (1%) is insignificant.
• Energy of deposition = Energy metabolized - Energy of basic costs.
• Energy cost of growth = Energy of synthesis of new tissues + Energy deposited in new tissue.

The main age differences are the relationship between the costs of growth and, to a lesser extent, the activity.

Age features of the distribution of daily energy expenditure (kcal / kg)

Age	Basic exchange	СДДП	Losses on excretion	Activity	Growth	Total
Premature	60	7th	20	15	50	152
8 weeks	55	7th	Eleven	17th	20	110
10 months	55	7th	Eleven	17th	20	110
4 years	40	6th	8	25	8-10	87-89
14 years	35	6th	6th	20	14	81
Adult	25	6th	6th	10	0	47

As can be seen, the cost of growth is very significant for a small newborn and during the first year of life. Naturally, in an adult they are simply absent. Physical activity creates significant energy expenditure, even in a newborn and an infant, where breast sucking, anxiety, crying and screaming are the expression.

With the child's anxiety, energy consumption increases by 20-60%, and when shouting - in 2-3 times. Diseases make their demands on energy costs. Especially they increase with an increase in body temperature (by 1 ° C increase in the increase in metabolism is 10-16%).

Unlike an adult, children have a lot of energy spent on growth (plastic metabolism). It has now been established that for the accumulation of 1 g of body weight, i.e. A new tissue, it is necessary to spend approximately 29.3 kJ, or 7 kcal. The following estimate is more accurate:

• Energy "cost" of growth = Energy of synthesis + Energy of deposition in new tissue.

In a premature baby, the synthesis energy is 1.3 to 5 kJ (0.3 to 1.2 kcal) per gram, added to the body weight. At term - 1.3 kJ (0.3 kcal) per 1 g of new body weight.

Total energy cost of growth:

• up to 1 year = 21 kJ (5 kcal) per 1 g of new tissue,
• after 1 year = 36.5-50.4 kJ (8.7-12 kcal) per 1 g of new tissue, or about 1% of the total energy of the amount of nutrients.

Since the growth rate in children varies in different periods, the share of plastic metabolism in the total energy expenditure is different. The most intensive growth in the intrauterine period of development, when the mass of the human embryo is increased by 1 billion 20 million times (1.02 × 10 9). The growth rate continues to be quite high in the first months of life. This is evidenced by a significant increase in body weight. Therefore, in children of the first 3 months the share of "plastic" metabolism in energy expenditure is 46%, then in the first year it decreases, but from 4 years, and especially in the prepubertal period, an increase in the intensity of growth is observed, which again reflects in the form of an increase in plastic metabolism. On average, in children 6-12 years of age, 12% of energy needs are spent on growth.

Energy costs for growth

Age	Body weight, kg	Weight gain, g / day	Energy cost, kcal / day	Energy cost, kcal / (kg-day)	As a percentage of basic exchange
1 month	3.9	Thirty	146	37	71
3 »	5.8	28	136	23	41
6 »	8.0	20	126	16	28
1 year	10.4	10	63	6th	Eleven
5 years	17.6	5	32	2	4
14 years old, girls	47.5	18	113	2	8
16 years old, boys	54.0	18	113	2	7th

[9], [10]

Energy consumption for hard-to-account losses

Losses with feces of fat, digestive juices and secretions produced in the wall of the digestive tract and in the glands, with sloughing epithelial cells, with falling off integumentary skin cells, hair, nails, with sweat, and with the attainment of sexual maturity in girls - with menstrual blood. Unfortunately, this issue has not been studied in children. It is believed that in children older than a year it is about 8% of energy costs.

[11]

Energy consumption for activity and maintaining a constant body temperature

The share of energy expenditure on activity and maintenance of body temperature varies with the age of the child (after 5 years this is included in the concept of muscular work). In the first 30 minutes after birth, the temperature of the newborn's body decreases by almost 2 ° C, which causes a significant energy expenditure. In young children, to maintain a constant body temperature at an ambient temperature below the critical temperature (28 ... 32 ° C) and the activity of the child's body is forced to spend 200.8-418.4 kJ / (kg-day), or 48-100 kcal / (kg • day). Therefore, with age, the absolute expenditure of energy on maintaining the constancy of body temperature and activity increases.

However, the proportion of energy consumption for maintaining the constancy of body temperature in children of the first year of life is the lower, the smaller the child. Then again, there is a decrease in energy consumption, since the surface of the body, referred to 1 kg of body weight, again decreases. At the same time, energy consumption for activity (muscular work) increases in children over the age of the year, when the child starts walking, running, exercising, or playing sports.

The energy cost of physical activity

Movement type	Cal / min
Biking at low speed	4,5
Biking at an average speed	7.0
Biking at high speed	11.1
Dancing	3.3-7.7
Football	8.9
Gymnastic exercises on shells	3.5
Running sprint	13.3-16.8
Running for long distances	10.6
Skating	11.5
Cross-country skiing at moderate speed	10.8-15.9
Running on skis at top speed	18.6
Swimming	11.0-14.0

In children aged 6-12 years, the share of energy expended on physical activity is approximately 25% of the energy requirement, and in the adult - 1/3.

[12], [13]

Specific-dynamic action of food

The specific dynamic effect of food varies depending on the nature of the food. Stronger it is expressed with protein-rich foods, less - with the intake of fats and carbohydrates. In children of the second year of life, the specific dynamic effect of food is 7-8%, in children of older age - above 5%.

Expenses for implementation and coping with stress

This is the natural direction of normal life and energy expenditure. The process of life and social adaptation, education and sport, the formation of inter-human relations - all this can be accompanied by stress and additional energy costs. On average, this is an additional 10% of the daily energy "rations". However, in acute and severe diseases or traumas, the level of stress costs can increase very significantly, and this requires consideration in calculating the diet.

Data on the increase in energy requirements for stress are given below.

States	Change in energy demand
Burns depending on the percentage of burned body surface	+ 30 ... 70%
Multiple injuries with hardware ventilation	+ 20 ... 30%
Severe infections and multiple trauma	+ 10 ... 20%
Postoperative period, minor infections, fractures of bones	0 ... + 10%

A persistent energy imbalance (excess or deficiency) causes a change in body weight and body length with all developmental indices and biological age. Even a moderate malnutrition (4-5%) can cause a delay in the child's development. Therefore, food energy security is becoming one of the most important conditions for the adequacy of growth and development. Calculation of this security is necessary to carry out regularly. In most children guidelines for analysis can be recommendations on the total energy of the daily ration, for some children with special health or living conditions, an individual calculation is required for the sum of all energy-consuming components. An example of using common age standards of security and the possibility of some individual correction of these standards can be the following methods for calculating energy costs.

Calculation method for determining basal metabolism

Up to 3 years	3-10 years	10-18 years old
Boys
X = 0.249 kg-0.127	X = 0.095 kg + 2.110	X = 0.074 kg + 2.754
Girls
X = 0.244 kg-0.130	X = 0.085 kg + 2.033	X = 0.056 kg + 2.898

[14], [15],

Additional expenses

Compensation for damage - the main exchange is multiplied: for minor surgery, by 1.2; at a skeletal trauma - on 1,35; at a sepsis - on 1,6; with burns - by 2.1.

Specific-dynamic action of food: + 10% of the basic metabolism.

Physical activity: bed rest + 10% of basic metabolism; sits in the chair + 20% of the basal metabolism; patient's patient's regime + 30% of the basic exchange.

Expenses for a fever: on 1 ° With an average daily rise in temperature of a body + 10-12% from the basic exchange.

Weight gain: up to 1 kg / week + 1260 kJ (300 kcal) per day.

It is customary to formulate certain standards of age-related energy supply for the population. Many countries have such regulations. On their basis, all the food rations of organized collectives are developed. Individual diets are also checked with them.

Recommendations on the energy value of nutrition for young children and up to 11 years

	0-2 months	3-5 months	6-11 months	1-3 years	3-7 years	7-10 years old
Energy, total, kcal	-	-	-	1540	1970	2300
Energy, kcal / kg	115	115	110	-	-	-

Recommendations for energy regulation (kcal / (kg • day))

Age, month	FAO / WHO (1985)	United Nations (1996)
0-1	124	107
1-2	116	109
2-3	109	111
3 ^	103	101
4-10	95-99	100
10-12	100-104	109
12-24	105	90

Calculation and correction of energy exchange are aimed at eliminating the deficiencies of the main energy carriers, i.e., primarily carbohydrates and fats. At the same time, the use of these carriers for specified purposes is possible only when accounting for and correcting the supply of many fundamentally necessary concomitant micronutrients. So, especially important is the appointment of potassium, phosphate, B vitamins, especially thiamine and riboflavin, sometimes carnitine, antioxidants, etc. Failure to comply with this condition can lead to life-incompatible conditions that arise precisely with intensive energy nutrition, especially parenteral.