DEXA scan is known as the most accurate method of body composition testing, DEXA can help measure body fat as well as muscle mass and bone density

DEXA Scan: How Cenegenics Accurately Measures Body Composition

With roughly 50% of U.S. adults actively trying to lose weight [1] and more than 70% considered overweight or obese, [2] its no surprise that everywhere we look we’re inundated with weight loss solutions. From supplements to diet and exercise programs, there are countless options designed specifically to elicit weight loss, many of which promise quick results. The industry for diet products and plans is valued at a staggering $70.3 billion, [3] while the $30 billion fitness industry has shown 3-4% annual growth for the last ten years. [4]

Indeed, being overweight continues to be an epidemic that demands attention from the population, intervention from health care providers, and practical approaches to manage a healthier lifestyle. Yet, there are inherent flaws with the way it’s currently being approached. Aside from the unrealistic promises made by many of these weight loss “solutions,” another issue surrounding weight loss is the fact that the vast majority of individuals pursuing loss of body fat are dictating their efforts based solely on one narrow measure: body weight.

What’s the problem with focusing on the number on the scale? After all, isn’t it called weight loss? Here, we debunk the weight loss myth and unveil the real measures of health, which can be used as guiding points to help you create a fuller picture of your wellness. We’ll also cover the powerful solutions for measuring these values and how having this knowledge can set the foundation for a more comprehensive approach to achieving and maintaining a healthy body composition.

Weight: Only One Piece of the Puzzle


In their quest to reduce body fat, most people use the scale as the guiding factor to determine their starting point and progress. They may also use weight as the basis for framing their goals; often we hear people struggling in their quest to lose “the last ten pounds.”

Yet, weight alone doesn’t provide a good marker for overall health. In fact, it’s just an arbitrary number used to measure the body’s relative mass. It’s the composition of that mass that matters, including how much of the body is made up of fat mass, lean mass, organs, bones, and other tissues. For this reason, evaluating weight alone can be very misleading.

For instance, an individual may actually weigh a lot but have little fat mass and a lot of muscle mass. While they would appear and feel healthy, by clinical standards, they could be deemed overweight. Often, this calculation is represented by Body Mass Index (BMI), which brings us to our next point.

The Shortcomings of Body Mass Index (BMI)


BMI is a calculation of a person’s weight relative to their height and is used to categorize individuals into groups such as healthy, overweight, obese, and morbidly obese. It’s a straightforward and free way to calculate body mass and can be routinely measured with reasonable accuracy. Below are two methods for calculating your BMI:

BMI Calculation 1:

Weight (lbs)

               --------------------  x 703     

Height (in)2

BMI Calculation 2:

Weight (kg)

-------------------------------

Height (m) x Height (m)

Classification of BMI is as follows:

  • Underweight: <18.5
  • Normal: 18.5 – 24.9
  • Overweight: 25.0 – 29.9
  • Obese: 30.0-34.9
  • Extremely Obese: >35
BMI is not the most accurate method of body composition testing, BMI can often be unresponsive or inaccurate especially in individuals with a fair amount of muscle mass


BMI has been used for decades and, in fact, was developed by a mathematician in the early 19th century. Yet, therein lies one of the first issues with the metric: it was not created by a physician and, moreover, the creator himself explicitly said that it should not be used to indicate the level of body fat in an individual.

Rather, the formula was developed to provide a quick overview of obesity among the general population to aid in government resource allocation. In other words, this flawed measure has been used to do the exact thing it was intended not to do for more than 200 years. [5]

Even the CDC has issued BMI considerations for practitioners, stating, “It is a surrogate measure of body fat because it measures excess weight rather than excess fat.” [6] While perhaps a useful tool for doctors and physicians who do not have other means of measuring body fat readily available, BMI doesn’t show the whole picture. And, to perform a comprehensive assessment of an individual’s health, you will ultimately need to see that whole picture.

BMI – Not the Whole Picture

Specifically, BMI falls short when it comes to addressing key values, such as body fat percentage (BF%), lean body mass, and fat mass. Body fat percentage is a representation of the percentage of the body that is made up of fat mass and is a better indicator of health status than overall weight.

Unfortunately, BMI is simply too narrow a measurement to determine body fat percentage. One of its key flaws is the fact that BMI doesn’t discriminate between types of fat. For example, a person with a high BMI carrying a fair amount of subcutaneous fat in the hips and buttocks won’t face the same risk factors as an individual with the same BMI, but who stores most fat in the abdominal region.

Visceral fat, or that which is located deep in the abdominal cavity, is inflammatory, and can release compounds that trigger disease. Contrast this with subcutaneous fat, or the pinchable type located just beneath the skin: this kind isn’t linked as readily to serious disease. [7]

Unresponsive or Inaccurate – Limitations of BMI

Moreover, there are certain instances in which BMI simply gets it wrong. As mentioned above, it fails to account for muscle. Lean body builders may weigh more for their height than what BMI standards would consider healthy, but these individuals do not have an unhealthy body fat composition and are likely not at an increased risk for disease based on body fat.

On the flip side, BMI can also overlook what’s considered “normal weight obesity.” People who are considered to be at a normal weight for their height may still carry excess body fat and, while they may appear thin, their excess fat could still make them vulnerable to issues like type 2 diabetes and heart disease. [8]

Finally, a frustrating scenario many individuals run into is finding BMI to be unresponsive. Through diet and exercise, people seeking to lose weight may find that the scale won’t budge. They may have successfully reduced their body fat percentage and increased lean muscle mass, but BMI calculations won’t reflect that.

This will lead people to perceive failures or stalled progress when in reality they have indeed made strides towards bettering their health; increased physical activity is linked to reductions in heart disease and mortality related to the condition, regardless of an individual’s size. [9] Yet, a reduction in body fat and gain in muscle mass can cause the net change in gross weight to stay the same, even while the body composition is much healthier.

Clearly, BMI has some major shortcomings and is by no means the most effective way to measure body fat. If that’s the case, however, the question still remains: what is the best way to determine body composition?

Methods for Testing Body Composition


There are currently a variety of methods available for testing body composition. The most common methods include the use of skin calipers, hydrostatic weighing, bioelectrical impedance, and finally, dual energy X-ray absorptiometry (DEXA). We’ll go through each of these briefly, with a greater focus on DEXA, as it is considered the gold standard for body composition analysis.

Skinfold Calipers

Skinfold calipers is often the most inexpensive method of body composition testing, The caliper technique is often less accurate as it leaves a lot of room for human error and variability

Skinfold calipers are easily accessible and inexpensive, which is why they are among the most common methods used to measure subcutaneous fat. The process involves pulling out a fold of skin from either three or seven parts of the body, such as the back of the arm, front of the arm, or the shoulder blade, and placing the skin between the calipers. The measures should then be added up and can be entered into an equation to provide a body fat percentage reading.

The benefits of this method are that they don’t require a lot of space and can be used by anyone. Yet, this method does leave room for human error and variability. One person may not use the calipers the same way as the next. Caliper technique, precise measurement location, and accuracy of estimations are all factors which can diminish the reliability of this method.

Hydrostatic Weighing

Once considered the gold standard of body composition measurement, hydrostatic weighing is rarely used nowadays. Also referred to as underwater weighing, this method is based on the Archimedes principle which states that upward buoyant force exerted on a body immersed in a liquid is equal to the weight of the fluid that the body displaces.

Muscle and bone are denser than water, but fat floats. Thus, a person with a larger percentage of free fat mass will weigh more in the water and have a lower body fat percentage. Conversely, a large amount of fat mass will make the body lighter in water. [10]

When performed properly, hydrostatic weighing is considered accurate and only has a +/- 1.5% error margin. Nonetheless, one potential barrier to achieving accurate results is the fact that the test relies on the patient’s ability to blow the air out of their lungs completely, both prior to the test and during it, using a spirometer. If the air is not completely expelled, it could create a miscalculation of body fat percentage, since air makes the body float. [11]

While this method was once hailed for its accuracy, it also presents some additional inherent issues. For one, it’s time-consuming, complex, and requires a significant amount of equipment and space. In-depth knowledge is also required to administer the tests and accurately calculate body fat. Moreover, it can also present challenges for the test subject as some people may find it difficult or unsettling to stay under water for the duration of the test.

Bioelectrical Impedance Analysis

Bioelectrical impedance analysis (BIA) is another method used to assess body composition. Modern BIA devices are noninvasive and have become more readily available and affordable. These solutions can be used to calculate body fat percentage, lean body mass, and overall mass.

BIA devices require the subject to place two electrodes on their right hand and/or foot. A low level current, undetectable to the subject, is sent through the body. The flow of this current is influenced by the amount of water inside the body and can measure how the signal is impeded by different types of tissue.

Blood, for example, is characterized by high amounts of electrolytes and fluid and therefore has high conductivity. Likewise, lean tissue, including muscle mass, is composed of roughly 70% water. Fat and bone, on the other hand, will slow the current. By determining the resistance of this flow, it can form estimates of body water to calculate body fat using specific formulas.

Factors That May Skew BIA Results

BIA can often be less effective than DEXA due to various models that can yield different full body measurements based on hand or foot placement, BIA can also be inaccurate if a subject is dehydrated which can reduce conduction rate

Variations of BIA devices may be used differently. Some models require hand to hand, foot to foot, or foot to hand placement. The units that encompass a full body measurement may yield the most accurate value, while hand to hand units may not produce enough current through the lower body. Conversely, the foot to foot systems may not obtain an accurate picture of body composition in the torso and arms.

While BIA is generally considered to be a feasible tool for accurately measuring body composition, there are a few additional factors that can lead to skewed results. One major influencer is the test subject’s level of hydration. As mentioned above, body water plays an essential role in the conduction of the electrical current.

Thus, the more hydrated an individual is, the faster the current will travel, leading to more accurate results. On the other hand, if the subject is dehydrated, the results may not be accurate due to the slower conduction rate. Therefore, to yield accurate results, it’s important that test administrators ensure the subject has consumed ample fluids beforehand.

DEXA Scan: Gold Standard of Body Composition Testing


Finally, we have the DEXA, the gold standard in body composition analysis. Coincidentally, it was originally developed to analyze bone mineral density, but medical professionals soon caught on to its powerful ability to be used as a body composition analysis tool. Like the aforementioned approaches, DEXA is a noninvasive test. It involves the use of two X-ray beams sent through the body at different energy levels.

DEXA is noninvasive and uses X-ray beams being sent through the body at different energy levels

It can measure changes in bone density as small as one percent and is therefore extremely sensitive and accurate. [12] This helps to determine risk and progression of osteoporosis, which is important for at-risk populations such as elderly individuals. The DEXA has the ability to scan specific areas in the body as well as the whole body. Perhaps the two most critical areas to assess for bone mineral density are the lumbar spine and the femoral neck (hips).

DEXA can help assess bone mineral density in the lumbar spine which can give physicians a better idea of your risk of fractures and falls

As we age, not only does our bone mineral density decrease, but we may lose balance and are at a much greater risk for falls. With that increased risk, we also are more likely to sustain fractures.

A hip fracture can double the risk of dying within a year in the elderly population, DEXA is an essential part of the Cenegenics Elite Health evaluation to help assess risk of fracture and  bone density

A hip fracture can double the risk of dying within a year in elderly populations. [13] The lumbar spine and femoral neck tests are ideal for determining bone mineral density and assessing fracture risks. For this reason, these tests are an essential part of the Cenegenics Elite Health assessment.

A DEXA scan can help determine a reliable baseline on which we can help set realistic goals to help move you toward optimal health

Yet, beyond the ability to accurately measure bone density, the DEXA is the most powerful means of providing data for body composition available today. Unlike the BIA which can be manipulated by water intake or the skinfold calipers which can be altered by the user’s technique, the DEXA is nearly impossible to fool.

Looking Beyond Bone Density

Not only does DEXA tell you the accurate composition of body fat and lean mass, but it also determines how it is distributed across the body. It is the only method that can reveal the precise amount of dangerous fat located around your vital organs which puts you at risk for serious disease.

The DEXA can even provide segmented data to indicate the amounts of lean mass on the arms, trunk, and legs on either side. This is beneficial for helping us understand the distribution of fat mass, as well as the specific diseases for which we may be at risk.

DEXA provides two fat distribution measurements: android and gynoid fat. While android is commonly seen in men and stored around the trunk and upper body (commonly associated with the infamous “beer belly”), gynoid fat is often seen in women and is stored in the lower body, including the hips and thighs. Android fat is commonly associated with hypertension, insulin resistance, type 2 diabetes, and heart disease.

DEXA Measurements Quick Navigation

The DEXA Scan measures

  • AP Spine Bone Density Trend
  • Densitometry Reference
  • Total Body Bone Density Trend
  • Total Body Tissue Quantitation
  • Fat Mass Ratio
  • Total Body Fat Percentage
  • DualFemur Bone Density Trend

The ability to tap into this previously inaccessible data on body composition does much more than uncover disease risk, however. More importantly, it gives us a reliable baseline on which we can set realistic goals to make specific improvements towards optimal health. For example, visceral fat responds best to certain exercises, including high-intensity interval training, while subcutaneous fat may be best approached using other methods. [14] Without an accurate understanding of which type impacts you, however, you’ll be missing a key piece of the puzzle needed to create sustainable improvements to your health. 

Premier Standard of Body Composition Measurement – In Conclusion


As the leader in age management medicine, Cenegenics provides its patients with the resources, tools, and services needed to take an all-encompassing yet targeted approach to improving their health and quality of life. Our clinical team leverages modern technology like the DEXA scan to uncover key indicators of health, which are then used to provide an individualized framework for treatment.

While benefits like improved body composition are a natural byproduct of these efforts, the more important achievements made include better overall health and longevity, and decreased disease risk.

If you’re interested in having your body composition assessed using the DEXA scan, contact Cenegenics today to schedule an assessment and go over your results with a physician.

Next Steps in Scheduling Your DEXA Scan

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Key Resources

This guide was produced with contributions from the following key resources: 

The Cenegenics Education and Research Foundation  

The Textbook of Age Management Medicine Volume 1: Mastering Healthy Aging Nutrition, Exercise and Hormone Replacement Therapy

Click to purchase

The Cenegenics Education and Research Foundation  

The Textbook of Age Management Medicine Volume 2: Mastering Healthy Aging Nutrition, Exercise and Hormone Replacement Therapy

Click to purchase

Textbook Authors:

Jeffrey Park Leake, M.D., CPT

Dr. Jeffrey Park Leake is a Partner and Director of Education at Cenegenics Elite Health specializing in age management and wellness. Having trained hundreds of physicians worldwide, Dr. Leake is also the Director of Education for the Clinical Strategies for Healthy Aging course at AMM Educational Foundation.

Todd David Greenberg, M.D., CSCS

Dr. Todd Greenberg is a practicing physician with a broad range of expertise, including wellness, exercise, sports injuries, and MRI of sports injuries. He is a Radiology Clinical Associate Professor at the University of Washington.

References

[1] Ducharme, Jamie. “About Half of Americans Say They’re Trying to Lose Weight.” Time. 12 Jul. 2018. Retrieved from URL: http://time.com/5334532/weight-loss-americans/

[2] “Obesity and Overweight.” Centers for Disease Control and Prevention. 3 May 2017. Retrieved from URL: https://www.cdc.gov/nchs/fastats/obesity-overweight.htm

[3] Roepe, Lisa Rabasca. “The Diet Industry.” BusinessResearcher. 05 March 2018. Retrieved from URL: http://businessresearcher.sagepub.com/sbr-1946-105904-2881576/20180305/the-diet-industry

[4] Midgley, Ben. “The Six Reasons the Fitness Industry is Booming.” Forbes. 26 Sept. 2018. Retrieved from URL: https://www.forbes.com/sites/benmidgley/2018/09/26/the-six-reasons-the-fitness-industry-is-booming/#10d88ca0506d

[5] Devlin, Keith. “Top 10 Reasons Why the BMI Is Bogus.” 4 Jul. 2009. NPR. Retrieved from URL: https://www.npr.org/templates/story/story.php?storyId=106268439

[6] “Body Mass Index: Considerations for Practitioners.” Department of Health and Human Services Centers for Disease Control and Prevention. Retrieved from URL: https://www.cdc.gov/obesity/downloads/bmiforpactitioners.pdf

[7] Cespedes, Andrea. “Problems With BMI.” Livestrong. Retrieved from URL: https://www.livestrong.com/article/93472-problems-bmi/

[8] Cespedes, Andrea. See above.

[9] Janiszewski, Peter M., PhD., and Ross, Robert, PhD. “Effects of Weight Loss Among Metabolically Healthy Obese Men and Women. Diabetes Care. Sept. 2010. Retrieved from URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2928342/

[10] “Body Composition.” Georgia State University Department of Kinesiology and Health. Retrieved from URL: http://www2.gsu.edu/~wwwfit/bodycomp.html

[11] Georgia State University, see above.

[12] Eustice, Carol. “What Is a DEXA Scan?” Very Well Health. 26 Nov. 2018. Retrieved from URL: https://www.verywellhealth.com/what-is-a-dexa-scan-190167

[13] “Elderly Women Who Break a Hip at Increased Risk of Dying Within a Year.” Kaiser Permanente. 26 Sept. 2011. Retrieved from URL : https://share.kaiserpermanente.org/article/elderly-women-who-break-a-hip-at-increased-risk-of-dying-within-a-year/

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