Basal Metabolism

What is it?

Basal Metabolism is the energy your body needs to do things like breathing, keep your heart beating, filtering blood, making blood cells, maintaining body temperature and acid-base balance, and all of the other processes that go on, even when you are sleeping.

It does not include the energy needed for digestion, physical activity or emotional reactions.

It is estimated that 50-60% of the calories you use each day are to support your basal metabolism.

BMR or Basal Metabolic Rate

BMR stands for Basal Metabolic Rate and is a number value given to the rate of calorie usage while you are in a comfortable setting, after a restful sleep, a 12-hour fast, and with no physical exertion or emotional upheaval.

It is generally shown in kilocalories per kilogram of body weight per hour.

Factors affecting Basal Metabolism and Basal Metabolic Rate

The BMR is different for each person and changes as various factors change. The rate that you use calories for basic body processes can be affected by an umber of things: 


--Amount of muscle

--The temperature in the room




Naturally, calorie needs go up as soon as you start moving around, or if you are upset or stimulated in some way. Even the process of digesting food will raise your metabolic rate. If you do vigorous activity, your calorie usage rate will increase even more, at least for a period of time.

The value of knowing your Basal Metabolic Rate is that it can help you determine how many calories you need to maintain weight or, if necessary, to lose weight.

What about Body Mass Index (BMI)?

Whenever weight loss and obesity are discussed, health experts always get around to talking about our Body Mass Index (BMI). This refers to a calculation that is used by health care providers to determine if a person is a reasonable weight for his or her height.

Body Mass Index Calculator

What the numbers mean

It is generally considered healthy to have a BMI between 18.5 and 24.9. If your BMI is below 18.5, you would be considered underweight and if your BMI is above 25 you are considered overweight. A BMI of 30 and above is considered obese, and a BMI above 40, morbidly obese.

What’s missing from the Basal Metabolism equation?

While this system of determining BMI may be useful in a general sense, it does not take into account body composition, which is the proportion of fat, muscle, bone and other tissue in your body. Since muscle weighs more than fat, if you are an athlete with a lot of muscle and very little fat, your BMI may fall in the “obese” range, even though you are in great shape and not over fat at all.

In addition, this system does not allow for differences in bone size or density, which can factor into the issue of whether you are overweight for your height. (You always knew you had heavy bones!)

These differences in body composition explain why two people who are the same height and weight may look completely different. If one person has a lower body fat percentage, he or she will look slimmer than a person of the same height and weight with a higher percentage of fat.

The value of calculating your number

Having said that, there may be some real value in taking a moment to calculate your BMI number, especially if you are not an athlete, since it can be a piece in the puzzle of your overall health picture. When you add in your other “numbers” such as blood pressure, blood sugar, triglycerides and cholesterol, along with what you know about your lifestyle, you will get a sum total of your prospect for health and longevity.

Click here to go from Basal Metabolism page to What is Metabolic Syndrome page.