Biomarkers
Specific biomarkers are closely related to obesity. Leptin and resistin protein levels increase with adipose mass, while adiponectin decreases, probably contributing to insulin resistance. The higher levels of tumor necrosis factor–alpha and interleukin-6 from obesity contribute to chronic inflammation. The combined effect of chronic inflammation and insulin resistance allows greater bioavailability of insulinlike growth factor-1 (IGF-1), which has a role in initiating type 2 diabetes, cardiovascular disease, and cancer. Ideally, measuring these biomarkers could provide more advantageous information than BMI. Unfortunately, for now, the lack of standardized assays and imperfect knowledge of exactly how these biomarkers elicit disease prevents clinical use.
Obesity is a common, highly complex, chronic, and relapsing disease. Thankfully, a number of effective treatments and interventions are available. Although an accurate diagnosis of obesity is essential, underdiagnosed cases and missed opportunities for metabolic disease risk reduction persist. Overdiagnosing obesity, however, has the potential to incur unnecessary health care costs and result in weight bias and stigma.
While BMI is a quick and inexpensive means to assess obesity, by itself it lacks the necessary components for an accurate diagnosis. Particularly for individuals with a normal BMI or less severe overweight/obesity (BMI 27-34.9), other factors must be accounted for, including age, gender, and race. At a minimum, waist circumference should be measured to best risk-stratify and determine treatment intensity. Body composition analysis with BMI calculation refines the diagnosis of obesity.
Finally, clinicians may find best practices by using BMI delta change models. As with so many other clinical measurements, the trajectory tells the most astute story. For example, a patient whose BMI decreased from 45 to 35 may warrant less intensive treatment than a patient whose BMI increased from 26 to 31. Any change in BMI warrants clinical attention. A rapidly or consistently increasing BMI, even within normal range, should prompt clinicians to assess other factors related to obesity and metabolic disease risk (for example, lifestyle factors, waist circumference, blood pressure, cholesterol, diabetes screening) and initiate a conversation about weight management. Similarly, a consistently or rapidly decreasing BMI – even in elevated ranges and particularly with unintentional weight loss – should prompt evaluation.
Although BMI continues to be useful in clinical practice, epidemiology, and research, it should be used in combination with other clinical factors to provide the utmost quality of care.
Dr. Bartfield is assistant professor, obesity medicine specialist, Wake Forest Baptists Medical Center/Atrium Health Weight Management Center, Greensboro, N.C. She has disclosed no relevant financial relationships.
A version of this article appeared on Medscape.com.