A recent American study suggests more than 50% of people with a normal BMI meet the Lancet Diabetes & Endocrinology Commission’s criteria for clinical obesity.
How common is clinical obesity, really?
Last year the world was introduced to the concept of “clinical obesity”, a diagnosis resulting from an individual having excess adipose tissue based on an anthropometric measure (such as waist circumference, waist-to-hip ratio, or weight-to-height ratio) as well as evidence of organ or physical dysfunction (e.g., left ventricular systolic function, raised arterial blood pressure, or signs of raised intracranial pressure).
The concept, developed by the Lancet Diabetes & Endocrinology Commission, came from the view that using BMI alone to define obesity does not indicate the presence of organ or physical dysfunction due to excess adiposity.
Since the release of this definition, the national prevalence of clinical obesity in the United States has been estimated to be somewhere between 10% and 40%, but these estimates have not considered how the rate of clinical obesity differs by BMI class.
“National estimates by BMI class can help distinguish how a diagnosis of clinical obesity would differ from BMI-based obesity and illustrate the distribution of clinical obesity across the general population to inform generalizable clinical practice,” write the authors of a new research letter published in the Annals of Internal Medicine.
To provide such estimates, the researchers used data from the 2021-2023 cycle of the National Health and Nutrition Examination Survey.
Specifically, they classified 5642 non-pregnant adult patients (average weighted age 48.7 years) based on their BMI class, excess adiposity status, and clinical obesity status before using the data from this cohort to calculate survey-weighted prevalence rates.
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The overall prevalence of clinical obesity in the survey-weighted sample was 53.8% (95% confidence interval 51.4-56.2%). As expected, the prevalence increased with BMI category: 2.7% (0.0-7.2%) for underweight individuals, 26.1% (22.8-29.4%) for people in the normal BMI category, 50.3% (46.5-54.0%) for overweight, 65.6% (61.1-70.1%) for obesity I, 77.8% (73.2-82.4%) for obesity II, and 85.3% (82.6-88.0%) for obesity III.
“These finding suggest that incorporating multiple anthropometric indicators may detect persons with physiologic consequences of excess adiposity who would otherwise be missed using BMI alone; this should be assessed in prospective studies for causality and to determine how adiposity influences various organ dysfunction outcomes,” the researchers wrote.
“Given that current clinical guidelines for screening of obesity-related medical conditions and thresholds for treatment (for example, with incretins) are based on BMI, these findings, if adopted, have important implications for screening and clinical interventions.”
The study was limited by the fact that the NHANES does not capture the full range of clinical data required for researchers to fully explore the impact of the Commission’s proposal, meaning the true prevalence of clinical obesity in the current sample was likely underestimated.
