You may already know that on their own, your weight doesn’t mean much; different frames, different ages, different muscle masses all make weight useless in a vacuum. Your BMI may seem slightly more useful, but it’s more of a population-analysis tool, not a tool for looking at individuals. What we need to look at to gauge our bodies, to determine without a doubt how healthily composed we are, is body fat percentage. Today, we’ll talk about methods of measuring body fat, what we should expect to see, and how that data can help us make better decisions in controlling our fitness.
What To Know About Body Fat
Methods of measurement
There are several methods available for measuring your body fat, ranging from basically guesswork to scientifically precise; typically, something in the middle’s going to be the best balance of accuracy and convenience, but even the most inaccurate solutions have their use (more on that later).
- Impedance. Impedance tests, like the ones you might use at a drug store health kiosk, measure body fat percentage by calculating your body’s resistance to an electrical current; different tissues resist electricity differently, allowing for a rough estimate of body composition. Unfortunately, factors such as hydration levels can seriously change your outcome, making this a dubious tool for accurate numbers.
- Calipers. One of the simplest ways to measure body fat. By measuring skin folds with calipers to determine subcutaneous fat, we can estimate total body fat percentage. Surprisingly, this offers more reliable body fat estimates than impedance testing. Make sure you’re using measurements from across your body and not just one or two spots.
- Plethysmography. We’re entering the more scientific realm now. A so-called ‘bod pod’ can be difficult to find, but allows you to get extremely accurate body fat percentage measurements based on air displacement. If you have easy access to one, this can be your best option, but the next two are far more common.
- Underwater weighing. It’s a bit annoying, but if you’re willing to get wet underwater weighing will give you very accurate readings (and there are far more places to get proper body composition readings with this method than air displacement). The principal is the same as plethysmography; displacement varies with body composition, allowing an accurate measurement of your body fat, muscle, hydration, etc.
- DEXA. Expensive and hard to find, DEXA scans utilize x-rays to give a section-by-section analysis of your body composition. It’s extremely accurate and very useful for seeing not only fat deposits, but muscle concentrations—useful if you’re trying to figure out whether you’re bulking up in a certain area a good way or a bad way!
What you should expect
Body fat expectations vary by gender, as women have more ‘essential fat’ they can’t lose while remaining healthy. Generally speaking, men don’t want to go below 6% body fat, and women don’t want to go below 14%. Past that threshold, you’re playing with fire—some men can go as low as 2% and women as low as 10, but this is based on a number of factors and is largely unnecessary. On the other end of the spectrum, men are considered ‘obese’ past 24% body fat, and women past 32%. Depending on the standard you use, older men and women have some leeway as their body composition naturally changes to higher fat percentages.
Using the data
If you’re in the obese range, you likely already know what to work on: exercise more, eat less. Generally speaking, the latter is a bigger factor in shedding fat, so don’t ignore diet just because you’re working out hard. If you’re at the other extreme, and haven’t already been tracking body fat %, you need to either educate yourself thoroughly on being healthy with minimal body fat, or take your training down a notch—even professional athletes usually clock in at the 6-13% and 14-20% ranges for men and women respectively.