What is Body Fat Percentage?
Body fat percentage is an important health measure – many would argue it’s even more important than just looking at body weight. This is because, when you really think about it, body weight is made up of a number of different factors:
- Body fat
- Water weight
- Skeletal structure
All of these contribute to how much we weigh. But, we know that having too much fat on our bodies can lead to more serious health problems later, like heart disease and type 2 diabetes. So, having your body fat tested is a great idea so that we know how much of your body weight is made up of fat cells.
Usually, the first place we go to get our body fat tested is our local gym. Normally, you would sign-up with one of their trainers and during your first training session with them, they will conduct some tests – like body fat testing.
But there are a number of ways to test body fat percentage and each is different as far as their level of accuracy.
5 Ways to Test Your Body Fat Percentage
Lucky for us, technological improvements have made the ability to test body fat very accessible.
I should mention that there are some very good reasons for someone to know their body fat percentage. This is because we can’t always rely on body weight to accurately determine whether someone is truly at their ideal weight. The amount of fat and muscle are part of this, of course, but so are our bones and organs and the amount of water we carry.
But when we step on a standard scale, the scale doesn’t know the difference between fat, muscle, our bones and water weight. It just tells us how much we weigh… period.
If you are really active and participate in a lot of strength training, you may weigh more than what health professionals expect. So sometimes, determining how much of a person’s body weight is composed of fat as opposed to muscle can be a more accurate measure of your weight status. This is also known as determining a person’s body composition.
There are lots of ways to measure body composition, but each has its pros and cons. They range dramatically in cost and availability as well as their own forms of measurement error. For each, the key is to make sure to follow instructions carefully in order to be sure that the results are accurate.
So let’s talk about some of the most common types of body composition tools and the pros and cons of each.
1. Hydrostatic Weighing
The most accurate forms of body fat testing are hydrostatic weighing and something called a “BOD POD.” (More on the bod pod below.)
Hydrostatic weighing is often called a “dunk tank.” That’s because this process involves dunking the body underwater and measuring body weight while the body is submerged.
To do this, the person sits on a bench that’s already submerged. The bench is attached to a special dial that measures your weight underwater. You climb into the water, make yourself comfortable on the bench, and exhale as much air as possible. This will cause the body to sink. Once you’ve exhaled as much air as possible, your weight is taken while you’re still under the water. Then, you come back up.
Believe it or not, this is considered the “gold standard” when it comes to measuring body fat percentage. Ultimately, the person’s “weight on land” is compared with their underwater weight. The entire process is based on the idea that fat causes us to float and lean tissue causes us to sink. The error rate is + 1.5%. That means your body fat percentage may be off by 1.5% in either direction. Let’s say, after this process, a person’s body fat is determined to be 12%. This means their actual body fat percentage may range from 10.5 to 13.5%.
Based on the special equipment required for this procedure, you can imagine that this test is not readily available. But, many local colleges and universities have this equipment and will schedule the test for a small fee.
2. Bod Pods
A BOD POD is becoming more popular and many gyms have them on-site now. This is based on a similar concept to hydrostatic weighing. Instead of using water, the Bod Pod uses air displacement to measure body composition.
Basically, you climb into this tiny little booth, the trainer closes the door behind you, and you sit there for a minute or so while the machine’s built-in computer system takes some measurements. These BOD PODS may overestimate or underestimate body fat by 2-3%. So, I would say the dunk tank and bod pods are usually most accurate.
The gym I used to go to had one of these set up in the back corner. It kind of looks like one of those old photo booths – you know the ones where you and your friends would insert 75 cents into the coin slot, cram into the booth, close the black curtain, and pose for 3 quick flash photos while making silly faces. Anyhoo, a Bod Pod kinda looks like this, except it’s shaped like a giant egg.
So, the person being measured sits inside a small chamber while computerized pressure sensors determine the amount of air displaced by the person. The entire process takes about 5 minutes. Because you don’t need to hold your breath underwater, this process is not as intense as hydrostatic weighing. It’s also pretty inexpensive.
As I said, many gyms actually have Bod Pods and will charge about $50 to run the test. But, it’s also not quite as accurate as hydrostatic weighing. Here the error rate is + 3%. So, again, let’s say someone’s body fat percentage is 12%. That means, their real body fat percentage could be as low as 9% or as high as 15%.
3. Dual Energy X-Ray Absorptiometry (DEXA) Scan
The test that’s probably least available is the Dual energy X-ray absorptiometry (or, DEXA) Scan. Just like the name sounds, this uses low-dose beams for X-ray energy to measure fat mass, where on the body the fat is stored and even bone density. The entire process takes about 15 minutes, but because this is a highly specialized machine, it’s usually only available at medical or research facilities. The cost of the test is about $300 and unfortunately, we don’t know how accurate it is. The % error rate is still being studied.
Alright, 2 more to discuss. These last 2 are the most readily available, least expensive, but most prone to error.
4. Bioelectrical Impedance Analysis (BIA)
One of these is referred to as Bioelectrical Impedance Analysis (or, BIA). Here, a low-level electrical current is passed through the body. The more electrical resistance detected by the analyzer, the higher the amount of body fat. This is because fat is considered to be a less-efficient conductor of electrical current. Whereas, in leaner individuals, electrical currents pass through with little resistance.
The cheapest and most convenient way to test body fat is using what’s called a “handheld BIA fat loss monitor.” These are the portable devices that you grab with your hands and hold straight out in front of you. After holding this device for about 10 seconds, the machine will perform some calculations and then display your body mass index (BMI) and your body fat percentage.
Because this type of machine is held in your hands, it really only tests the amount of fat in your upper body. So if you tend to hold more fat in your hips, for example, this may not be the most accurate test for you. Usually, this method may underestimate or overestimate your body fat percentage by anywhere from 3-5%.
There’s another device that uses a similar method, but uses a scale. With your bare feet, you step on the scale and it tests your body fat while it weighs you. This device is also called a BIA fat loss monitor but the difference here is that it’s measuring the body fat percentage of your lower body only. So some higher end gyms or wealthy trainers will use both the handheld and scale methods to test your body fat and average those to measurements.
When I used to see patients and train clients, I would carry one of these BIA machines around. You can find lots of these scales for sale on Amazon, like:
- RENPHO Body Fat Scale Smart BMI Scale Digital Bathroom Wireless Weight Scale (calculates 13 key body composition metrics)
- Omron Body Composition Monitor with Scale (7 fitness indicators and 90-day memory)
- Vitagoods Form Fit Digital Scale and Body Analyzer
You can also find these devices at WalMart, sporting goods stores…pretty much anywhere.
To improve the accuracy of the test, it’s important to follow the instructions that come with the machine. The error rate for BIA tests range from +4-6%. So again, if the machine says a person has a body fat percentage of 12%, then their actual value could range from as low as 6% up to 18% body fat.
5. Skinfold Calipers
Lastly, there's a form of body fast testing that uses skinfold measurements.
Sometimes, this procedure is called the “pinch test.” Have you ever pinched the fat around your hips or your belly with your fingers? Well, this procedure is basically that but, instead performing this on yourself and using your fingers, it involves an experienced professional using special skinfold calipers (which kind of look like smaller kitchen tongs).
The professional measures the amount of fat around specific areas of the body by pinching the fat that’s found directly under the skin and pulling it away from the muscle. They then use those special “tongs”, or calipers, to measure the thickness of the pinch. Once they have all their measurements, they then plug them into a special equation to determine body-fat percentage.
This is considered a fairly accurate test, WHEN IT’S PERFORMED CORRECTLY. So, finding a highly qualified and well-experienced person to perform this is really important to get the most accurate results. The cost of this test is up to the individual performing it. So, the cost can vary quite a bit, but most practitioners are pretty reasonable. If you have a well-trained practitioner administering this test, the error rate is +3.5%. So, 12% body fat may really mean that the person’s actual body fat ranges from as low as 8.5% up to 15.5%.
There are quite a few options for measuring body composition.
If you're looking for a definitive answer, it may be worthwhile to try two or more of the affordable methods and compare the results.
What's a Healthy Body Fat Percentage?
So, what’s a healthy body fat percentage? Well, it differs based on your age and gender. Think about it, women typically carry more body fat and that’s a good thing. This extra body fat not only promotes their health but, as they reach child-rearing age, it will help support pregnancy. For males, we can get pretty low on our body fat percentages without experiencing any health risks. For both genders, increasing age usually leads to increase in body fat percentage but that’s not always a bad thing either. So, here’s a general breakdown:
- If you’re female, 20-32% body fat is fine. The lowest you would want to go is 8%. Any lower than that, and you will likely experience something called amenorrhea, which means you will stop having your monthly cycle. There’s also risk for having lower bone density if you go below 8% body fat.
- For guys, 10-22% body fat is acceptable. But, because guys don’t rely on fat cells for producing as many of our hormones like ladies do, we can go as low as 3% body fat and still be ok. For reference, 3% body fat is what professional bodybuilders try and hit right before a competition.
Increasing Your Body Fat Percentage
What if you happen to be on the lower end of body fat percentage and want to build it back up? I realize many of us are trying to do the opposite and get RID of body fat as fast as possible, but there are those that have to follow special diets because of a preexisting condition. And for those folks, just maintaining their body weight and body fat percentage is important.
The best way to increase your body fat percentage is simply to eat more calories. But you want to be careful and not go overboard here. If you consume too many calories too fast, you’re going to probably make yourself feel pretty miserable and you may end up overshooting your goal.
I would recommend you aim to consume 100 to 250 extra calories per day. If you're on a ketogenic diet, this may be as simple as adding extra slices of avocado on your salad. For others that are not following this type of diet, you could add 1-2 tablespoons of nut butter on top of a piece of toast as a snack. It won’t take much.