Your body uses energy constantly and you need energy in everything you do. Exercising consumes a lot of energy in proportion to the time spent on it, especially when performed at high intensity. Your body also needs energy to maintain essential vital functions, such as the functioning of the respiratory and circulatory systems. These vital functions require 60-75% of the daily energy. This energy expenditure is called basal metabolism.
Basal metabolism can be accurately measured in the laboratory, but calculation formulas have been developed for its calculation. Different calculation formulas produce slightly different results and some of them are more suitable for certain target groups.
The most commonly used basal metabolic rate formula is the Harris-Benedict formula. The calculator on this page uses the updated version by Pavlidou published in 2023. The result of Pavlidou's formula is RMR (resting metabolic rate), which indicates the consumption of calories at rest. Earlier Harris-Benedict formulas used the term BMR (basal metabolic rate). BMR is measured in the laboratory right after a night's sleep. RMR testing is not as strict. So, in practice, BMR and RMR are not exactly the same thing. The result of RMR also includes a little bit of energy consumption brought by movement. The measurement results are similar and in the literature these terms are often used in the same sense. When looking at the calculated results of basic metabolism, you should always remember that every person is slightly different and the result is only a calculated estimate.
In addition to basic metabolism, energy is used for food digestion and everyday activity. The share of digestion in the average person's daily energy consumption is about 10%, and the remaining 15–30% of the energy consumption comes from physical activity.
Physical activity refers to all movement created by our muscles. A large part of our physical activity often consists of an activity that we don't often think of as exercise. Such things include, for example, household and yard work, going to the store, transitioning to work or hobby activities. The physical level of work is one big factor in the assessment of activity, because the time it takes is often many times more than leisure time exercise. For example, light standing work can consume up to 140 kcal per hour for a 70-kilogram person, which makes a total of 980 kcal in seven hours. A similar level of energy consumption can be achieved with exercise, for example, running for an hour and a half at 10 km/h.
In the calculation of daily energy consumption, activity is evaluated by using the activity level. The energy required by basal metabolism is multiplied by the activity level. Choosing your own activity level can be difficult. The calculated total energy consumption should only be considered a rough estimate. When looking at energy consumption in the long term, the level falls between 1.1 and 2.5 for the majority of people. A value of 1.1–1.2 is for a person who is completely passive in everyday life. The value of a person who moves a little falls between 1.40 and 1.69. The value of a moderately active and active person is between 1.70 and 1.99. The value of a very active person is between 2.00 and 2.40. Activity above a value of 2.4 occurs for a short time, for example, in elite athletes, but it is difficult to maintain such values for a long time. In this calculator the activity level of an inactive person is set to 1.2.
Lassi Honkanen
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