Determining your body fat percentage is useful for weight management, bodybuilding, sports training, and health risk assessment. You can find out:
- Approximately how much body fat you have
- If you have too much body fat
- How your body fat may affect your health risk
How to Use Body Fat Knowledge
It's worth knowing that all body fat measurement methods have limitations. Some tools, like body calipers, may not sufficiently evaluate the fat that is stored around internal organs (visceral fat). This type of fat increases risk for heart disease and diabetes more than fat stored in tissue just under the skin. Further, individuals who are on the overfat side but who exercise consistently may be fitter and perhaps healthier than, for example, a skinny smoker who does not exercise.
Although you should feel free to monitor your body fat for fitness and weight management purposes, your doctor (perhaps with the assistance of a nutrition professional) is the best person to make health risk assessments. He or she will take all of your disease risk factors into account, such as blood cholesterol, glucose measurements, body fat, and fitness level.
Body Fat Charts
Defining absolute “healthy” body fat levels is less desirable than setting ranges of acceptable fat percentages. Women naturally carry more body fat than men, and a healthy range could be from 18 to 25 percent for relatively inactive women and 12 to 20 percent for athletes and fitness enthusiasts, although the distinction is contrived. For men, 12 to 18 percent for non-athletes and 5 to 12 percent for fitness enthusiasts are the normal ranges, even though some charts have higher maximums. For men and women over age 40, the percentages are usually adjusted upward, although this needs reviewing in my view.
Frankly, many of the professional body fat charts project an unfortunate spin on body fatness even though they are only meant as a guide. Some use categories like “underfat," “healthy,” "lean,” or "ideal.” In my opinion, that suggests that being in the "underfat" or "lean" sectors is unhealthy. This is just untrue for many fit people. I don’t accept that a 20 year-old woman with 15 percent body fat who runs more than six miles in 50 minutes and deadlifts 100 pounds should be categorized as underfat and by inference, unhealthy. The notation in these charts is plainly unhelpful and needs updating that's in line with current community standards of health and fitness.
One point to note is that women who get down to around 12 percent body fat experience hormonal disturbances that may result in loss of periods, bone loss, and disordered eating. This is called the “female athlete triad” in sports medicine. Endurance athletes and some women strength trainers may compete effectively at this body fat level, so this is not necessarily unhealthy. But it does require the management and advice of a sports medicine professional.
Body Mass Index or BMI
The body mass index is a body weight and height formula designed to provide a snapshot of your body fatness. It is calculated by dividing your weight in kilograms by your height in meters, squared. The easiest way to calculate this is to use an online calculator like this one from the US Heart Blood and Lung Institute. It allows you to calculate your BMI using pounds, feet, and inches as well as in kilograms and meters.
The BMI categories of are as follows:
- Normal weight = 18.5 to 24.9
- Overweight = 25 to 29.9
- Obese = 30 or greater
The BMI gets consistently criticized by exercise professionals because, like the charts above, athletes or other heavily muscled people are not factored in. That tends to skew the results by placing bodybuilders and heavily built people in the overweight category.
In a sense, this criticism is unjustified because the BMI is only one tool in the hands of experienced health professionals. A keen eye plus a waist measurement is often all that is required to establish if someone is overweight.
Waist measurements have evolved to be a useful risk assessment tool for both men and women. Naturally, a thin waist does not a healthy person make--you could be malnourished or ill from any number of chronic diseases. Yet waist measurements--being a measure of body fatness--can be indicative of one's risk of chronic diseases such as heart disease, metabolic syndrome, and type 2 diabetes.
Healthy waist measurements Here are the healthy waist sizes for men and women based on the International Diabetes Federation consensus worldwide definition of metabolic syndrome:
- Caucasian men: 37 inches (94 centimeters)
- Caucasian women: 31.5 inches (80 centimeters)
Values for other groups may be different; Asians' may be lower while those for Pacific Islanders may be higher.
That sounds slim, doesn’t it? And it is, but don’t panic. The best way to apply this is to consider that your risk of metabolic syndrome, and subsequently heart disease and diabetes, will start to rise as you exceed these baselines. And your other disease risk factors play into this, as well.