BMI Cutoff of 30 for Obesity May Be Too High for Middle-Aged, Older Adults

FRIDAY, May 31, 2024 (HealthDay News) -- The optimal body mass index (BMI) cutoff point appears to be 27 kg/m² for detecting obesity in middle-aged and older adults, according to a study presented at the annual meeting of the European Congress on Obesity, hosted by the European Association for the Study of Obesity from May 12 to 15 in Venice, Italy.

Marwan El Ghoch, M.D., from the University of Modena and Reggio Emilia in Italy, and colleagues used data from adults (aged 40 to 80 years; 1,087 with normal weight; 1,826 with overweight; 1,887 with obesity) who were referred for clinical nutritional counseling to assess the validity of the 30 kg/m² cutoff as an indicator of obesity across the lifespan.

The researchers found that the most appropriate BMI cutoff point for identifying obesity based on body fat was 27.08 kg/m² in women and 27.36 kg/m² in men. This cutoff had an area under the curve of 0.89 and 0.88, respectively, for women and men, indicating the excellent discriminating ability of BMI for detecting obesity. These cutoff points showed a high sensitivity (80.69 percent) and specificity (83.63 percent), indicating a low chance of false negatives and false positives.

"Our real-world study in a clinical setting in Italy shows that the optimal BMI cutoff point (27 kg/m²) for adults aged over 40 is significantly lower than the widely used one-size-fits-all threshold (30 kg/m²)," El Ghoch said in a statement. "It's likely that the changes in body composition across the lifespan, which seem to occur without a meaningful change in body weight, lead to higher adiposity at a lower BMI."

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