Body Composition – Measurement Methods

In previous parts of this guide I’ve looked at what body composition is, showed you how to do various body composition calculations and looked at various body composition numbers.  Consistently in the comments section of each article there has been at least one question asking how I suggest people measure body composition; as promised I’m finally going to answer them.

Measuring Body Composition

There are a number of reasons to measure body composition.   Arguably the primary one is to track the results from any diet or exercise training program.  As a trainee seeking body recomposition, the goal is to lose fat, gain muscle or both.

Only by tracking body composition can you know if what you’re doing is working.  There are other reasons such as health or simply vanity as well.  None is more valid than any other and I want to look at methods to track each.

So today I want to look at various methods of measuring and tracking body composition (or changes in body composition).  These range from low- to high-tech and from extremely useful to useless (or at least impractical)  Technically the first set methods do not measure body composition.

Rather, they provide a variety of methods to track results that can be useful in addition to any direct measurements of body composition.  They also tend to get discussed quite a bit in popular media.  This will give you a background to know if what is being discussed is correct or not.

True Body Composition Measurement Methods

Let me first look at methods that measure body composition per se.  By this I mean they provide an estimate of body fat percentage (which can be used to calculate body composition) or the amount of fat and lean body mass (LBM) present.

For no real reason I’ll move from lower to higher tech (more or less) as I go examining body mass index (BMI), circumference measurements, underwater weighing, calipers, Bio-Electrical Impedance Analysis, Infrared Reactance, the BodyMetrix 200, Bod Pod and finally DEXA in terms of how they measure body composition.

Body Mass Index (BMI)

While BMI is traditionally used as a rough measure of “health”, it can also be used to get a rough indicator of body fat percentage.    I’ve presented this method in two of my books, The Rapid Fat Loss Handbook and A Guide to Flexible Dieting and calculators can be found online as well.

Let me emphasize that this method can ONLY be used by people who have not been training. Anyone who has been consistently exercising for 6 or more months cannot use this method as increases in muscle mass will skew the values completely.  For beginners or those not exercising, using BMI provides an easy, albeit rough, estimate of BF%.

Circumference Measurements

While tape measurement/circumference measurements are more commonly used to track changes in inches of various parts of the body, methods exist to use them to estimate BF%.  Many books use this approach because it tends to be simpler and faster than other methods.  When large groups of people have to be tested (such as in the military), it also provides a quicker way to get a rough idea of where everybody stands.

Now, somewhat surprisingly, some of these equations actually give decent estimates of body fat percentage.  Not perfect, mind you, but as I’ll discuss in another article, no method is perfect short of full-body dissection (and you can only do that once).  They will at least get folks within shooting distance.

Now, the various methods and equations that use circumference measures vary quite a bit.  Some of them use circumference along with weight/height, some use circumference measures with a couple of caliper methods, there’s a lot of variance.  How accurate these various systems are tend to depend a lot on what sites are being used.  This also varies quite a bit.

One thing to consider is that, depending on the method, a large bone structure or heavy muscle mass can throw off the numbers quite a bit.  I had a client years ago who had a particularly wide hip structure and one circumference method that used hips estimated her at a far high body fat percentage than she actually was (based on calipers).

One equation uses the neck and I’m not sure how it can separate people with a lot of fat on their neck and folks who have built up a lot of muscle there.  I think you get the idea.

 

Underwater Weighing

Underwater weighing is often described as the “gold standard” for body composition measurement and, in some ways, I probably should have led off this piece with it.

The reason is that underwater weighing is usually what’s used to determine the accuracy of other methods.  So researchers will underwater weight a bunch of people and then measure their body composition in some other fashion (e.g. calipers, circumference, etc.) and that’s how they develop the equations for the other method.

Basically, it’s assumed that underwater weighing gives the ‘correct’ value for body composition and the other methods are developed so that they give the same values.

For a while underwater tanks were very popular and could be found in a lot of different places. Lately they are only found in performance labs at universities for the most part. There’s a reason for that which primarily has to do with the hassle involved in doing it.

The basic premise of underwater (or hydrostatic) weighing is that “fat floats”.  Ok, it’s a bit more technical than that but that’s the gist of it.  Basically, different tissues in the body have different densities, and they will all have a relatively greater or less likelihood of floating in water.

Very strictly speaking, underwater weighing is estimating what’s called body density, that is it tells you what the average density of the tissues in the body are, that goes into a separate equation that converts body density into body fat percentage.  But that’s getting a little bit more embroiled in details than I want for this article.

To get underwater weighed, you report to the lab in your bathing suit. First they weigh you out of water, then you get into the tank (filled with cool but not cold water). Then you breath out as much air as possible and then dunk your head under and let them weigh you again.  The difference in your weight on land vs. underwater allows them to do a bunch of neat calculations and determine body density.

However, there are problems with underwater weighing.  One is that few can blow all of the air out of their lungs before dunking their head underwater (would you do it?).  I suppose if you find the idea of suffocating fun, maybe.

But for most people, some air will be left.  This is actually pretty important as gas floats and air in the lungs will cause folks to be ‘lighter’ underwater.   Amusingly, one study found that a big gas producing meal, containing beans, threw off the measurement.  I guess beans really are good for fat loss.

Even then, it’ s impossible to get all the air out.  Humans simply can’t do it.  So researchers use other methods to try to measure (or at least estimate) how much air is left but this just introduces another potential source of error.  Some methods let you keep your head above water but this too reduces accuracy.

Finally, relatively speaking, underwater weighing tends to be somewhat pricey; as noted tanks are usually only found in performance labs these days.  Since you have to do at least two measurements to see if a diet is working, this can add up quickly.   Unless you have a friend in the exercise physiology lab who can get you in cheap or free, I’m not sure that there’s much point.

It might be useful to get a caliper measurement done and get dunked on the same day to see how close to reality the calipers are. But that’s about it.

Skinfold Calipers

Possibly one of the most common methods for measuring body fat percentage are calipers.  Calipers are small spring loaded devices that have been used for literally decades to measure body composition; given a few criteria are met, they are surprisingly accurate (that is, giving values similar to underwater weighing).

The reason is that a rather large majority of the body’s total fat is found underneath the skin (there is also visceral fat which surrounds the gut).    This is a big part of what lets calipers be fairly accurate: since you can get to the fat that is under the skin (measuring visceral fat takes more complex methods), you can measure it.  That’s what calipers do.

When making a caliper measurement, specific sites on the body are used and very specific methods are used to make the measurement.  As with circumference measures, folks who worry about this stuff, spend a lot of time being very specific about where and how to take the measurements to get accurate results.

The basics of caliper measurements are:

1. The person doing the measurement pulls the fat away from the muscle so that the sides are parallel, and applies the calipers, which give the thickness of the skin fold in millimeters.
2. Readings are taken after 2 seconds (this is important, if you wait longer, the caliper will squeeze water out of the area and give you an artificially lower reading).
3. Three readings are taken at each site and they should be within one-two mm of one another. If they aren’t, the results won’t be accurate and the skin fold should be re-measured.
4. Between readings, a short break is given to avoid squeezing water out of the area, otherwise you get progressively smaller measurements as you go.

Anywhere from 3 to 10 (or more) sites may be measured to get an idea of total body fat percentage and distribution and, the last time I looked anyhow, a total of 19 sites have been described in various studies. Traditionally, the right side of the body is measured, I have absolutely no idea why this is the case.

Typical sites include triceps, biceps, abdominal, iliac crest (love handles essentially), subscapular (underneath the shoulder blade), axilla (under the armpit), pectoral and thigh.  You’ll sometimes see calf and chin or a few others in there.

Perhaps the oddest skinfold site I have seen is the hump; apparently some of the HIV drugs cause a fat redistribution to the back of the neck and researchers are measuring the fat hump to track changes.

Once the chosen number of sites has been measured, the numbers (which are in millimeters of thickness) are totalled and plugged into an equation, usually along with age.  This cranks out body fat percentage.   As I mentioned above, technically speaking, the equation spits out body density, which goes into a second equation to give body fat percentage.

Various equations an be found online and each have their pros and cons.  Equations using more sites tend to be more accurate but give the person doing the calipering more opportunities to screw up.   Equations using fewer sites are faster but can drastically mis-estimate body fat percentage if they don’t measure a place where a given individual happens to carry a lot of fat.  So there are always trade-offs.

In terms of equipment, calipers can vary massively in both range in price.  Clinical models, as used in research studies, such as Lange and Harpendon will run to $200 and there are even electronic models such as the Skyndex which has the estimation equations built into them; those will run you about $400.

I imagine everybody has seen the home versions which can often be had for $10 or so, they are often packaged with books because they are cheap.  I don’t think they are very accurate though, slight differences in how quickly you squeeze the calipers can drastically affect the measurement you get.  I do not recommend these even if they are super-cheap.

My standard suggestion for people who want their own calipers are the Slimguide calipers which are about $30.  I’ve had my set for over a decade now, they are indestructible and I’ve checked them against more expensive Lange calipers and they show extremely high accuracy.  In terms of cost:accuracy ratio, I think these are the best.

I’d note that, depending on the spring tension, all calipers can give slightly different measurements, although they are usually within a millimeter or two of one another.  As long as you are using the same calipers each time, this is irrelevant; you’ll still get consistent measurements.

In the hands of a trained operator, calipers are surprisingly accurate, giving values anywhere from 3-5% different from hydrostatic weighing.  In the hands of an untrained operator, they aren’t very accurate at all. There are a lot of untrained operators out there and this causes problems (it’s usually suggested that someone do at least 100 measurements to get even remotely skilled at the method).

Most health clubs and gyms, as well as a lots of other places, can do caliper measurements. Since caliper technique can vary quite a bit, it’s important to have the measurements done by the same person if at all possible. With the high turnover rate of employees at most commercial gyms, this can be tough to do.

For that reason alone, I usually recommend that people learn to do at least some of their own skin folds.  You won’t be able to reach all of them unless you’re a contortionist but the key skinfolds (usually abdominal and iliac crest for men and thigh for women) can be gotten to.

As a final comment, caliper equations can be problematic at best, for reasons I sort of glossed over above in the section on underwater weighing.  A lot of assumptions are being made about things like body density that aren’t turning out to be that correct and this can cause the equations to throw out some strange values.  It’s not unheard of for athletes to come up with negative body fat estimates; this is just a consequence of the equations being wrong for them (researchers are constantly developing new equations for this reason).

A current trend is to simply use the sum of skin folds and look at changes. If your skin folds are going down, you’re losing fat; if they’re going up, you’re gaining fat.  Depends on what the specific goals are, trying to put specific body fat numbers to that may or may not be valuable.

Bioelectrical Impedance Analysis (BIA)

BIA is another popular method for measuring body composition; much of this has to do with it being fairly easy to measure.  Unlike calipers, it doesn’t require training and since it’s high-tech (looking anyhow), people tend to put a lot of stock in the results.

Gyms will often use BIA methods, they can be found at all kinds of health fairs and, as I mentioned on Wednesday, there are now scales (such as the Tanita) that use BIA to give body fat estimates.  BIA is used in some research studies as well.  Basically, BIA is quick and easy.

But is it accurate?

Yes and no.  If strict hydration protocols are adhered to, BIA is actually reasonably accurate.  The problem I see is that, in the real world, these protocols aren’t followed and this will throw off the measurements completely.  To understand why, I should probably actually explain how BIA is done and what it’s measuring.

A typical BIA machine will have an operator attach one electrode to the back of your hand and one to your foot, there are also hand-held models where you just hold onto two handles, the scales obviously run through your feet.

Usually some data is entered such as age, height and weight (some will let you choose from athlete or non-athlete and give different results depending on which you pick) and then the machine runs a current from one electrode to the other (no, it doesn’t hurt).

BIA works by estimating total body water.   Now, water is conductive, that is electricity can move through it (if there are minerals present) and different tissues such as bone, muscle and fat all contain different amounts of water.

So by measuring how fast the current moves from one electrode to the other, BIA machines can estimate how much water is present in the body and use that to determine how much fat, muscle, etc. you have. Or at least that’s what it is trying to do.

And that brings in the problem I mentioned above: hydration state can throw off BIA tremendously.  Both dehydration (as might occur when carbohydrates are lowered) or hyper-hydration can throw off BIA completely.  Even a large urination or a big glass of water can throw off a BIA measurement by a few percentage points.

So unless you’re following those strict hydration protocols, BIA can be terribly misleading.  If you’re slightly differently hydrated from the last measurement you took, what looks like an actual change in body fat percentage may actually just be a difference in water balance.

Now, in BIA’s defense, assuming someone kept their hydration state constant (i.e. measuring themselves every Monday after urinating but before breakfast), BIA may give at least comparative measurements.  Just make sure you always measure under consistent conditions.

Infrared Reactance

While rarely seen anymore, IR had a brief stint in the sun, mostly at health fairs and some gyms. Originally developed to measure body composition in cattle, IR worked by bouncing a beam of infrared light off your upper arm bone and seeing how long it took to get back.

Since infrared light travels faster through muscle than fat, the machine could estimate how much fat you had. Since it only measured the biceps (upper arm), it was quick and easy. It was also pretty inaccurate. I can’t recall ever measuring anybody who had a lot of fat on their upper arm so that one measurement won’t tell you much about the rest of the body.

When measuring cattle to determine price at slaughter, a few percentage points aren’t that big a deal. For humans, I consider IR unusable and do not recommend it.

BodyMetrix 2000

In a related vein to Infrared Reactance, I should probably mention a new method of measuring body composition (someone asked about this in the comments section of Wednesday’s article) which is the BodyMetrix 2000.  Using ultrasound, the BodyMetrix claims to measure the thickness of fat, apparently using the same sites that are used for standard caliper measurements.

I’ll be 100% honest that I can’t say much about this; the entirety of my knowledge comes from what information they have on their site.  I’ve seen no validation data (they have a few PDF downloads on their site including ones showing good correlation with caliper data) and never seen nor used one.

The Bodymetrix device is far more expensive than calipers but if it avoids some of the inherent issues with caliper methods (operator accuracy, etc.) this might be a worthwhile tradeoff.  While it seems too expensive for home use, it wouldn’t surprise me if health clubs and such moved to this if it turns out to be accurate.

The Bod Pod

One of the recent high-tech developments in body composition methods is the Bod-Pod; essentially this is a dry version of hydrostatic weighing.  The Bod-Pod measures how much air you’re displacing, measures body mass and body volume and uses that to estimate body density and body fat percentage.

To be honest, I’ve never seen one of these in the real world and they are exceedingly expensive. The Bod-Pod site doesn’t even list prices and you know the rule…if you have to ask.

Anyhow, I’m not sure anybody would ever actually come across a Bod-Pod outside of an absurdly high-end health club or research center.  I mention it only for completeness.

Dual Energy X-Ray Absorbitometry (DEXA)

DEXA is another high-tech method that, recently, has become more prevalent and at least affordable.  DEXA basically does a full body scan from head to toe; it’s primary use has been to examine changes in body density.  But it also does a good job of measuring body composition since it’s able to differentiate between bone, muscle and fat tissue (because of how each absorbs the X-rays).

One neat aspect of DEXA in terms of body composition is that it will give you a measure of regional body composition (it will also measure visceral fat which none of the other methods can do).  That is, it will tell you if you carry more fat in the upper body, legs, arms, etc.  Then again, so will caliper or looking in the mirror and they are both a lot cheaper.

DEXA scans have come down in price considerably, however, and they might be useful to correlate a method such as calipers or the circumference equations.  That is, go drop the cash for a DEXA and either run a set of caliper measurements or one of the circumference equations and see how the simpler/cheaper/faster methods correlate in terms of accuracy.

It would be ideal to do a second set of each after some time on your diet simply to see if the simpler methods are also tracking changes with decent accuracy.  If so, you can just use the simpler methods from then on.

Non Body Composition Measurement Methods

Next let me look at non-body composition methods.  By this I mean that these methods do not actually measure body composition but can still provide useful information on whether or not what you’re doing with your eating and training program is working.

The Mirror/Pictures

Certainly the lowest tech method of seeing what’s going on with your body is the mirror; and while it doesn’t measure any aspect of body composition, that doesn’t make it useless.  At the very least, you can usually look in the mirror (naked, or semi-clothed, mind you) and get a rough idea if you’re underweight, overweight or just about right (whatever those terms might actually mean).

At the very least, you can determine if you’re happy with the way that you look. That is, if you can be honest with yourself.  This is not always a safe assumption.

The problem is that we tend to see what we want to see, good or bad.  Anorexics see a fat person where a skinny person is standing, and some bodybuilders see a skinny person where a muscular person is standing. Some researchers call this “reverse anorxia” or “bigorexia” (I find that last term really stupid for some reason).

Without getting into a huge tangent about how we perceive ‘reality’, the fact is that our brains lie to us sometimes and we don’t always see reality.  This makes the mirror useful but you have to be careful.

I should note that folks can often find magic mirrors; there seems to be one in every gym that makes people look drastically better than they actually do.  The lighting is just right, the mirror of whatever quality, that people see definition that doesn’t exist and that sort of thing.

If someone could figure out what physical characteristics make up these magic mirrors, they could make a million dollars selling it to dieters and bodybuilders alike.  For athletes in the physique sports, these magic mirrors can add up to a lot of disappointments on contest day.

Basically, the mirror, while good, is subject to normal human frailties in being honest with ourselves.  I’d rarely recommend it as the sole mode of tracking progress, there’s just too many possibilities for people to go screwy.  Use it but with caution.

In a semi-related vein, I should probably mention the use of photos to track progress in body composition.  Many coaches recommend taking pictures (front, back, side) to keep a visual comparison of progress over time.  Basically, you can put the pictures next to one another and see visual changes over time.

This actually avoids another huge problem inherent to the mirror: when you pose in front of them daily (admit it, you do), the small changes that may be occurring may not be visible.  In contrast, if you take pictures every 4 weeks, the changes should be large enough to show visually.

I’d note that it’s critical that, if you use the picture method, that you be consistent.  Take them in the same lighting, wearing the same clothes, with the camera the same distance from you every time.     If you don’t do this, it makes it much harder to tell if real changes are occurring.

Scale Weight

For years and years and years dieters focused primarily on changes in scale weight. If the scale went up, that was bad (unless weight gain was the goal); if it went down, that was good (assuming weight loss was the goal).  Of course, we know now that things are a lot more complicated than that and now we know to focus on body composition.

In pretty much all of my books, I go into a rather length discussion of body weight vs. body composition and weight vs. fat loss.  You can go read the article on the site if you’re still unclear but the short-version is that your total weight is made up of every part of you: fat, muscle, brain, organs, bone, fluid, undigested food in your gut, etc.

In general, when the goal is body re-composition, you’re looking to lose fat, gain muscle or some combination of the two.

When you just ‘lose weight’, you don’t know what you actually lost.  Was it fat, muscle, water, you had a huge bowel movement?  The standard bathroom scale can’t tell you.

I would note that, for people carrying a lot of fat, changes in scale weight will generally scale with changes in true fat (excepting the initial water weight loss, which can be considerable in large individuals).  That is, typically, of the total weight loss in a very fat individual, 90% or so will be fat.  So changes in scale weight are a fairly good indicator of changes in fat mass.

For leaner individuals, this stops being the case.  Muscle loss can make up 1/4-1/3rd of the total weight loss under some conditions, just looking at scale weight by itself doesn’t provide enough information; the scale MUST be used with another method to accurately track changes.

I should at least mention the supposed ‘body fat’ scales such as Tanita while I’m at it; there are expensive scales that are supposed to estimate true body fat percentage and body composition using a method called Bio-electrical Impedance Analysis (BIA); I’ll talk about them on Friday.

Body Mass Index (BMI)

The BMI is probably the current favorite method to measure ‘body composition’, especially in large groups.  The reason for this is that it’s easy, if you have height and weight, it’s a quick calculation to get BMI.  Essentially, BMI is like the old optimal height-weight charts that the insurance companies used back in the day but in nifty graphical form.

Now, in the average, non-athletic folks, BMI is actually a decent indicator of overall health with both high and very low BMI’s correlating with various health risks.  I’m not saying it’s perfect but it is decent.  Please read that sentence again in case you’re unclear on what I said.

As I mentioned above,  BMI can be used to get a rough indicator of body fat percentage (that is true body composition), I use this method in both The Rapid Fat Loss Handbook and A Guide to Flexible Dieting.  Again, I’m not saying it’s perfect or 100% accurate but it will get people within shooting distance.  For non-lean and untrained individuals, that’s usually good enough.

However, in athletic individuals (who tend to bitch about BMI a LOT on the Internet), BMI is basically useless and I want to explain why.  The basic problem is that, outside of the method in my books, BMI doesn’t actually distinguish between fat and muscle mass.  All it does is relate weight and height and higher numbers are bad (very low numbers are also bad).

But, this misses the whole point of body composition as a 200 pound individual at 10% body fat and a 200 pound individual at 30% body fat are clearly not identical.  The first is a lean athlete, the second is not.  And relative health risk will likely be very different.   But BMI will say that they are identical in terms of their relative health risk or what have you.

But this is pretty much a big part of why it works just fine for the non-training population: you simply don’t see individuals who aren’t training carrying a ton of muscle mass when their weight is high.   Not in general anyhow.  So, in that population, BMI will give a good indicator of how much fat someone is carrying and, by extension, relative health risk.  I hope that makes sense

Tangentially, I should note that some researchers feel that the BMI/height-weight charts are unrealistic for most people or provide unrealistic expectations (e.g. the average overweight individual won’t ever reach ‘normal’ BMI levels and the charts will have a negative impact).  Research has consistently shown that even a 10% reduction in body weight carries health benefits so even if overweight individuals can never reach a ‘normal’ BMI, that doesn’t mean all is lost.

In any case, back to BMI.  As noted above, in relatively inactive, non-training populations, BMI gives at least a rough indicator of health risk.   A BMI > 25 kg/m² is considered overweight, > 30 kg/m² is obese. Higher numbers correlate with more health risks. So do BMI’s that are excessively low (indicating severe underweight or eating disorders).

If you want to know your BMI, there’s a calculator here:

BMI Calculator

As mentioned, non-athletic folks can even use their BMI to get a rough estimate of body fat percentage (the conversion charts are in both books mentioned above).

Athletic folks shouldn’t even consider using BMI for any application.  Not to determine relatively health risk and not to estimate body fat percentage.  They must use another method.

The Waist/Hip Ratio (WHR)

While early research into health and body composition/body fat focused primarily on total body fat levels, it became clear fairly early that not all fat is the same in terms of the impact it has on overall health and health risks.

Simplistically, fat on the body can be divided into several different ‘types’.  I actually described five different types in The Stubborn Fat Solution but I’m only going to talk about two here: subcutaneous and visceral fat.

• Subcutaneous fat: This is the fat that you can see and most are worried about when they want to ‘lose fat’.  It’s found under the skin (‘sub’ = under; ‘cutaneous’ = skin) and comprises something like 40-60% of the total fat on your body.
• Visceral fat: This fat is found internally, surrounding the organs and such.

Now, as it turns out, carrying excessive amounts of visceral fat tends to correlate with various health risks including insulin resistance and Syndrome X (aka the metabolic syndrome).

It’s still being debated whether visceral fat is a cause or the result of Syndrome X.  But the bottom line is that carrying large amounts of visceral fat tends to be related to various health problems.  In contrast, having a lot of subcutaneous fat doesn’t carry nearly the same risk.

And that’s where the waist/hip ratio comes in; it’s a quick method to determine relative body fat distribution and therefore health risk.  It’s less about body composition and much more to do with overall health risk and fat patterning.

In common parlance, people are typically either pears (skinny upper body/fat lower body which means low visceral fat and high subcutaneous fat) or apples (round in the middle tapering at either end which usually means large amounts of visceral fat).

I’ve never quite figured out what people who carry their body fat very evenly are supposed to be called. A banana?

Generally speaking, women tend to be pears and men tend to be apples. However, extremely fat women will eventually start to accumulate visceral fat (and just become generally round) and post-menopausal women who don’t go on hormone replacement therapy typically show a shift from a pear to an apple shape.

And tying this in with my comments above, Individuals who are apples (having a high waist/hip ratio), because they are carrying more visceral fat, tend to have more health problems than those who are pears.

Excess body fat can always be a health risk but having an apple shape is worse than having a pear shape. For example, it’s thought that one reason women are protected from heart attacks/disease before menopause is because they store most of their fat in their lower bodies, instead of viscerally (around their gut and stomach).

Determining WHR is as easy as getting out the tape measure and throwing it around your waist and hips and comparing the two. Or just look down, if your stomach sticks out more than your hips, your WHR is probably too high.  If you want a more accurate method, you can use the calcuator at:

https://www.healthcalculators.org/calculators/waist_hip.asp

To get a true measure of the WHR.

Circumference Measurements

Another commonly used method of tracking changes in body composition is to measure circumferences, arms, waist, thighs, etc.  The method is simple and fast, just throw a tape measure around whatever you want to measure and see what the number is.

Now, there are methods of using circumference to truly estimate body fat percentage.  The various equations seem to range from reasonably accurate to horrible.  The main benefit, and this will make more sense after Part 2 on Friday is that it’s faster than other methods.

Groups like the military often use circumference methods since they can be done quickly on a large number of recruits.  I’ll discuss circumference methods for estimating body composition more in Part 2 on Friday.

Of more relevance to today’s article, circumference methods are primarily used to track progress on a diet or training program without being used to measure body composition specifically.

Folks trying to gain muscle mass (or improve a certain muscle group) will often use the tape measure to track changes; is the size of the muscle going up, down or not changing (when combined with caliper measures, discussed on Friday, this can be an extremely valuable method of tracking progress).

Dieters can use the method similarly; men may track waist circumference while females might track thigh circumference to see if the diet and training is working as it should. Whether it’s to track overall changes or simply trying to reach some specific goal (e.g. 32 inch waist), circumference measures indicate what’s going on.

I should note that, to be accurate at all, a tape measure has to be used correctly. One issue is that any measurement you make must be made at the same place every time.  Folks who do this for a living use very very specific methods of determining where to take measurements.  But even small differences in where you take the measurement can give different results.  It has to be consistent to be meaningful.

As well, it’s altogether too easy to pull the tape to a different tightness if you’re not careful.  Dieters will tend to pull the tape measure a little tighter to get a lower value and folks seeking muscle gain may let it run a little bit loose.  Some companies actually sell expensive little tape measures with built-in springs to ensure that the tension on the tape is identical every time.

Basically, circumference methods are good but only if you respect their limitations: you must measure at an identical place every time and you have to pull the tape to the same tension every time.  These can be difficult to achieve sometimes.  Unfortunately, it would take another article to address both in any useful detail.

The Guide to Body Composition continues in Body Composition – Measurement Problems

Similar Posts:

• Body Composition – Measurement Problems
• DEXA vs Calipers for Body Fat Estimation
• Body Composition – Recommendations
• Body Composition – Calculations
• Of BMI and Weighing Frequency