Your Body Mass Index (BMI) is a measurement of your body fat percentage. And based on the results, you are labeled normal, overweight or obese.
But BMI can give you some crazy results. Using this measurement, I’m considered obese.
And so is NFL superstar Tom Brady.
You see, BMI only compares your height against your weight. It doesn’t distinguish between fat and muscle. But here’s the thing… Muscle is much denser than fat. So if you have a lot of muscle, you can have a high BMI but still be lean. There’s a much more reliable test to measure your body’s composition of fat and muscle. It’s called dual-energy X-ray absorptiometry (DXA or DEXA).
In my clinic, it’s one of the first tests I give to my patients.
You probably know the DEXA test as the gold standard for measuring bone density. But new research shows it can also give you a detailed snapshot of your body’s composition of bone, muscle and fat.
In a recent study of 50 women, doctors compared BMI with DEXA results. They found that some women who were told they were overweight based on their BMI actually had normal fat levels on their DEXA.1
And 18.5% of the women with normal BMI actually had a lot of excess fat based on their DEXA. In other words, they were “skinny fat” people.
You see, the BMI also can’t measure deadly visceral fat. This type of fat collects in your abdominal cavity. It surrounds your organs and restricts them. Visceral fat is also a haven for toxins that can’t be cleaned by the liver. They contribute to heart disease, diabetes and cancer.2
I advise all my patients to stop obsessing over the scale and start monitoring their body composition.
DEXA scans are the best way to do that. The scan takes just a few minutes. Afterward you receive a report detailing the mass of your bones, fat, muscle and organs broken out individually. It’s great for tracking your progress in building muscle and losing fat from your diet and workouts. You do get a small amount of radiation from the scan. But it’s less than 10 microsieverts or just a fraction of a chest x-ray or mammogram.
I measure all my patients’ body composition with a DEXA scan at my Sears Institute for Anti-Aging Medicine. This amazing scan is fast and relatively painless. If you’re interested in having one done, please call 561-784-7852. My staff will be happy to answer all your questions.
But if you can’t get a DEXA scan, there are still other ways to measure your own body composition that are more reliable than the BMI.
5 Body Fat Tests Better Than BMI
Here are five ways to get a handle on your body fat percentage.
1. Technology. There are now bathroom scales and hand-held devices to calculate your body fat. They send a safe and very low electrical current through the lower half of your body. The current flows more quickly through water and muscle than bone or fat. They calculate your body fat based on the speed of the current. Don’t use these if you are pregnant or have a heart pacemaker or defibrillator.
2. Calipers. This method is not as accurate as a DEXA. A recent study found that calipers can underestimate body fat by 3–5.6% compared to the DEXA.3 But it’s fast, inexpensive and easy.
They come with simple instruction manuals that will show you how to get a good read on how much fat you’re carrying. It’s best to measure at three different body sites. Then average the measurements to get an accurate body fat percentage. Most men carry between 15-17% body fat. For women, the average is between 18-22%.
3. Skin Pinch. Another easy way is to grab your skin between your finger and thumb just to the side of your navel and measure the thickness of the skin fold. It should measure less than 1 inch in both men and women. Even this rough test of your body fat is more useful than the archaic and misleading weight tables invented by insurance companies.
4. Waist/Hip Ratio. Another simple method is to measure your waist and hip girths. Simply wrap a tape measure around your waist at your navel and record the number in inches. Next measure the circumference around your hips at their widest point. Waist girth should be less than your hip girth for both men and women. Ideally, for men is a waist girth that’s one or more inches less than their hips. For women, a waist three or more inches less than their hips.
5. Waist Measure. A waist circumference test is a simple way to see if you’re at risk for visceral fat. Just wrap a flexible measuring tape around the smallest part of your waist. By knowing where you stand and taking action, you’re helping prevent deadly sickness and disease.
To Your Good Health,
Al Sears, MD, CNS
1. Goldstein, S., et al. “Is a percentile of body fat determined by DXA a better surrogate for metabolic health than BMI?” North American Menopause Society. December 2014.
2. Slentz, C., , et al. “Inactivity, exercise and visceral fat. STRRIDE: A randomized, controlled study of exercise intensity and amount;” J Appl Physiol., 99. July 7, 2005.
3. Ball S, Swan PD, DeSimone R. “Comparison of anthropometry to dual energy X-ray absorptiometry: a new prediction equation for women.” Res Q Exerc Sport. 2004 Sep.