- Almost 19% of U.S. adults previously defined as overweight based on BMI alone were newly considered to have obesity by the EASO diagnostic framework.
- The EASO classification takes into account BMI, waist-to-hip ratio, and medical, functional, or psychological comorbidities.
- The most prevalent complications among newly identified people with obesity were hypertension, arthritis, diabetes, and cardiovascular disease.
More adults would be diagnosed with obesity when using a framework recently outlined by the European Association for the Study of Obesity (EASO) that goes beyond body mass index (BMI) alone.
The 2024 framework takes a more "holistic" approach to the treatment of obesity by accounting for both increased fat mass accumulation and its impact on health, wrote Orna Reges, PhD, of Ariel University in Israel, and colleagues in the Annals of Internal Medicine.
The new diagnostic criteria moved 18.8% of U.S. adults who were previously defined as overweight based on BMI alone (25 to <30) into the obesity category, which grew to encompass more than half of all adults.
"The EASO framework introduces clinical components to its definition, which along with BMI and WHtR [waist-to-hip ratio], may provide a more sensitive tool for diagnosing obesity disease earlier than BMI alone," they pointed out.
EASO's weight categories are as follows:
- Normal weight: BMI 18.5 to <25
- Overweight: BMI 25 to <30, plus WHtR <0.5 or no medical, functional, or psychological complications
- Obesity: BMI ≥30 or BMI 25 to <30 with WHtR ≥0.5 and at least one medical, functional, or psychological comorbidity, including hypertension, cardiovascular disease, diabetes, arthritis, renal disease, chronic obstructive pulmonary disease, and depression
The most prevalent complications among the newly identified people with obesity included hypertension (79.9%), arthritis (33.2%), diabetes (15.6%), and cardiovascular disease (10.5%).
But when compared with normal weight individuals overall, individuals with EASO-defined overweight had a 46% lower mortality risk. Those newly classified as having obesity didn't have an excess mortality risk (HR 0.98, 95% CI 0.87-1.10), whereas those with BMI-classified obesity (BMI ≥30) had a 19% higher mortality risk.
When compared with normal weight individuals free of comorbidities, there was a higher mortality risk both for people with newly classified obesity (HR 1.50, 95% CI 1.20-1.88) and BMI-defined obesity (HR 1.82, 95% CI 1.46-2.27). However, those of normal weight with comorbidities also had an excess mortality risk (HR 1.74, 95% CI 1.34-2.22).
The similarity in mortality risk observed between newly reclassified adults with obesity and those with normal weight "may, in part, be explained by the lack of adjustment for morbidity, which is embedded in the EASO definition, and underlying illness among the normal-weight group," the researchers explained. "Some persons may have experienced unintentional weight loss due to undiagnosed conditions, such as gastrointestinal disorders, hyperthyroidism, or neurologic diseases, which can increase the risk for death and artificially inflate mortality rates in this group."
"Although patients diagnosed with cancer were excluded, these other conditions may still introduce negative survival bias," they noted.
The similarly in excess mortality risk may also "simply reflect greater illness burden rather than higher risk posed by excess adiposity above what is captured by BMI and preexisting comorbidities alone," argued an accompanying editorial by Christina Wee, MD, MPH, senior Annals deputy editor, and co-authors.
For the cross-sectional and longitudinal analysis, Reges' group used a sample of 44,030 adults from National Health and Nutrition Examination Survey iterations from 1999-2018 along with linked mortality data.
Based on BMI alone, 31.3% of individuals in the entire study population were considered normal weight, 33.3% had overweight, and 35.4% had obesity. But under the new framework, more than half of the study population were now defined as having obesity (54.2%). More men (21.9%) than women (15.6%) were newly classified as having obesity.
Traditional BMI-calculated obesity has "many shortcomings," noted Wee's group, adding that accurately defining obesity on the individual level is "uniquely challenging."
"Assessing obesity risk has become increasingly important as health payers consider approaches to ration effective but costly weight loss medications," they said.
Because of this, there has been a recent push to move beyond sole reliance on BMI by several groups worldwide.
Earlier this year, a global commission, endorsed by more than 75 global medical organizations, similarly argued for a more nuanced approach to diagnosing obesity that doesn't exclusively rely on BMI, advocating for use of at least one additional anthropometric measure like waist circumference, WHtR, or waist-to-height ratio -- or direct fat mass measurement by dual-energy x-ray absorptiometry (DEXA) or bioimpedance when defining obesity.
Another consensus statement, released in 2020 by the International Atherosclerosis Society (IAS) and the International Chair on Cardiometabolic Risk (ICCR) Working Group, suggested using waist circumference as a proxy for abdominal adiposity.
While these various approaches offer a few alternatives to BMI alone, Wee's group called for more head-to-head comparisons of the performance of these different tools in diverse populations before building consensus on the best universal approach to define and risk stratify obesity.
"To be broadly applicable, the optimal framework should include only measures that are readily accessible, can be implemented in both high- and low-resource settings, and are measured in a standardized and reproducible way," they said. "With the expansion of effective obesity treatment options, it's time we match our advances in therapeutics with improvements in diagnosis and risk assessment."
Disclosures
The study was funded by Ariel University and the Holon Institute of Technology in Israel.
Primary Source
Annals of Internal Medicine
Source Reference: Dicker D, et al "Implications of the European Association for the Study of Obesity's new framework definition of obesity: Prevalence and association with all-cause mortality" Ann Intern Med 2025; DOI: 10.7326/ANNALS-24-02547.
Secondary Source
Annals of Internal Medicine
Source Reference: Wee CC, et al "Staging obesity risk beyond body mass index: progress made but more to do" Ann Intern Med 2025; DOI: 10.7326/ANNALS-25-02327.
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