Body Composition

I’ll let you in on a little secret – the scale lies.  Well, it doesn’t actually lie but it doesn’t tell the whole truth, which is kind of the same thing, isn’t it? Body weight and Body Mass Index (BMI) can be valuable tools, but these numbers yield only a very small piece of the picture.  Body Composition, on the other hand, sheds light on how those pounds on the scale are distributed, giving  a much closer estimate of the whole  truth.   The term body composition refers to how much of your body weight is fat, how much is tissue and how much is fluid.  There are a number of different methods for calculating body composition including hydrostatic testing, bio-impedance analysis, radiographic body density assessment and skin fold measurements.  At Hygeia, we perform bio-impedance analysis (BIA) on all of our new patients, and annually on patients presenting for routine health maintenance visits. 
In the two-compartment model, the body is broken down into two categories: Fat Mass and Fat-Free Mass.  Through BIA both the subcutaneous and visceral fat tissue is measured.  Visceral fat, the fat that surrounds the organs in our abdomens, is metabolically active and when elevated can contribute to a number of poor health outcomes including hypertension, elevated cholesterol, Type II diabetes and cardiovascular disease.  In addition to avoiding excessive fat mass gain, maintenance of our lean body mass, in particular our muscle mass, is a critical component of healthy aging. 
Through bio-impedance assessment, the body composition can be broken down further into what is referred to as the Five Compartment Model (see below).  This allows for a more detailed analysis of the fat free mass, breaking this compartment into fluid and tissue.  The determination of Body Cell Mass (BCM) allows for an approximation of the muscle mass.  Although this compartment also includes the internal organs, our organs don’t typically vary in weight over time.  Therefore gains or losses in the BCM are reflective of changes in muscle mass.  The assessment of fluid status also provides information about the health of the cell membranes.  The fluid within our cells tends to decrease as we age and the BIA helps to identify situations in which cells are prematurely losing the capacity to maintain hydration.   
While the body composition information is wonderful to have, even better is the ability to modify our body composition through our lifestyle choices.  When we first obtained our BIA device I tested myself frequently as I was learning to use the technology and interpret the results.  I was surprised to find that while I maintained a very stable weight over the course of the year, my body fat varied significantly with the seasons.  In the summer when I was physically active and eating a large number of fresh fruits and vegetables, my body fat was quite low – in the optimal range for fitness I am proud to say!  However, in the winter, when I stopped running and cycling and turned to high carbohydrate comfort foods to sustain me during the long, dark days, I lost quite a bit of muscle and gained an equal weight of fat mass.  Thus, the numbers on the scale didn’t change, but I sure did! 
Body composition assessment has also proven to be very useful for a number of my patients who are embarking on aggressive weight loss programs.  (I encourage my patients to consider these body composition programs for reasons which will soon become clear).   I have seen patients come in very excited about a substantial weight loss only to find that they have gained fat mass and lost water and muscle.  In these patients we make adjustments to protein consumption and exercise to help restore muscle mass and encourage fat mass loss.  On the other hand, some patients come in frustrated with the scales refusal to budge after months of dedicated exercise and dietary change.  Often, these patients are thrilled to see a dramatic drop in fat mass -- the simultaneous rise in muscle mass confuses the message from the scale. 
So what can you do to optimize your body composition, lower your risk of metabolic diseases and enhance your vitality?  Just think in terms of compartments.  In order to lose fat mass you need to burn calories – consistent exercise and intermittent fasting can be very effective for fat mass loss.  While there are genetic differences which can impact what type of exercise is best for any given individual with respect to fat loss, a general rule of thumb is 30 minutes of moderate aerobic exercise most days of the week.  In addition to losing fat mass, it is also important to focus on maintaining or increasing lean body mass.  Lean body mass is supported by assuring consumption of adequate dietary lean protein (also assuring that you are able to digest and absorb this protein efficiently).  Resistance exercise with weights, balls, or bands will help to maintain lean body mass if practiced 2-3 times weekly, and can help to increase lean body mass if practiced 4-5 times weekly.  Finally, stress management is key to supporting our lean body mass.  High levels of stress hormones not only interfere with our ability to digest and absorb our proteins but also encourage our bodies to burn muscle for energy. 
The next time you think about stepping on the scale, take a moment to think about all of the information you aren’t getting.  I don’t have a strong agenda about using or not using bathroom scales.  I personally step on mine every morning.  I use this information to get a rough estimate of my hydration status and to make changes to my routine if persistent patterns of loss or gain are appreciated.  However, I don’t let the scale judge me and I am fully cognizant of its limitations.  If I’ve been eating well and exercising consistently I assume a few extra pounds are related to muscle gain.  If the way my clothing fits suggests otherwise, you’ll see me checking my body composition before modifying my regimen!

The 5 Compartment Model of Body Composition.
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