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What’s The Best Way To Measure Body Composition?

By Alexander VanHouten, Master Trainer & Life Time Education Specialist

“I don’t want to measure today. I don’t feel like I’m making progress.”

Though my clients would say my empathy as a trainer is reliable and appreciated, they will tell you that I have exactly zero sympathy for fearing numbers that may indicate progress…or lack thereof.

In fact, if you feel like you’re not making progress, that’s exactly why we need to measure!

Is the program working? Is it not? What effect did your poor choices this weekend have on your body? What effect did your cardio consistency have that you may not be able to see for yourself in the mirror? The important questions go on and on.

These are questions that need answers if I’m going to help you get anywhere.

But it’s not the fear of necessity that drives people from stepping on the scale or letting me put a tape measure around their waist. It’s the lack of understanding about what measures matter, confusion about expectations for realistic changes, and what these measures actually mean.

“To understand something is to liberate yourself from it” – Unknown

Let’s understand your body composition measures.

Measures worth tracking

Self-actualizing fitness goals require some serious soul-searching to set and begin taking steps toward.

However once you begin, in order to ensure that you’ll continue to make progress, you must be able to answer the all-important question—

How will I measure my progress?

Even more importantly,

Though there are some very discussion-worthy measures related to “Vitality and Health” goals (like being pain free or reducing or nixing medication dependence) or “Performance” goals (like improving my deadlift or running a faster mile), I will focus today on “Body Composition” goals (like toning, fitting into clothes, losing weight, looking better naked).

Let’s talk about weight, BMI, girth, calipers and body fat.

Weight

Scale weight. The amount of force you exert upon mother earth, thanks to gravity’s pull, is measured in pounds or kilograms in most of the industrialized world. This is the number one misunderstood measure by the average population that I’d like to clear up.

Why it matters? There are so many subjective reasons this number matters to individuals. But most of them can be described by the other measures I will talk about today. Mainly it’s simple, concise and we all have a “fighting weight” that we are emotionally connected to.

What is your “Fighting weight?” We all can remember a time in our lives when we felt the best or looked the best or were all-around happiest with our body’s appearance, abilities, and energy.

I won’t argue with this anchor in your mind. It’s important to you. I get it. Just don’t blow it out of proportion.

Why it doesn’t matter. Weight doesn’t tell you your dress size. Weight doesn’t tell you how much of you is fat or muscle. Weight doesn’t tell you how healthy your organs are. Weight doesn’t tell you about your libido, your sleep cycle or your nutritious eating habits. Weight doesn’t really even tell you how long you’ll live or how you’ll feel with the years you have left! You get the picture.

Kind of like the number of calories you eat in a day, weight simply doesn’t give you much information about WHAT the pounds are actually composed of.

How much of you is water, type-1 muscle, type-2 muscle, visceral fat, subcutaneous fat, brain matter, organ tissue, blood volume??

In fact, the weight measure is so largely irrelevant to a client’s body composition progress in the first phases of training, that I tell clients I don’t expect to see ANY changes to this number in the first month.

You see, your weight is a number that represents an overall equilibrium. It accounts for countless fluctuations and specific pieces of information without actually revealing much. So with regard to body composition goals, your “fighting weight” only makes an important appearance in our progress discussion around month two or three.

It takes time to establish a new equilibrium. In the meantime, let’s talk about some other measures…

BMI

Your mass divided by your height squared (generally in kg and meters respectively). Your BMI is another commonly misunderstood number. Body mass index is a statistical tool that attempts to add significance to the relatively useless weight number.

Why it matters? For general purposes, BMI is a useful measure to add color to the potentially negative health effects of obesity. You can find the history and limitations of this measure laid out for your review here.

Why it doesn’t matter? For individual fitness goals, BMI is about as useless as weight in measuring progress for the reasons I’ve already stated. Since your height doesn’t change much in adulthood, regardless of your training regimen, all BMI change indicates is that weight is changing.

Unless your fitness goal culminates in “I’d like to save money on life insurance”, then I don’t recommend tracking BMI as a measure of your body-composition-improvement-program’s effectiveness.

Girth

Yes, Girth is a word. And it’s important. Girth describes the circumference of particular parts of your body. You know, the old tailor’s measuring tape that wraps around your waist, hips, calf, thigh, chest, neck, upper arm, and forearm. Lots of girths to choose from!

Why it matters? Girth is often the best and most simply measured indication of muscle growth in your extremities and fat loss in your midsection. And it directly reflects your clothing sizes —which is a very important objective measure of what many remember their “fighting weight” to be!

Think about it, which is more impactful to say?

“Yeah, I’ve lost 5 pounds in the last 4 weeks!” or “I’ve lost 5 inches around my waist this month!”

I rest my case.

Why it doesn’t? Though girth is a great way to objectively measure whether you’re getting bigger or smaller in different parts of your body, it is not a very helpful way to measure body fat percentage.

There are some mathematical equations derived from girth that will let one estimate body fat percentage from girth. However when measured against the DXA (Dual-energy X-ray absorptiometry) scan or hydrostatic weighing (the gold standards for body composition assessment), these equations aren’t even considered diagnostically accurate enough to be used in practice.[i]

So don’t use girth to tell you how much body fat you’ve lost.

Calipers

Ready to get pinched? Calipers are the tool fitness professionals use to measure how many millimeters of subcutaneous (under the skin) fat there is between your muscle and skin. Although there isn’t much else in the gym that’s more uncomfortable than a 7-site caliper assessment, (except maybe single leg BOSU burpees) it can give you valuable insight into some very important information about your body composition.

Why it matters? Caliper measures are more complicated to take than girth measures. There are precise directions and positions for each location to make the measure meaningful. But these measures quantify how “toned” particular parts of your body are getting and can be used to identify if there are any parts of your body that are not changing along with the rest of you, so that necessary adjustments can be made.

For instance, if I have a client whose caliper pinches are decreasing everywhere except the midsection (the umbilical and superiliac pinches as they are called), then I can use this information to pinpoint what changes need to be made to their program to ensure their body continues to progress proportionally and consistently.

No one wants toned arms and a mushy tummy. (So many have this problem that I wrote a whole article on it. Check it out!)

Why it doesn’t? Though calipers can reveal an amazing amount of information to the body composition assessment, one of their common uses is to calculate body fat percentage.

With technology today, there are simply easier, more reliable and more consistent measures of body composition than the various mathematical estimations of Caliper Body Fat Equations and Tables. Use calipers to show you specific progress and laggard areas in your body composition journey and leave the body fat measures to even more objective sources.

Let’s talk about that next!

Body Fat Percentage

What percentage of your body is currently composed of mostly sluggish, metabolically-draining, cottage-cheesy extra mass that just isn’t necessary? Great question. In fact, unlike weight or BMI, this number is a highly personalized, all-encompassing measure of body composition that is the gold standard for tracking progress or lack thereof.

However, pinning this measure down accurately has been a journey in technology, mathematics, convenience, confusion and research. This has been driven by the fact that it is rightly heralded as the measure that should be used for understanding true health and fitness in the face of the obesity epidemic.

An interesting side effect of the study and refinement of taking this measure cost-effectively is that researchers are warning that true obesity rates are actually higher and growing faster than originally thought, due to the relatively inaccurate nature of BMI measures for all but the morbidly obese.[ii]

Why it matters? When measured accurately, body fat percentage is an all-encompassing look at how much of your body is essentially unnecessary baggage that you’d do well to rid yourself of. Since healthy ranges of body fat percentage have been conclusively established both for athletes and the general population by gender and age, this measure gives you something to shoot outside of “what you think you should be”.

And with a little calculation, you can use body fat percentage to tell you whether your program has helped you put on lean body mass. You know, the helpful, strong, sexy-looking kind of body mass that can actually do cool things.

When measured accurately, this is the single most-important progress metric in a body composition program.

Why it doesn’t? I really can’t think of any reasons your body fat percentage doesn’t matter. Unless you traveled to the future and somehow had your brain implanted into a machine so that you could live for eternity as some non-organic entity who doesn’t need to concern itself with body composition because you could easily add or remove any augmentation you desired…I guess then it wouldn’t matter.

Here in the present, if you have body composition goals, Body Fat Percentage matters. End of story.

Go Get Measured!

I hope you see there’s no reason to be scared.

Now that you understand weight, BMI, girth, calipers, and body fat percentage, you can be free to assess them regularly and watch yourself progress or modify your program when you’re not progressing.

You know what it all means now. So all there is left to do is get these measures done for yourself!

And then we’ll work on creating the delta.

[i] Wells JCK, Fewtrell MS. Measuring body composition. Archives of Disease in Childhood. 2006;91(7):612-617. doi:10.1136/adc.2005.085522. Available online: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2082845/

[ii] Julie A. Pasco. Body mass index and measures of body fat for defining obesity and underweight: a cross-sectional, population-based study. BMC Obesity. 2014 1:9. DOI: 10.1186/2052-9538-1-9. Available Online: https://bmcobes.biomedcentral.com/articles/10.1186/2052-9538-1-9

The posts on this blog are not intended to suggest or recommend the diagnosis, treatment, cure, or prevention of any disease, nor to substitute for medical treatment, nor to be an alternative to medical advice. The use of the suggestions and recommendations on this blog post is at the choice and risk of the reader.
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