Energy Efficiency Of The Body

The basis of energy efficiency is to achieve a balance between caloric intake and energy expenditure.

Daily energy costs include three main components. The sum of them determines the total individual losses of the body within 24 hours.

The most significant share of total energy expenditure is allocated to the energy expended to maintain basal metabolism . For this purpose, a special basal metabolic rate -  BMR (Basal Metabolic Rate) was introduced .

The latter is a measure of the energy needed to carry out basic life processes such as the functioning of organs and the course of biochemical reactions.

Basal metabolism depends on the following factors:

1) Gender . Men have more intense BMR.

2) Age . BMR shows higher values ​​in adolescence and childhood.

3) Medium temperature. Warmer weather slows down the basal metabolism.

4) Body temperature. In a febrile condition, the intensity of metabolism is higher, respectively the value of BMR also increases.

There are two ways to calculate basal metabolism.

One is to indirectly judge it by the measured oxygen consumption at rest, soon after waking up and without eating for at least the previous 12 hours.

The second way to determine BMR is to use formulas tailored to age, gender and body weight. The table below is among the most commonly used.

The unit of measurement for basal metabolism is kcal / 24 hours.

Therefore, for a 24-year-old man weighing 70 kg, the BMR value is calculated as follows:

BMR = 15.06 x 70 + 692 = 1054.2 + 692 = 1746.2 kcal / 24 hours.

The above table does not include all factors influencing BMR. There are also more complex formulas that reflect specific natural or pathological conditions. The calculated method of calculation is approximate to the absolutely real value and gives an approximate idea of ​​BMR.

The second component in daily energy expenditure is the energy that provides physical activity . In the world literature there are three types of physical activity - light, moderate and high . The energy for each of them is calculated as a percentage of BMR.

If we use the same example for a 24-year-old, 70 kg man who works all day in the office in front of the computer, then his physical activity will be defined as low and the energy for physical work will be calculated as follows:

Energy for physical work = 30% of 1746.2 = 0.3x1746.2 = 523.86 kcal / 24 hours.

The third main component in daily energy expenditure is the energy needed for digestion . It is 10% of BMR. This is the energy that the gastrointestinal tract invests to ensure peristalsis and secretion of enzymes, mucus and other substances.

If we use the same example, we get the following result:

Digestive energy = 10% of 1746.2 = 0.1x1746.2 = 174.62 kcal / 24 hours.

The total energy consumed during the day is the sum of the three considered. For the example considered, it looks like this:

Total energy for 24 hours = BMR + Energy for physical activity. + Digestive energy

Total energy for 24 hours = 1746.2 + 523.86 + 174.62 = 2444.68 kcal / 24 hours.

In order to be energy efficient , this man must eat a total of daily food, the energy value of which corresponds to the calculated daily energy expenditure.

If the total daily intake exceeds the total energy expenditure, the difference is stored in the body in the form of fat. It was found that 1 kilogram of accumulated fat corresponds to 7,700 excess calories, ie. these are calories consumed above the level of individual energy expenditure.