– by 49% (Coach Joshua)
Well, we’re knee deep in 2018! The 2018 CrossFit Open and Friday Night Lights are over! My question to you then is this: What are your plans now, after the Open and Friday Night Lights? What are your goals for the next year? (If you’re having trouble with any of that, contact any Five Alarm coach and set up a Goal Setting Session ASAP!)
In the meantime, let’s tackle one of the most common goals we come across as the weather starts warming up…improving our nutrition and maybe losing a few pounds. Let’s assume for a moment that you’ve already got a plan (or plans) for that. You’ve already done some groundwork. You’ve got a plan that involves a sustainable “diet” and/or an exercise regimen that keeps you interested and excited, yet challenged. And you’ve even got a plan for being held accountable to those plans.
Now, my question is, how are you going to know if all of your plans are working? This would be when the majority of people would say, “I’ll weigh myself!” But what we REALLY mean when we say we want to lose (or even gain) weight is that we want to lose FAT (or gain MUSCLE), thereby reducing our body fat percentage and improving our body composition. So, how do we measure THAT?
Well, there are a handful of ways for one to measure their body composition. Below I’ve lumped the most common body composition analysis techniques into two groups, based on availability: Easily Available and Not So Easily Available. Please don’t get scared off by any fancy science terminology just yet!
Not So Easily Available
- Hydrostatic (Underwater) Weighing
- Body Mass Index Conversions
- Bioelectric Impedance Analysis (BIA)
- Skinfold Analysis
- Whole Body Air Displacement Plethysmography (Bod Pod)
- Dual Energy X-Ray Absorptiometry (DEXA or DXA)
Now let’s chat about each one…
Ultrasound. Ultrasound uses (shockingly enough) sound waves. With the right set up, machines can measure how fast the sound waves move through various types of tissue, thereby measuring the thickness of fat or muscle. If you do that on various points of the body, then input the results into an equation, you can get an approximation of a total body fat percentage.
So, what’s the problem? Ultrasound just really hasn’t caught on as a viable, easy means of testing body composition. At least, not around here. Machinery is expensive, and body composition testing isn’t the type of thing you just set up with an OBGYN. If anyone who reads this knows otherwise, please let me know.
Hydrostatic (Underwater) Weighing (UW). Take that name literally. You know the fruit scales you see in grocery stores? Little baskets that hang on little ropes or chains for you to weigh your fruit on? Picture a giant one hanging down into a giant tank of water. You sit on that, blow out as much of the air from your lungs as you can, and slowly submerge yourself completely. Someone outside takes the measurements – weight, water displacement, etc. It’s put into an equation and boom, body composition analysis. The good thing about UW is that is was once considered the “gold standard” of body composition analysis. If you wanted the most accurate and consistent measurements over time, you did UW.
So, what’s the problem? UW used to be available through Illinois State, and honestly I’m not sure if it still is. It’s not provided as an option on their website. But believe me when I say it’s not exactly a comfortable experience. Exhaling almost ALL your air and THEN going underwater isn’t pleasant. And you have to go under slowly, to minimize creating waves because waves mess with the giant scale. As the scale steadies and the tester gets a reading, they’ll tap on the side of the tank to let you know you can come up for air. Have to come up before that? Then there’s probably no reading, so do it again. And like everything in science, we like to get a few readings to make sure we’re as accurate as possible. Even with all that, there’s a standard margin for error of +/- 3 or 4%. Still, UW was considered the “gold standard” of body composition analysis for a long time.
Body Mass Index Conversions. Now we’re talking. No, not really. Ha ha. BMI is a horrible measure even before you try converting it to body composition. BMI uses two measurements, height and weight. No waist circumference or anything. Simple math shows that the more muscular a person is, the higher their BMI will be. Rich Froning is 5’9” and weighs 195 pounds. His BMI is 28.8, which is at the VERY top of their overweight category, and just barely under obese. We might not be as muscular as Froning, but we’re probably above average in the muscle mass category. More recent attempts at using BMI involve incorporating a waist measurement, and that does help somewhat. If you’re going to use BMI as a quick reference or guide, be sure to find a calculator that includes waist circumference.
Bioelectric Impedance Analysis (BIA). BIA is what you’re using every time you step on a bathroom scale that measures body fat or you use something like an InBody. Regardless of the tool, BIA sends a small, imperceptible electrical pulse through the body, and it reads the resistance of that electrical pulse through different tissue (muscle holds a lot of water, fat doesn’t). Combined with your weight and some more mathematical magic and voila…body composition analysis.
BIA has taken off in its popularity. For the most part because it’s exceptionally easy and convenient to use. But how accurate is it? Unfortunately, it depends. An accurate BIA reading relies on a lot of different factors, such as:
How much of your body the device is actually reading. For example, some scales will only shoot the electric current up one leg and back down the other, completely missing the top half of the body.
How hydrated you are. Dehydration leads to increased electrical resistance in the body, and therefore a higher body fat percentage.
What formulas are used for the actual calculation. We’ll see something similar in Skinfold Analysis.
In the end, BIA has shown to have a margin of error of around +/- 4 to 8%. Not so hot. But it is convenient, and is available here in Bloomington/Normal at Complete Nutrition.
Skinfold Analysis. Skinfold Analysis (SA) involves an individual using a specialized set of calipers to take measurements at various body sites. While Skinfold Analysis can be somewhat accurate (as low as +/- 3%), there are a host of factors that can contribute to inaccuracies. First, it requires an individual to be well versed in the proper technique used to take the measurements (the same individual should be used to take subsequent measurements as well). Second, how accurate are the calipers themselves? And third, there are literally hundreds of formulas to potentially use for SA. How many sites did the individual take measurements on (between 3-7)? Did they plug the results into a generic 7-site formula? Or a specific one for men? Or a specific one for men in their 40s? Or did they find the 7-site formula for caucasian males in their 40s with an athletic background? You get the idea.
Whole Body Air Displacement Plethysmography (Bod Pod). The Bod Pod works on the same concepts as Underwater Weighing, with the primary difference being that you’re not submerged underwater. Rather, you’re put into a small, egg-shaped pod that measures the amount of AIR your body displaces. That number is combined with your weight, body density, etc. – math, math, math – and you get a body composition reading.
However, none of this fancy technology makes the Bod Pod any more accurate than something like UW (which is still pretty decent). The Bod Pod’s primary benefit is its similarity in accuracy to UW, but while not having to be submerged underwater. Body composition analysis via Bod Pod is available through Illinois State University’s Exercise Physiology Lab by appointment.
Dual Energy X-Ray Absorptiometry (DEXA or DXA). A DEXA scan works by sending two different energies of x-rays at your body and measuring the absorbance of those x-rays through different tissues. IMPORTANT: These x-rays are very low energy, and the amount of exposure is less than that of a cross country flight!
First, the downside. DEXA can still be subject to a few errors. Of primary concern for most would be the level of hydration of the individual. Fortunately, it doesn’t affect the results as much as other methods. Aside from that, if different hardware or software is used on subsequent scans, that could play a part in the consistent validity of readings.
So, what’s great about DEXA? Like other methods, it’s very easy. Just lie still on a table for 5-10 minutes while the machine does it’s work. Also like many others, it will give you both your body fat and fat-free mass. However, unlike other methods, DEXA does two more things. First, it can break down your fat into body fat and visceral fat (how much fat you carry internally, around your organs). Good to know. Second, it gives you a THIRD metric: bone density. Very good to know. This makes DEXA the only 3-compartment model we have (fat, fat-free, and bone mineral). As such, it does not succumb to many of the errors other methods do.
In fact, DEXA is being viewed by many as the new “gold standard.” While one of the more costly analysis techniques, it’s not meant to be used on a super frequent basis, maybe every few months or so at most. The level of data and detail the scan provides is unparalleled for body composition analysis methods, and it’s margin of error tends to be very low, at only +/- 2 to 4% or so. Bloomington/Normal recently obtained a DexaFit facility, which does not only DEXA body composition analyses, but also VO2 Max and Resting Metabolic Rate testing.
“Enough already!” you say, “What exactly do you recommend then?”
Well, it depends. In spite of all the information above, it is my belief that for the vast majority of people, knowing your body fat percentage doesn’t improve your life in any meaningful way. Instead, I like to tell people their top three factors should always be how do you look, how do you feel, and how do you perform (in life and/or sport)? Then, if you’re focused on making a change and want some concrete numbers for comparison, we can add in outside measurements.
Let’s start with some easy items… Take a few “before” pictures. When you see yourself every day, change is hard to notice, and those pictures will show you really just how far you’ve come. Also, how are your clothes fitting? If you’re trying to lose weight, are they looser? If you’re trying to gain muscle, are they tighter in the right places? Circumferences and body measurements can be extremely useful to show things like inches lost, or how much mass you’ve put onto specific body parts. Even body weight from a standard bathroom scale can be useful, especially if used in conjunction with the simple items mentioned above.
Then, occasionally, if you so choose to, throw in a body composition analysis. Just remember, body composition analysis is just a tool. It doesn’t make or break you. All the methods have potential benefits and drawbacks, and only you can decide which method will be best for you. I hope you’ve found the above information useful! If you have any further questions, you can email me firstname.lastname@example.org!