The energy requirement or calorie requirement is composed of the basal metabolic rate and the power metabolic rate and varies from person to person. We have an increased energy requirement in the case of stress, fever and hyperthyroidism, in addition, women during pregnancy and lactation – in old age and mental disorders, on the other hand, the requirement is lowered. Climatic influences also play a role. For example, the calorie requirement is also increased in extreme cold or heat.
Basal metabolic rate
The basal metabolic rate is the daily amount of energy needed to maintain all bodily functions (breathing, heartbeat, muscle activity, etc.) at rest over a 24-hour period. It is about 60 to 70 % of the total calorie requirement. During sleep, it drops by 10%.
The basal metabolic rate depends on age, height, gender and weight. The higher the body weight, the higher the basal metabolic rate. However, fatty tissue consumes much less energy than muscles, for example. Those who exercise therefore have an advantage, because the greater the proportion of muscle mass, the higher the basal metabolic rate.
To calculate the basal metabolic rate – since the exact determination of fat and muscle mass is difficult – the body weight is usually used.
Power turnover
The power metabolic rate is essentially determined by physical activity at work and during leisure time. Caloric expenditure from physical activity accounts for about 20% to 30% of total caloric expenditure.
Today, the power metabolism is often determined with the help of the so-called PAL values – Physical Activity Level. The PAL depends on the type and duration of occupational or sporting activities:
| Activity | Examples | PAL |
|---|---|---|
| Very low | Exclusively sitting or lying down, such as in illness or old age. | 1,2 |
| Light | Exclusively sedentary with less or no physical exertion, for example, VDU work, without exercise. | 1,4–1,5 |
| Normal | Sedentary work, intermediate walking or standing, for example, motorist. | 1,6–1,7 |
| Medium heavy | Predominantly walking and standing occupations, for example, sales clerk, waiter, handyman, homemaker. | 1,8–1,9 |
| Heavy | Physically demanding jobs, for example, construction workers, competitive athletes, farmers. | 2,0–2,4 |
To maintain body weight, food must be supplied with the individually required amount of energy. If this value is exceeded in the long term, one can expect that the body will accumulate the excess energy in the form of fat deposits.
Calculation of the energy requirement
To calculate your calorie requirements, there is an interactive energy requirement calculator from the University of Hohenheim.
