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?