How to Use a Body Composition Scale

Setting a New Year’s Resolution to lose weight? Read this before you buy a trendy new body composition scale.

Fitbit Aria 2 body composition scale

Photo courtesy of Fitbit

Photo courtesy of Fitbit

Right about now there’s a good chance you’re renewing your gym membership, relishing in new athleisure wear gifts or conjuring up a healthy plan you’re definitely going to stick to this year. Part of that plan may even include a fancy body composition scale. Lucky for us, they’re more affordable than ever and garnering an increasing number of bells and whistles as companies release updated options (like the and ). These models sync seamlessly to smartphone apps (which show bright and beautiful charts of your progress) and provide extra data that might motivate you.

Special measures

“A normal scale tells a person’s overall weight, but not how much fat someone has,” says Rekha Kumar, MD, MS, an endocrinologist and obesity specialist at New York Presbyterian Hospital/Weill-Cornell Medical College. “Now that we understand the health risks of having too much body fat, people want this information.” She says historically, accurate body fat measures have come from things like , the and the , but they’re expensive or not readily available.

Enter the at-home body composition scale, which uses to figure out how much fat we have. When you stand on them barefoot, they send a little electrical current up one leg and down the other. Fat doesn’t conduct electricity very well, so the more fat a person has, the slower the current will be. “The upside is there’s something people can easily buy now to get that measurement,” says Kumar, “but the downside is these scales are not very accurate because the method they use can be affected by how much water you drink, when you last ate or exercised and even the dirt on your feet.”

On the right track

However, she insists they can be useful for tracking purposes. If you stick to a regular exercise schedule, drink the same amount of water and step on the scale at the same time every day wearing the same clothing, you can measure the change in your body fat percentage. “Track your results and bring them to your doctor to interpret,” advises Kumar. Just don’t be surprised if your doctor does her own measuring at the office and comes up with a different number than what you’ve been seeing on your scale at home.

What number should you be looking for exactly? The average healthy woman (not an elite athlete or elderly person) should aim for a body fat percentage between 23% and 33% while men should shoot for 12% to 22%. While you’re at it, measure your waist circumference to stay on top of belly fat. “If someone carries a lot of fat in their abdomen, which actually carries more health risks, the scale is going to underestimate that number,” says Kumar. A healthy waist size is under 35 inches for women and under 40 inches for men.

The bottom line

So, if you love tracking your fitness data and sticking to a regular schedule, go ahead and buy a body composition scale. Use your measurements as a guide for your progress, but don’t depend on them completely and keep your doctor in the loop if you have any concerns. Now, go kick butt on those health goals for the new year!