To the Editor
In the Original Investigation by Nyberg and colleagues1 regarding healthy lifestyles and years lived without chronic disease, the finding that a body mass index (BMI) less than or equal to 25, in combination with healthy lifestyle factors, predicts more life-years without chronic disease is noteworthy and important. However, the characterization of a BMI lower than 25 as a healthy lifestyle itself is misleading and conveys implicit bias about the nature of BMI and obesity.
Obesity is a complex, chronic, multifactorial disease in which lifestyle plays a role, along with an altered food supply, the built physical environment, genetic susceptibility, epigenetics, and a host of other factors.2 As reported by Kyle et al,3 the American Medical Association joined numerous other medical organizations in recognizing the nature of obesity as a disease in 2013.
Obesity itself is defined by excess adiposity that harms health. Body mass index is a useful measure for estimating the prevalence of obesity in a population. A BMI greater than or equal to 25 defines overweight in the population, and a BMI greater than or equal to 30 suggests a diagnosis of obesity. However, at an individual level, a more complete assessment of body composition and clinical status is necessary for diagnosis.
In 2018, Gordon-Larsen and Heymsfield4 outlined the problems with misclassifying obesity as a lifestyle behavior. Treating BMI as a lifestyle behavior obscures the complex etiologies that contribute to BMI and the metabolic disease of obesity. Perhaps more importantly, it promotes a mistaken notion that is the foundation for weight bias and stigma–that obesity is a condition that patients choose for themselves through behaviors they elect. The resulting weight bias is well-documented to harm both health and quality of life for people living with obesity.5 In addition, it can promote the progression of obesity and discourage patients from seeking appropriate medical care.
For all these reasons, it is essential to recognize that BMI is a physical characteristic and a marker for metabolic disease. Body mass index itself is neither a behavior nor a life-style, even though health behaviors and lifestyle factors can influence BMI. Many other factors are contributors. Medical professionals must recognize this fact to provide adequate care for patients with obesity.
Funding/Support:
This work is supported by the following sources of funding: National Institutes of Health and Massachusetts General Hospital Executive Committee on Research (Dr Stanford), National Institutes of Health NIDDK P30 DK040561 (Dr Stanford) and L30 DK118710 (Dr Stanford).
Role of the Funder/Sponsor:
The National Institutes of Health and Massachusetts General Hospital Executive Committee on Research had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Footnotes
Conflict of Interest Disclosures: Dr Kyle reported personal fees from Tivity Health, Novo Nordisk, and Gelesis. Dr Nadglowski reported grants from Obesity Action Coalition during the conduct of the study. Dr Stanford reported grants from the National Institutes of Health. No other disclosures were reported.
Contributor Information
Theodore K. Kyle, ConscienHealth, Pittsburgh, Pennsylvania.
Joseph F. Nadglowski, Obesity Action Coalition, Tampa, Florida.
Fatima Cody Stanford, Massachusetts General Hospital, Boston; Harvard Medical School, Boston, Massachusetts.
References
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