The basal metabolic rate of humans is the energy they need within 24 hours for self-preservation in complete calm, sober (12 hours after the last food intake) and at indifferent temperature. The indifference temperature is the temperature of the ambient air at which no additional power needs to be expended for maintaining the body core temperature of just below 37 degrees Celsius for heat generation or cooling (sweating). It is about 28 degrees Celsius for humans.
Any energy consumption in excess of the basal metabolic rate is referred to as power turnover. Basic sales plus sales make up the total sales.
The basal metabolic rate is dependent on the body mass of some other factors, such as the percentage of muscle and fat mass, height and hormone status. The basal metabolic rate of men per kg of body mass is on average about 10% higher than that of women, which is mainly due to the hormone status and to a different distribution of fat in the body. Of course, this can vary greatly from person to person.
In a rough approximation, the basal metabolic rate of an adult, normal-weight woman is approximately 22 kcal or 90 kJ per kg of body mass. In an adult, normal-weight man, the basal metabolic rate is about 24 kcal or 100 kJ per kg of body mass.
The level of basal metabolic rate plus demand for the power turnover is crucial for the total calorie requirement. A diet whose utilizable energy sustainably and significantly exceeds the need for basic and performance gains gives the body the opportunity to apply the excess energy in the form of fat reserves for periods of scarce food supply. In the reverse case of a scarce supply of food, which leads to a significantly negative total sales balance, the person has a so-called hunger metabolism, to which the body switches if it has to endure a negative energy balance of more than 500 kcal per day for at least three days.
The basal metabolic rate can be reduced by up to 50% in the emergency program. The austerity program is genetically programmed and makes it possible to survive times with very scarce food supply better and longer. Therefore, with limited calorie intake to maintain a diet, it may be of interest to consider the level of basal metabolic rate in the overall energy balance to keep the body from falling into the austerity program.
The basal metabolic rate in absolute resting phase, the skeletal muscle and the liver with 26% each have the largest share. The brain consumes about 18%, the heart 9% and the kidneys 7% despite the resting phase with pause for thought. The remaining share of about 14% is accounted for by the other bodies.
A direct measurement of the basal metabolic rate is relatively difficult and expensive, so that is normally waived. As an alternative to the direct measurement, several calculation formulas are available that use easily measurable parameters for the approximate determination of the basal metabolic rate. One of the modern formulas proposed by Mifflin and St. Jeor in the United States in 1990 takes into account not only different absolute constants for gender, but also the size and age of the person. The modern calculation formula for the basal metabolic rate also takes into account the changed way of life and diet in the last 100 years. Another formula takes into account that the basal metabolic rate decreases with higher fat content per kg of body mass. The fat content is taken into account via the body mass index (BMI).
Problems related to the basal metabolic rate are usually caused by a comparatively low basal metabolic rate. In most cases, a decreased basal metabolic rate leads to obesity, as with unchanged dietary habits, a larger portion of the energy supply in the diet is available for storage in the form of fat.
The level of basal metabolic rate is partly genetic and can only be partially influenced by the type of food. However, the metabolism can be clearly stimulated by hot spices such as chilli, curry or cayenne pepper, which all contain the substance capsaicin. Thus, the basal metabolic rate of capsaicin can be increased by up to 25%.
The most common problems with low metabolic rate are associated with hypothyroidism. Other diseases that affect the endocrine system may also affect the basal metabolism, leading to weight gain.
Many women have problems with unwanted weight gain after menopause. The altered hormone situation leads to a reduced basal metabolic rate, so that a weight gain is favored.
Stress hormones tend to stimulate the metabolism and increase the basal metabolic rate, while depression has a depressing effect on the basal metabolic rate. Even medications such as antidepressants, which have a dampening effect on the metabolism, often lead to unwanted weight gain due to the reduction of the basal metabolic rate and increased appetite.
The greatest influence on a drastic reduction in the basal metabolic rate, however, is the healthy body itself, when it puts the metabolism in the energy-saving mode. The basal metabolic rate can be reduced by up to 50% in this case.