Does Body Composition Measure Up?Thursday, February 5, 2009
This week I am attending the 5th Asian-Oceanic Congress on Obesity hosted by the All India Association for Advancing Research in Obesity, in Mumbai. My first presentation at this meeting was during an Obesity Certificate Workshop for physicians and allied health on the assessment and management of obesity.
I was asked by the organizers to talk about the assessment of body composition and its role in clinical practice. As I pointed out to my audience, a wide range of methods have been developed and used in studies of body composition:
– Dilution techniques (40K)
– Under-water weighing
– Air displacement plethysmography
– Bioelectrical impedance analysis (BIA)
– Dual energy X-ray absorptiometry (DEXA)
– CT or MR imaging
– 3-D photonic scanning
– Quantitative magnetic resonance
Clinical use of all of these methods is limited by one or more factors including accuracy, reliability, size limitations and cost. As experts in this area are well aware, you could host whole symposia on discussions around the virtues and drawbacks of each of these methods. Techniques that are great for field studies in populations may be too inaccurate for clinical decision-making in individuals. Techniques that have high precision and reproducibility may be too expensive for routine clinical practice.
But the key question of course is, whether or not knowing the exact body composition of your patient will actually influence management. While there are many theoretical benefits to knowing the exact body composition of your patient and perhaps even monitoring their changes with weight loss, there is thus far no clear indication that management or outcome is indeed better when body composition measurements are added to simple measures of weight (and waist circumference?).
There are of course situations where changes in weight alone are difficult to interpret:
– Rapid or extreme weight loss
– Protein malnutrition
– Certain medications
As with any test, clinicians should order tests with a clear expectation of how results will influence management and lead to better patient care. Just because a test is simple (or sexy) and/or widely available does not necessarily mean that it should be used in routine practice.
At this time, measures of body composition in clinical practice are probably best reserved for situations where this information is likely to assist in meaningful decision making.
Obviously, this take on body composition resulted in an extensive and heated discussion, illustrating not only that this is a topic of great interest to practitioners but also that views on how the value of such measurements are perceived varies from indispensable to useless.
What do my readers think? Who routinely measures body composition and how is this helpful?
Saturday, February 7, 2009
I use a hand held BF analyzer to monitor fat loss vs LBM loss . The day to day fluctuations are irrelevant, but month over month, the trend is what is important. I don’t think it matters which method is used as they all capture a single point in time and it’s the trend of the change that matters.
Sunday, February 8, 2009
Arya, great post, and i would have loved to hear the talk. When you and I worked at HGH, we used the Tanita BIA religiously. But it soon became apparent that it was resulting in some problems – patients weight would change and their BF wouldn’t or the other way around, they would stay the same weight and have a change in BF. Since we were weighing them weekly, this fluctuation in BF clearly demonstrated the large variance and margin of error with most BIA. Since all of my 3000 pts at the Wharton Medical Clinc are weighed weekly, we have had to eliminate the Tanita, as it was too challenging to explain the variation in BF. Patients put a lot of energy and emotion into each pound lost or gained and each BF% lost or gained, so margins of errors are not well tolerated. We now use fat calipers or the BIA for the 1st visit measurement and then again not again until 10% weight loss. Note: BF has no impact on our treatment options or the patients success. It does help me to explain sarcopenia to them, but i can do this without the BF%. We would like to move to DEXA eventually for research purposes only.
Monday, February 9, 2009
Hi — i find this argument very interesting and I agree with Sean. I try to focus on loosing body fat and not so much the scale in the office (though am weighing patients), only because I find when they start adding muscle mass, if they are weighing themselves at home, they get so discouraged. Because many of them have mood disorders anyway, it is hard to motivate them and they get so discouraged with the scale, despite the good work they maybe doing to change their lifestyle. I was planning to do fat calipers as issues with purchasing equipment that may not be validated for general use/affect management, is not a priority in my current clinic. i would be interested in where this conversation goes, if at the end of day, it does not change management. I do think focusing on BF helps with translating knowledge on weight loss- amongst clinicians and patients.
Sunday, February 15, 2009
This is so interesting. We all agree on the limitations of BMI, even though most of us (including me) continue to make major decisions based on BMIs. At least 2 commonly-encountered subsets of patients will benefit from a body composition analysis. One subset is those who are obese, and are also performing athletic activities (eg, football players, wrestlers) who wonder if their body mass is mostly muscle. The other is those who are actively pursuing weight loss, who faithfully exercise, and do not lose as much weight, and wonder whether the reason is an increase in the muscle mass. Great post!