Those who have never sought answers to the question before are often astonished by the many responses possible if one asks how to measure body fat. Body fat is essentially the percentage of your body that is made up of fat, and it is considered a critical metric nowadays for people who want to assess overall physical condition.
The basic formula for its calculation requires you to divide your fat mass by your total mass. The problem, as anyone will quickly note, is that it can be quite hard to obtain the figures necessary for that calculation. After all, you cannot very well physically separate all of your fat from the rest of your body just so you can measure it.
That said, there are in fact ways of measuring body fat. They do not all yield the same results and do not even have the same levels of accuracy which is why it is worthwhile to assess them individually in that respect.
Method 1: ADP
ADP stands for air displacement plethysmography. This is a method of estimating body fat percentages by calculation of the volume of air displaced from a special chamber when a person enters it. This method is not dissimilar to the hydrostatic weighing method which is discussed later on. Essentially, both of them rely on the displacement a body makes when it enters a place where the displaced matter can be measured.
This is a quick and painless method of measuring body fat, as it goes, but it is not widely accessible to most people. Furthermore, it cannot be done at home since it requires special equipment. It is accurate, though, at least if the subjects being measured fall within the middle range of the body fat spectrum.
Method 2: Anthropometric
The anthropometric methods cover a whole range of measurement techniques that most people can do at home. A widely used example is the skinfold method which makes use of body fat calipers (you can purchase these for home use for less than $10).
There are a lot of techniques for using body fat calipers. The essential way these work is that you use them to pinch a fold of skin from specific places on the body, then read the measurement on the caliper. Some techniques will require you to pinch skin from fewer than 5 parts of the body, others from more than that. All require you to average the resulting measurements and run them through a body fat calculator, many of which are available for free online.
The caliper method has its limitations, though. People who do not know how to use the tools properly will get inaccurate results, and moving the site of pinching too much will result in similarly varying measurements. It also does not work well on those who are heavily overweight as their fat can no longer be properly measured by the calipers.
Another option for the anthropometric technique followers is the US Navy method. With this one, you use a tape measure around your waist and neck (if you are male), or your waist, neck and hips (if you are female). The figures can be entered in a US Navy Method calculator or looked up for corresponding body fat percentages on US Navy Method tables afterwards.
This is perhaps the simplest anthropometric technique, but it is also the most suspect with regards to accuracy. People can have such vastly differing body shapes that it is difficult to come up with accurate estimates based on circumferential measurements like these.
Method 3: BIA
BIA stands for bioelectric impedance analysis, where a suitable device sends a very light electric current through your body to determine how much impedance the current meets. Why does that matter? Because fat impedes electricity more than muscle which has more water in it. People with more fat therefore tend to produce more impedance for the current.
This is one of the most used methods nowadays because of all the products coming out with BIA capabilities. A lot of digital bathroom scales are now being sold with BIA functionality, for example.
The beauty of BIA tools is that they typically no longer require a lookup of a specific method calculator or table if you use them. They simply deliver the body fat percentage to you themselves. The aforementioned digital scales will do this which means less work for you when you are trying to get this particular measurement.
Is it accurate, though? Reasonably so, although it can be swayed very strongly by how hydrated you are when you run the test. That is something to keep in mind when using this method for body fat reporting.
Method 4: DEXA
DEXA stands for Dual Energy X-ray Absorptiometry, and it is perhaps the most accurate of all the current methods. Basically, it allows the person running the test to divide your body’s mass into three parts: the mineral mass, the lean mass, and the fatty mass. The result is a very accurate photo of body fat percentage and even concentrations, as the scan reveals even that information.
There is a downside, however as DEXA is very expensive. It is also a method that takes a long time, as long as 20 minutes in some cases. This renders it highly impractical for the vast majority of people. That said, those who need a very accurate reading of their body fat percentage may well spring for the cost.
Method 5: Hydrostatic Weighing
Hydrostatic weighing is another of the very accurate methods available. It makes use of the fact that lean and mineral mass both have higher densities than water. A person dunked in water and having more fatty mass will weigh less in it while one with less fatty mass will weigh more. His weight in the water is taken as a factor in the formula used to estimate his body fat percentage afterwards which uses Archimedes’ principle for its calculation.
This method suffers from the same issue as the DEXA, however. It is costly to run and not available everywhere. This renders it another of the unlikely techniques for most people looking to get their body fat measurements.