BMR, BMI and Percent Body Fat

calculator     Update on my weight loss journey:  My goal is to lose 80 pounds and then reevaluate.  So far I have lost 20.2 pounds!  Yay!  60 to go!  BMI is 33.9.

So, maintaining a healthy weight is about more than just what the scale says.  It’s about body composition.  And it’s something you need to understand.

Basal Metabolic Rate (BMR)

BMR measures the energy used by your body to keep normal body functions when your body is at rest.  For example, digestion uses a lot of energy.  BMR tells you how many calories you need to keep the status quo.  Activity level affects this number.  Bottom line, if you take in more calories than you use through metabolism and activity, you will gain weight.  It’s not rocket science, it’s just common sense.

Body Mass = Fat Mass + Fat Free Mass.

The body is broken into 2 parts.  Put simply,

*Fat Mass = Fat component.  It’s made up of essential fat and storage fat.  Essential fat is the fat your tissues and organs need to function and survive (yes we need fat to live).  Storage fat is the excess fat we store in adipose (fat) tissue (this is what we don’t want lots of).  This includes internal storage fat (fat around internal organs) and subcutaneous storage fat (that jiggly stuff below the skin).  This body fat is the most variable component of our body’s composition.  This is the stuff we want to get rid of when dieting and improving health.

*Fat Free Mass = Fat-free component.  It’s made up of water, organs, bones, muscles, ligaments, etc. and is all the non-fat, essential parts of us.

*Lean Body Mass is slightly different.  It includes the essential fats used within your body tissues.

Body Mass Index (BMI)

The formula used to calculate BMI is kg/m².  This is weight in kilograms divided by height in meters squared.  There are many websites available where you can enter your height and weight and it will do the math for you.  The standard BMI ranges are as follows:

Underweight = BMI below 18.6

Healthy Range = BMI 18.6 to 24.9

Overweight = BMI 25.0 to 29.9

Obesity = BMI 30.0 to 39.9

Extreme Obesity = BMI over 40.0

Percent Body Fat

This is the percent of the body that is fat.  Remember fat is essential to life, so you don’t want this number too low or you will have health issues.  But you don’t want it too high either.  Realize women need more fat than men do for various reasons.  The following shows generally accepted ranges.

Essential fat requirements                                                       8% women     5% men

Minimum body fat requirements (DO NOT go below this)     15% women     5% men

Optimal fitness range                                                        16-25% women     12-18% men

Healthy body fat percentage ranges                                 18-30% women     10-25% men

Overweight/obesity (unnecessary, jiggly stuff)               over 30% women     over 25% men

How do I calculate my numbers?

Many books and websites can help you with calculations.  You can go to your local gym and have them calculate it for you.  Some health centers can also help you out.

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