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Jan 14 2009

Understanding Basal Metabolic Rate

Published by fitblog at 11:09 pm under General Fitness Edit This

 One of the things that you need to become familiar with as you start your journey toward fitness is Basal Metabolic Rate (BMR). What is basal metabolic rate? Well to put it simply, basal metabolic rate (BMR) is the calories that you burn each day by existing.

You should know what you BMR is so that you can be aware of what is an appropriate intake of food and how many extra calories you will need to burn to reach a weight goal or merely to maintain your weight where it is at.  So let’s give a quick overview of BMR.

BMR is different for each individual. Your body burns calories all day long even if you don’t think it is happening after you step on the scale. You burn calories when you body tries to maintain the muscle it has;  you burn calories when your body maintains your body temperature and you burn calories when your body performs basic daily functions such as pumping blood, breathing, etc.

Your basal metabolic rate is determined by many different factors. Here are a few:

Gender - Males have a higher BMR that women (sorry ladies). This is basically because men have a higher percentage of muscle mass and in general they weigh more.

Age - Yes, I am sure that it is no surprise to you that your BMR declines with age (I know that some of us feel as if our BMR has fallen off of a cliff).   All you need to do is look at your belly or thighs to know this is the case.

Weight - The more you weigh the higher your BMR.  In essence, the more weight you are lugging around the more calories you will burn doing it.

Muscle - The more muscle you have the higher your BMR. It takes more calories to maintain a pound of muscle than it does to maintain a pound of fat.

Genetics - Some people are just blessed. I work next to a guy who can’t gain weight if he tries and he is 50. This is not my problem.  Many would love to have this problem. Some have higher metabolisms than others and will burn calories at a faster rate.

Diet - This is one of the biggest mistakes that people make when trying to lose weight. If you starve yourself or otherwise deprive your body of calories you will cause your basal metabolic rate to drop. Sometimes you can cause it to drop by as much as 10% - 20%. Starvation is not a way to lose weight.

Body Temperature - If you have a fever you will burn more calories than you would if you body temperature is normal. This is one of the reasons that you may lose weight when sick (even though you don’t get out of bed).  You may also lose weight due to other reasons as well that are not to comfortable.

Activity Level - The more you exercise the higher your BMR.  Not only do you burn calories from the exercise but you also raise your BMR causing you to burn more calories even while at rest.

How to Calculate Basal Metabolic Rate (BMR)

In order to calculate your BMR you need to figure out how many calories you burn during the day. This would include your maintenance level (calories burned by laying in bed) and your activity level. The more active you are the more you would add to your maintenance level.

The maintenance level for the average woman would be between 1800 and 2100 calories and for the average man it would be between 2500 and 2800. Some individuals due to their activity level require much more. If you remember that during the Olympics a report came out that Michael Phelps needed to consume about 10,000 calories a day just not to lose weight.

Here is a basic equation for calculating your BMR.

Women:
655 + (4.3 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years)

Men:
66 + (6.3 x weight in pounds) + (12.9 x height in inches) - (6.8 x age in years)

I am a 44 year old man who is 5′ 9″ and 180 pounds. So my calculation would be as follows:

66 + (6.3 x 180) + (12.9 x 69) - (6.8 x 44) = 1791

This gets just your resting BMR. Now you have to calculate your activity level. To do this you can use the following rule of thumb.

If you are sedentary : BMR x 20 percent

If you are lightly active: BMR x 30 percent

If you are moderately active (You exercise most days a week.): BMR x 40 percent

If you are very active (You exercise intensely on a daily basis or for prolonged periods.): BMR x 50 percent

I am moderately active so I would take 1791 and multiply it by 1.4 to get my BMR. So each day I burn on average a little more than 2500 calories. If I wanted to lose weight I would have to figure out how to keep my caloric intake underneath of that level.

I hope this was helpful to you. If you don’t want to take the time to calculate your own BMR you can find calculators all over the internet.

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