Calculate your Body Fat
WHAT IS BODY FAT PERCENTAGE?
Our bodies are made up of a lot of different kinds of tissues (plus a lot of water). There is muscle, fat, bone, and specialized tissue such as is in our various organs. The body fat percentage is just that – the percentage of our weight which is made up of fat. Body fat percentage is similar to terms such as body fat ratio and body composition. The part that isn't fat is called our “lean body mass”. A 160 lb person with a lean body mass of 120 lbs has 25% body fat (40 lbs of fat). That may sound like a lot, but our bodies need a certain amount of fat - for insulation, energy storage, hormone production, and other functions scientists are just discovering.
CALCULATING YOUR BODY FAT PERCENTAGE
The following body fat calculator uses the U.S. Navy Circumference Method where three or four body measurements are fed into a fixed formula to estimate the percentage of your body that is made up of fat. The measurements need to be accurate to within 0.5cm or 0.25 inches and should be taken as follows:
- Height: taken without shoes
- Neck: taken below the larynx sloping slightly downward at the front
- Waist: for men at navel height, for women at the smallest point
- Hips: (female only) at the largest point
Age-Adusted Body Fat Percentage Recommendations
|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%|
|Age (Yrs.)||Underfat||Healthy Range||Overweight||Obese|
|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%|
These charts are based on World Health Organization and National Institutes of Health recommendations, and takes age into account.
Please do not confuse these numbers with the BMI (Body Mass Index) scores, which are not the same thing.Source: Gallagher et al. Am J Clin Nut 2000; 72:694-701
HOW MUCH BODY FAT SHOULD A PERSON HAVE?
This depends upon a few variables. Women need more body fat than men. Breasts are almost all fat, and women have more fat around their hips – that’s just the way it was meant to be! If a woman’s body fat drops too low, she will stop menstruating. Also, men naturally have a greater amount of muscle bulk. Another factor is age - as people get older, their muscles tend to shrink, and they tend to accumulate visceral fat. This is at least partially related to the decline in testosterone and other hormones. You can find your individual body fat recommendation in these charts. It is important not to confuse BMI with body fat. The BMI (body mass index) numbers are NOT percentages of body fat. I often see advice on Web sites where the two are plainly being confused. For example, a BMI of 29 is in the overweight range for women – this has nothing to do with 29% body fat, which is considered healthy.
WHAT’S THE DIFFERENCE BETWEEN BODY FAT PERCENTAGE AND BMI?
BMI (body mass index) is a formula based on height and weight. It was developed because in the general population, it is correlated with body fat. However, there are quite a few groups of people for whom BMI is not as accurate – short women and muscular people, to name two. BMI also varies according to some ethnic groups. Also, for people who are interested in changing their body composition and not just their weight, knowing body fat percentage is an improvement over BMI. For example, if you are exercising to build muscle (a good goal), knowing your body fat percentage is a good idea. Also, when losing weight, you want to preserve as much lean body mass as possible. (Low carb diets generally produce better results than high carb ones for this purpose.)