A newly proposed definition of obesity suggests that waist circumference may be as important as body weight or body mass index (BMI) for assessing health risks. Under this updated framework, approximately 75% of U.S. adults could be classified as obese, a significant increase from the 40% identified by BMI alone. This shift aims not to label individuals but to enhance early identification of health risks, according to experts.
Dr. Kamil Faridi, a cardiologist with Yale Medicine, emphasizes the importance of abdominal fat, stating, “Factors such as an expanded waistline really are associated with an increased risk for poor health outcomes.” He notes that obesity adversely affects nearly every organ system, particularly the cardiovascular system.
The traditional definition of obesity, based on BMI calculations, has long categorized individuals with a BMI of 30 or higher as obese. The new criteria, endorsed by over 75 medical organizations, include a BMI threshold of 40 or higher, while also considering waist circumference and other clinical measures.
Broadening the Definition
The updated criteria incorporate additional factors, such as:
– Waist circumference
– Waist-to-hip and waist-to-height ratios
– Evidence of weight-related conditions, including high blood pressure, elevated blood sugar, or abnormal cholesterol levels
The definition distinguishes between two categories: clinical obesity, which leads to significant health complications, and preclinical obesity, where excess fat poses a future risk without current symptoms.
Dr. Faridi points out that defining obesity in this manner is crucial because it influences various aspects of healthcare, including insurance coverage, access to medications, and eligibility for treatments such as bariatric surgery and GLP-1 receptor agonists like Wegovy and Zepbound.
While clinicians have not yet widely adopted this new definition, further research is planned to establish its application across different age groups. Notably, a study led by Dr. Faridi found that over 90% of adults over the age of 50 would meet the criteria for obesity under the new definition.
Health Risks Associated with Abdominal Fat
A significant concern is the accumulation of visceral fat, which surrounds vital organs such as the liver and pancreas. This type of fat is particularly concerning because it is metabolically active and contributes to inflammatory processes. Dr. Faridi explains, “BMI doesn’t address how much adipose tissue a person has, or importantly, where that fat is located.”
Research shows that obesity is linked to more than 200 health conditions, including heart disease, diabetes, high blood pressure, and certain cancers. The waist circumference thresholds for adults differ by ethnicity, with lower cutoffs recommended for Asian adults—specifically 31.5 inches for women and 35.4 inches for men—due to a higher risk of diabetes at lower body weights.
The implications of this new definition are significant. According to a study published in Jama Network Open, the prevalence of obesity in the U.S. could rise to 75.2% when waist circumference is factored in, compared to the 40% previously identified through BMI alone. Researchers utilized data from the National Health and Nutrition Examination Survey (NHANES), which included over 14,000 participants.
Dr. Faridi highlights that many individuals classified as “normal weight” or “overweight” by BMI alone may actually meet obesity criteria when waist measurements are taken into account. He stresses the importance of being aware of key health indicators such as blood pressure, blood sugar, cholesterol levels, body weight, and waist circumference.
Individuals can easily measure their waist size at home by standing upright and placing a tape measure midway between the lowest rib and hip bone. It is recommended to exhale normally before taking the measurement.
While lifestyle changes remain essential for managing weight and preventing obesity, Dr. Faridi notes that monitoring waist size can be particularly helpful during stressful periods. “If someone has excess body weight at any point, earlier intervention can prevent disease and improve long-term health,” he explains.
As the medical community continues to evaluate this new definition and its impact on treatment and diagnosis, the emphasis remains on early detection and management of obesity to enhance overall health outcomes.
