A person's basal metabolic rate, or BMR, is the minimum number of calories needed daily in order to stay alive. This is basically the fewest number of calories you need to be in a state of rest the entire day. The body burns calories while performing everyday processes such as pumping blood, breathing and maintaining body temperature. Depending on many factors, BMR can burn up to 70 percent of the daily calories expended. If you are looking to lose, gain or maintain your current weight, it is important to know your BMR.
The easiest way to calculate your BMR is by using the free BMR Calculator
So what is BMR? Each person's BMR is different. It is affected by many factors, including:
Gender: Men tend to have a higher BMR because they have a lower percentage of body fat and more muscle mass.
Age: BMR decreases with age. After 20 years of age, you can expect your BMR to decrease 2 percent per decade.
Genetics: Some people are born with slow metabolisms, while others can be very fast.
Weight: BMR increases with weight. An obese woman has a 25 percent BMR than a thin woman.
Diet: Starving yourself and going on a restrictive low-calorie diet can reduce your BMR by up to 20 percent.
Exercise: Regular exercise not only burns calories, but also increases lean muscle mass, which increases your BMR. This means you burn more calories while at rest.
Body Temperature: A hotter internal body temperature results in an increased BMR. For every one-degree increase in temperature, your BMR rises by 7 percent.
Body Fat Percentage: A lower body fat percentage equates to a higher BMR. This is typically why men have a BMR that is 10-15 percent faster than women.
Body Surface Area: This is a measurement of your weight and height. Those with a higher body surface area have a higher BMR. This means that tall, thin people have a higher BMR than short, overweight people.
External Temperature: Cold temperatures can raise your BMR, since your body need to burn additional calories in order to stay warm. Hot temperatures do not typically have any affect, although prolonged exposure to heat can possibly increase your BMR.
Glands: Thyroxin, which is produced in your thyroid, regulates BMR. BMR increases with thyroxin output.
There are also some short-term factors that can affect your BMR, such as illness, fever, stress and extreme dieting.
There is a quick and easy way to determine your caloric needs by using your body weight. To maintain your current weight, you need to consume 15-16 calories daily per pound of body weight. To lose weight, you would need to consume 12-13 calories per pound of body weight. To gain weight, you would need to consume 18-19 calories per pound of body weight.
These are just estimates to give you a starting point for determining what is BMR. You should monitor your diet closely to see what works for you.