How to Measure Your Body Composition
Body Composition is important to measure your health and also determines the way your body looks.
To learn why Body Composition is more important than BMI (Body Mass Index) see my article on BMI vs Body Composition.
As you can learn in that article, BMI is only a very rough gauge as to the fat level in your body, and is bound to be flat out wrong when judging someone with a lot of muscle or very little muscle.
A far more accurate way to gauge your health, and how attractive your body appears, is to measure your Body Composition.
Body Composition might refer to many things including bone mass, organ mass, and water weight, but the two things we mainly concern ourself with in fitness are muscle mass and fat mass.
When your muscle mass and fat mass are each in their healthy ranges, you are far more healthy than when the numbers are either above or below their healthy ranges.
To learn what Body Composition numbers are healthy for you, see my article on Ideal Body Composition Numbers.
Now that we know the differences between BMI and Body Composition, and know what our Ideal Body Composition Numbers are, we're ready to learn how to measure your body composition. Then we'll talk about how to calculate the difference between your current composition level and your ideal composition level, and then learn how to make the appropriate adjustments to them.
Measuring Your Body Composition
There are several ways to measure your body composition
Scale + Scanner
Tanks and Pods
A caliper is a small device which measures the size of an object from opposite sides.
These can be used to measure body fat in an individual by reading their skin folds in several places, depending on which technique you use.
Accuracy: Calipers are as accurate as the person providing the test.
If you're testing yourself, consider seeking instruction from someone professionally trained in how to use calipers to make sure that you are getting the best possible measurement, or do research on how to use them on yourself correctly.
Getting a buddy to help you practice can also get you in the swing of using calipers.
I think electronic scales are a great way to measure your body fat, as they have a low friction level to use. You don't have to learn how to use tricky devices, you can't make small mistakes in your measurements, and they usually report results in just a few seconds.
These scales use Bioelectrical Impedance Analysis to measure your Body Composition. Muscle and fat each have a different resistance to electricity, due to the amount of water in each of them, so a tiny amount of electricity (which you can't even feel) passes through your body, and the scale makes a decently accurate guess as to your body fat percentage, and perhaps other stats.
Accuracy: The biggest issue with getting accurate readings with electronic scales is the quantity of food and liquid in your system. You can mitigate this issue by taking scans after you wake up each day, as opposed to a random time during the day, as your body will be the most consistent at that time.
I also recommend averaging the results over several days. For example, you if your body fat percentage reads 20.3% one day, 19.9% the next, 20.8% after that, and finally 19.6%, your average is 20.15. This reduces the false high readings on days when you have more water retention due to extra sodium in your diet, or vice versa.
Another issue with accuracy that I find makes people encounter issues is placing the scale on something other than a solid surface. If you put the scale on carpeting or rugs or anything other than tile, linoleum, hardwood floor, cement, or anything else completely solid, you will get inaccurate weight readings. But this tip goes for all scales, not just bioelectrical scales, unless the scale states otherwise.
Finally, more data = more useful information. Each measurement on a BIA scale may not individually be accurate (fluctuations due to food, water, sweat, duration since exercise, duration since sleep do cause errors) but the more readings you have, the more you can see how your numbers are adjusting, which is more important than getting an individually accurate reading. Does it matter if your fat % is 26% or 27%, when you know that it will be healthier 10% lower, either way? When you see the number trending down (26 or 27, then 24 or 25, then 22 or 23) you know you're making the right decisions.
There are a lot of scale on the market that measure your body fat, and some other stats as well. I review the two that I've used, below.
Omron HBF-516B Body Composition Monitor with Scale - 7 Fitness Indicators & 90-Day Memory
The Omron Body Composition Monitor gives me 7 different indictors. I've been using it for around 6 years now, and find that the readings are fairly consistent, provided you look at an average over a few days, and take your measurements at the same time each day.
The 7 measurements it gives you are Weight, BMI, Body Fat %, Body Muscle %, Resting BMI, Body Age, and Visceral Fat.
Weight is accessible on any other scale, while BMI is a not-very-useful stat that just takes a division of your height by your weight to reach.
Body Fat % and Body Muscle %, and Visceral Fat, however, help you discover your overall health level, and tracking their change over weeks based on your physical activity can help you learn a lot on how to get healthy.
See my article on Why Lose Fat to learn more about the great importance of Visceral Fat.
Under Armour Healthbox
The Under Armour Healthbox is a kit of three devices made by UA. It comes with a scale, a band for your wrist, and a heart rate meter that goes on your chest.
The scale gives less information than the Omron (weight and Body Fat % only), however it does upload the information automatically every time you step on it, and you don't have to tell it which user you are. It can remember up to 8 users, and recognize you when you step on, and the data is accessible from an app on your iPhone or Android, with a history, graphs, trend lines, and more.
It also comes with a year Premium membership to MyFitnessPal and MapMyFitness, and the UA Record app used buy Healthbox syncs with those apps.
When you log a work out with UA Record, the calories from the workout are automatically sent to MyFitnessPal, and your remaining calories to eat during the day are updated. There's a setting which allows the nutrient goals to be updated also; for example, if you work out, you'll need more protein, and the app will reflect that.
Scanners such as DEXA (or Dual-Energy X-Ray Absorptiometry) are specialized scanners that use X-Rays to determine your fat and muscle percentages, but have notorious error rates, and are expensive to access.
Scale + Scanner
A new technology is coming soon which integrates 3D scanning and a scale to measure your Body Composition.
Designed by Naked Labs, the Naked 3D Fitness Tracker's polycarbonate scale with frosted glass top will turn you 360 degrees around in front of a mirror with embedded 3D scanners which analyze your whole body and deliver a detailed report of not only how much fat and muscle you have, but where the fat and muscle is in your body.
The scale isn't out yet, but I backed this project a while ago, and if you go to sign up with them and use code SARENAS you will get $50 off the system!
Tanks and Pods
Hydrostatic weighing tanks and air pods use water displacement and air displacement to figure out the volume of your body. This is compared to your weight, height, and gender, and an estimation of your body fat percentage is offered.
They are expensive and inconvenient to use, and most people won't use them unless they are training as a professional athlete.