Yesterday I wrote about how your Body Fat Percentage (BFP) is a more accurate way to measure excess body fat when compared to your BMI. The New York Times reported recently that some studies suggest that BFP is a better indicator of health than your weight.
Underwater weighing is considered the most accurate method for determining your BFP, the more body fat you have the less you weigh in water. This method costs about $200 a pop. So it is not surprising that sales of scales with built-in body-fat monitors using bioelectrical impedance are up. They work by measuring how fast an electrical signal travels through your body. The more muscle you have the faster the signal travels. Fat contains almost no water, while muscles are about 70% water and water conducts electricity that is why the signal moves more quickly through muscle. If you are dehydrated you will read as having a higher percentage of fat (another reason to stay hydrated).
These types of scales were first introduced in the early 90s but the technology has improved and the scales are less expensive now. There are many out there on the market ranging in price, starting with the Health O Meter BFM-687 (I just love the name of this scale - it sounds so very 1950s sci-fi) for $34.98 found at Sam’s Club stores. Going more upscale if you will, there is the Tanita Innerscan BC551 for $139.99 available online at the competitive edge.
NY Times gave both scales good reviews, when tested for accuracy they both measured within a variable range of 4 percentage points of accuracy.