1. Body mass index
Body mass index is a calculation that uses your weight and health to estimate how much body fat you have. The calculation for figuring out your BMI is your weight in kilograms divided by your height in metres squared.
The National Institutes of Health (NIH) now defines healthy weight, overweight and obesity according to one's BMI rather than traditional height/weight charts. If your BMI is:
• below 18.5 you're considered underweight
• between 18.5 and 24.9 you're considered a healthy weight
• between 25.0 and 29.9 you're considered overweight
• between 30.0 and 39.9 you're considered obese
• over 40 you may be morbidly obese
While calculating your BMI is a good starting point, it does have inaccuracies as it doesn't take body fat into consideration. For example, body builders tend to have a higher BMI due to their muscle mass, but this doesn't mean they're at risk of being overweight.
2. Body fat percentage and lean body mass
Your body fat percentage is just that – the percentage of your weight which is made up of fat. The part of your body that is not fat is referred to as lean body mass. For example, an individual who weights 160 lb with a lean body mass of 110 has 25 per cent body fat (40 lb of fat). That may sound like a large amount of fat, but keep in mind that a certain amount is necessary to keep healthy. Your body uses fat for natural insulation, energy storage and hormone production.
Page 1 of 2 -- Learn 3 accurate methods for measuring your body fat percentages on page 2.
Body fat becomes a problem when it tips the scales in percentages, usually indicating fatty build up around organs and arteries, putting you at risk for all sorts of health problems.
Body fat percentages can be measured by:
Hydrostatic weighing – This is when you're weighed under water, completely submerged, with all air blown out of your lungs. When done by a trained professional, this method is very accurate.
Skinfold calipers – Also known as a pinch test, this is a simple way to measure body fat, but needs to be done by someone who is highly trained. It is not uncommon to find wide inaccuracies from person to person, depending on the skill of the individual measuring.
Bioelectrical impedance (BIA) – These are scales and hand-held devices that run a low-level (and painless) electrical current through the body. While this measurement can be accurate, it also varies according to the specific device and how it is used. For optimal results, this test should be done in the morning when no alcohol has been consumed for two days prior to the test.
Here's a chart indicating the healthy body fat percentage for someone in your age and gender group:
|20- 40||Under 21||21- 33||33-39||Over 39|
|41- 60||Under 23||23- 35||35- 40||Over 40|
|61- 79||Under 24||24- 36||36- 42||Over 42|
|20- 40||Under 8||8- 19||19- 25||Over 25|
|41- 60||Under 11||11- 22||22- 27||Over 27|
|61- 79||Under 13||13- 25||25- 30||Over 30|
3. Height and weight charts
Height and weight chars, such the Metropolitan Life Chart, were first developed for life insurance companies. Though these charts can offer an ideal body weight for a variety of body frames, there is no modification for age or activity level, making them sometimes inaccurate.
When analyzing your health and weight, use some of the measurements and calculations above to chart where you stand in terms of overall health. If weight loss is your goal, record your starting numbers (BMI, body fat percentage and pounds on the scale) to track your weight loss success. As always, talk to your doctor if you have any questions or concerns.
Page 2 of 2 – Have you always wondered how to properly figure out your BMI? Dr. Joey Shulman shares the simple calculation she uses on page 1.