Tag Archives: Underweight

Body Fat Percentage (BFP) or Body Mass Index (BMI) ?

Those digits can deceive, making you feel pudgy when you’re not or giving you false slim-security. Use BMI or body-fat percentage (BFP) to suss out your true fatness. We’ve got the skinny on the way that’s right for you.

Reality check: Body-fat percentage

Who it’s for:  Athletes or fitness fanatics who might be dubbed overweight by BMI because their muscle mass makes them naturally heavier. BFP is also a wake-up call for “skinny fat” women, whose BMI is fine but who, because their muscle tone is zilch, could have dangerously high body fat, which can increase the risk for diabetes, heart disease and other serious ailments. (Not either? Anyone can use it to gauge her body fat.)

How it works: The easiest way to get an accurate BFP reading is a skin-fold test. Calipers (they look like long prongs) measure thickness near your hip and at your thigh and triceps.

Where to get it: Many gyms offer the test gratis to members, or you can ask your doc to test you.

What your number means:

  • 14-20% Oh, yeah! You’re athlete-level fit.
  • 21-24% Sweet. You’re in great shape.
  • 25-31% OK, but your health risks may rise; up your strength training.
  • 32+% You’re actually obese (even though you may not look it).


Reality check: Body-mass index

Who it’s for:  Workout novices who need to lose a lot of weight in order to get fit, says Pete McCall, an exercise physiologist with the American Council on Exercise. As you shed major pounds, you’ll see your BMI go down–an encouraging sign that you’re on track. BMI also helps average-weight, average-muscle-tone folks get a snapshot of their health. (To know your actual body fat, you need to use BFP.) But if you’re just looking to drop a size, skip this calculator. Replacing a few pounds of fat with muscle won’t always change BMI, and you may think you’re not progressing when you are, McCall notes.

How it works: The formula takes how tall you are and how many pounds you carry, then estimates if you’re at a healthy weight.

What your number means:

  • 18.4 or less Underweight. You actually need a little fat to be healthy.
  • 18.5-24.9 Normal weight. You’re in the zone.
  • 25.0-29.9 Overweight. Health risks rise in this range.
  • 30+ Obese. Time for a major body transformation!






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Picture of an Obese Teenager (146kg/322lb) wit...

Image via Wikipedia

Body Mass Index is an indirect measure of body fat based on weight and height.

Formula: weight (lb) / [height (in)]2x 703

Calculate BMI by dividing weight in pounds (lbs) by height in inches (in) squared and multiplying by a conversion factor of 703.

Example: Weight = 150 lbs, Height = 5’5″ (65″)
Calculation: [150 ÷ (65)2] x 703 = 24.96


Weight Status
Below 18.5 Underweight
18.5 – 24.9 Normal
25.0 – 29.9 Overweight
30.0 and Above Obese

According to the BMI weight status categories, anyone with a BMI over 25 would be classified as overweight and anyone with a BMI over 30 would be classified as obese.

It is important to remember, however, that BMI is not a direct measure of body fatness and that BMI is calculated from an individual’s weight which includes both muscle and fat. As a result, some individuals may have a high BMI but not have a high percentage of body fat. For example, highly trained athletes may have a high BMI because of increased muscularity rather than increased body fatness. Although some people with a BMI in the overweight range (from 25.0 to 29.9) may not have excess body fatness, most people with a BMI in the obese range (equal to or greater than 30) will have increased levels of body fatness.

It is also important to remember that weight is only one factor related to risk for disease. If you have questions or concerns about the appropriateness of your weight, you should discuss them with your healthcare provider.


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