I really liked this approach of determining the underlying reasons for why we got fat. I suspect most of us will have multiple reasons and do a “1 from column A, 2 from column B” type of approach, but it helped me think through what underlying behaviors need to be be addressed for different people.
Synopsized from Dr. Sharma’s Obesity blog post, Are There Merits To Subtyping Obesity?
Regular readers may recall that several years ago we proposed that it was time to move beyond considering obesity a homogeneous entity (as defined by BMI alone) and suggested that clinicians may be better off using an “etiological framework” for assessing and addressing the diversity of factors that drive weight gain.
This notion, that obesity is not a homogeneous condition, is something other researchers are now slowly catching up with.
One example of how “mainstream” thinking is gradually embracing the concept of heterogeneity in obesity is a recent paper by Allison Field and colleagues from Harvard Medical School published in JAMA.
In this paper the authors state that,
“One reason for the lack of stronger associations with risk factors or more consistently successful treatment is that all types of overweight and obesity are often grouped together. This approach potentially obscures strong associations between risk factors and specific subtypes of obesity.”
While the the etiology of obesity applies to the many drivers of obesity (which we have categorized as predominantly affecting metabolism, ingestive behaviour and/or physical activity), the phenotype of obesity applies to the many consequences of obesity (which we have categorized as affecting physical, mental and functional health). As we have previously pointed out, the two are not necessarily related.
Thus, two individuals, gaining weight for entirely different reasons (e.g. food insecurity vs. binge-eating syndrome), may well present with exactly the same amount of excess body fat and identical clinical complications (e.g. diabetes, reflux disease and urinary incontinence).
On the other hand, two individuals, gaining weight for exactly the same reason (e.g. on anti-psychotic medications), may present with quite different complications (e.g. sleep apnea vs. osteoarthritis).
The authors are certainly correct in their statement that,
“Obesity is a heterogeneous and complex disease influenced by exogenous and endogenous exposures. Stratifying obesity into meaningful subtypes could provide a better understanding its causes and enable the design and delivery of more effective prevention and treatment interventions.”