BMR, or Basal Metabolic Rate, is a measure of the number of calories that your body needs to perform its most basic functions, such as breathing and circulation. BMR does not take into account the calories burned during physical activity or digestion. In other words, it's the number of calories your body would burn if you were to do nothing but rest for 24 hours.
BMR is influenced by several factors, including:
Age: BMR decreases with age.
Sex: Men usually have a higher BMR than women.
Weight: The more you weigh, the higher your BMR, as it takes more energy to maintain a larger body.
Body composition: Muscle burns more calories than fat, so people with a higher muscle mass will have a higher BMR.
Body surface area: BMR increases with body surface area, which is why taller people typically have a higher BMR.
The specific number for a "healthy" BMR can vary greatly depending on these individual factors. However, you can estimate your BMR using various formulas, such as the Harris-Benedict Equation or the Mifflin-St Jeor Equation, which provide a rough calculation based on your age, sex, height, and weight.
Here are the formulas for the Mifflin-St Jeor Equation, which is often considered more accurate:
For men: BMR = 10 * weight(kg) + 6.25 * height(cm) - 5 * age(y) + 5 For women: BMR = 10 * weight(kg) + 6.25 * height(cm) - 5 * age(y) - 161
It's important to remember that these are estimates and individual metabolic rates can vary. For a more accurate measurement, you'd need to undergo specific medical testing.
Once you know your BMR, you can use it to help determine how many calories you need to eat in a day to maintain, lose, or gain weight, taking into account your level of physical activity. This is often referred to as your Total Daily Energy Expenditure (TDEE).
Basal Metabolic Rate (BMR) can be found in various reputable health and fitness resources. Here are some references you can look up for more information:
"Basal Metabolic Rate: Clinical Implications" by Scott Howell (2020) - For a comprehensive, scholarly overview of BMR.
"Energy expenditure in humans: effects of dietary fat and carbohydrate" study published in the American Journal of Physiology (1995) - For the influence of diet on BMR.
"Resting energy expenditure in short-term starvation is increased as a result of an increase in serum norepinephrine" study published in The American Journal of Clinical Nutrition (2000) - Discusses how BMR changes during periods of fasting.
In addition, many websites offer BMR calculators that use the Harris-Benedict Equation or the Mifflin-St Jeor Equation. These calculators, though, should be used as tools for estimation and not as definitive measurements.