A recently introduced definition of obesity stands to dramatically expand the number of Americans diagnosed with this condition. Investigators from Mass General Brigham report that implementing the revised standards put forward earlier this year by the Lancet Diabetes and Endocrinology Commission would elevate the prevalence of obesity in the United States from roughly 40 percent to close to 70 percent. This research drew on information from over 300,000 individuals and revealed that the surge was particularly striking among seniors. The results further indicated that a substantial portion of those newly categorized under the fresh criteria are at elevated risk for severe health complications. The research appeared in JAMA Network Open.
‘We were already aware of an obesity crisis, but these numbers are staggering,’ remarked co-first author Lindsay Fourman, MD, an endocrinologist working in the Metabolism Unit within the Endocrinology Division of the Mass General Brigham Department of Medicine. ‘If nearly 70 percent of adults are now viewed as carrying excess body fat, it’s crucial to determine which interventions should take priority in addressing this widespread issue.’
Limitations of Relying Solely on BMI for Assessing Health Risks
For many years, the primary method for defining obesity has been body mass index (BMI), which is derived from a person’s height and weight measurements. Although BMI provides a straightforward approximation, it fails to account for the distribution of fat across the body. Alternative body measurement techniques—such as waist circumference, waist-to-height ratio, and waist-to-hip ratio—offer deeper insights by differentiating between fat and muscle mass, while pinpointing visceral fat that correlates with heightened disease susceptibility.
The new classification system identifies obesity through two primary pathways. First, those with an elevated BMI accompanied by at least one abnormal body measurement qualify as obese; the researchers term this ‘BMI-plus-anthropometric obesity.’ Second, even individuals with a standard BMI can be deemed obese if they exhibit at least two irregular body measurements, labeled ‘anthropometric-only obesity.’ Moreover, the framework distinguishes between preclinical and clinical obesity, where the latter involves physical limitations or organ damage stemming from obesity. These updated benchmarks have garnered support from no fewer than 76 groups, encompassing the American Heart Association and The Obesity Society.
Analysis Reveals Dramatic Surge in Obesity Prevalence
The study team reviewed data from participants in the National Institutes of Health’s All of Us Research Program, encompassing more than 300,000 people across the US. When applying the novel definition, a striking 68.6 percent of these individuals satisfied the obesity thresholds, in stark contrast to the 42.9 percent identified via the conventional BMI method. This entire uptick stemmed from cases of anthropometric-only obesity. Variations in obesity rates emerged by gender and ethnicity, yet age exerted the most profound influence, with almost 80 percent of those aged 70 and above fulfilling the updated criteria.
Elevated Health Dangers Among Those Newly Classified
Beyond prevalence, the investigation demonstrated that individuals with anthropometric-only obesity—previously overlooked by traditional standards—experienced substantially higher incidences of diabetes, heart disease, and death rates relative to those without obesity. Approximately half of all participants meeting the new obesity benchmarks were classified as having clinical obesity. Intriguingly, this proportion was only marginally less prevalent in the anthropometric-only group compared to the BMI-plus-anthropometric group.
‘BMI has long been known to have shortcomings as a standalone indicator of obesity since it overlooks fat placement in the body,’ explained senior author Steven Grinspoon, MD, who leads the Metabolism Unit in the Endocrinology Division at Mass General Brigham’s Department of Medicine. ‘Observing heightened cardiovascular and diabetes risks in this freshly identified obese population—previously not flagged as such—raises compelling inquiries regarding the suitability of obesity drugs and alternative therapies for them.’
Implications for Interventions and Ongoing Investigations
The authors emphasize the necessity for further research to elucidate the origins of anthropometric-only obesity and pinpoint the most promising treatment options. Their group has previously pioneered an intervention focused on shrinking waist size and intends to assess various therapeutic modalities for this expanded patient cohort.
‘Pinpointing excess adipose tissue is essential, especially as evidence mounts that even those with normal BMI but central fat buildup face amplified health threats,’ Fourman observed. ‘What truly counts is body composition, far beyond mere weight readings.’
