Body Fat Percentage

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The traditional metric in medicine has been using BMI (body mass index) for a measure of physical fitness. This metric uses only your height and weight to determine if you are obese or not. The problem is that the metric is very flawed as it doesn’t correct for body composition. For instance, I have been “overweight” since I have been physically fit, but there are a few times I have measured as “obese” because of my muscle mass (usually at the end of my mass gaining phase when I am carrying a little extra fat around too). I don’t think anyone would look at me and think I am obese. The best metric to use is one that should include body composition as it is the increasing body fat percentage that is the problem in medicine. The problem with using body fat percentage as a metric for physical fitness is that we don’t yet have an EASY way to accurately obtain it. In the following paragraphs I will discuss how to measure your body fat percentage and what your goals should look like depending on your gender and personal goals.

Before we even jump into ways of measuring your body fat I should make sure that everyone understands that there are certain levels of MINIMUM body fat required to safely operate your body. Once you go below this threshold you can start to develop problems if you stay below it for prolonged periods of time (reason number 36 why bodybuilders and professional actors/actresses don’t always look as good as they do in the movies or onstage). Fats are required by our body to make almost every type of cell and also to produce our hormones. For the average man this number seems to be around 8%. Less than that would be considered unhealthy if done for a prolonged period of time.

For men 8% to 20% is a healthy body fat percentage (you will likely have noticeable fat collection toward the 20% mark). An athlete could be fine with as low as 6% (prolonged). 20-25% is considered overweight and over 25% is considered obese (see how fast that escalated?). These numbers also change with age as we require a little more body fat to make these hormones (that are now much more scarce than they were in our younger years). In our 40-60 window you can add 2-3% to all of those categories. For greater than 60 years of age you can safely add another 2-3% to all of those categories. Men have a genetic tendency to store most of their body fat in the abdominal region.

Women require a slightly higher body fat percentage for many reasons and also simply measure higher because of their breasts. For the average woman 21% seems to be the magic number. If you are very athletic that number can be as low as 14-21% (some women are quite slim from a genetic standpoint and don’t have large breasts and their numbers will be skewed slightly from this). 21-33% is considered health in a woman. 33-39% is considered overweight. Greater than 39% is considered obese. As with men, the older we get the more body fat percentage is required. In the 40-60 year old age range you can add 1-2% for each end of the range on each category. Greater than 60 years old is another 1-2%. Women (on average) have a genetic tendency to store body fat in their legs, hips and butt.

The cheapest way to measure your body fat is to use Calipers. This is also the crudest way to measure body fat and is largely susceptible to water retention and human error. Most calipers will come with instructions on how to calculate your body fat and where/how to take measurements. I have personally used these before and taken an average with the next measurement I will present. The most important thing to remember is to take the measurements in the same spots, the same way (maybe even have the same person help you, however you can do it yourself, it’s just a lot harder to read it).

The next best body fat measuring method is bioelectrical impedance. These are the scales you can buy that allow you to measure body fat. They are generally more expensive than calipers (but not very expensive for a basic one like this scale), but if you’re already in the market for a scale I would recommend buying one that measures body fat. These work by sending an electrical “signal” from the feet (and hands for some models) into the body and measuring how fast it returns (no, you don’t get shocked and you won’t even feel it). The accuracy of this is slightly better than calipers in general, but still not very accurate when compared to the high end methods of measuring body fat. I have found my body fat percentage to be fairly close to that of the calipers when compared, but is significantly quicker and less taxing. I take this number with a grain of salt. I know its likely not super accurate, but its the CHANGES you are tracking. I step on my scale almost daily and keep track of my weight. As long as the numbers are going down I keep it simple. About once a month I will get completely naked and stand on the scale to measure my body fat percentage. Body fat percentage is not something you want to track every day because of the level of inaccuracy of these machines. The scales that have a handheld device WITH the scale are more accurate (such as this scale), but also tend to cost quite a bit more. Don’t get the handheld only version because they are less accurate than their scale counterparts and you can’t get your weight from them either. The importance here is to attempt to obtain the measurement in the same “state” every time. If your feet are wet and you’ve just gotten out of the shower, make sure you are doing that every time. I do it first thing in the morning, after a pee (and possibly poop), before I shower and definitely before I eat or drink anything. This will give you the most accurate measurement (some scales recommend your feet be damp/wet, but I have noticed the difference to be minuscule to nonexistent). I recommend you test your scale and step on it about 3 times to make sure you are getting basically the same percentage each time. That way if the scale says 21% you will know that you are likely not at 21% but if it says 20% in a month or so you are indeed losing body fat.

Hydrostatic weighing is one of the most accurate options for determining your body fat percentage. This is done by comparing your normal weight to your weight when submerged under water using an equation. The most accurate methods take into account the density of the water you are in and your functional lung reserves (amount of air in your lungs after maximal exhalation) as these factors will impact your underwater weight. As you can imaging it is not the easiest thing to do and there are not a lot of places where it can be done. I have recently moved into a house with an in-ground pool and I fully intend to design my own method of hydrostatic weighing. If it is successful I will share my process with all of you (just a quick note, it requires you to be naked for the best accuracy).

There are various other methods that are pretty accurate, but either very expensive or relatively inaccessible to the general public such as DEXA Scans, Air Displacement Plethysmography, etc. My overall recommendation is to get either a decent scale that measures body fat and focus on the CHANGES not the actual numbers or get a set of calipers and again focus on the changes only. If you’re a real go-getter you can do both and take an average like I have done in the past.

I tend to stay in the “healthy” category for body fat percentage. Once I hit or approach one end of the spectrum (8% or 20% for men) I tend to change my diet to start going toward the other end (going on a cut or a mass gaining phase). This enables me to keep most of my hard-earned, fat-torching muscle and not let my body fat get out of control. Plus it’s good for your sanity and body to change up your diet/eating habits as it breaks up the monotony that comes with fitness sometimes. You can make your window as narrow as you want (8-14% for instance), but just make sure you aren’t gaining or losing too fast or you will confuse your body and it’s hell on you to change up your diet and eating habits that often. It will take time for you to find that sweet spot where you feel comfortable, but you’ll never know that sweet spot if your not measuring your body fat percentage.

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