Accuracy of body mass index-defined overweight in fire fighters

Overweight, obesity and weight gain are significant problems in the U.S. fire service. While classification of obesity using body mass index (BMI) has demonstrated accuracy and low rates of false positives when compared with body fat percentage (BF%)-based standards, no studies have examined the accuracy of BMI-based overweight and normal weight status with other comparable body composition indices.

To compare overweight and normal weight BMI categories with BF% standards from the American Council on Exercise and analogous waist circumference (WC) categories and to examine rates and types of misclassification in fire fighters.

Data were collected from 11 randomly selected career fire departments in the International Association of Fire Chief's Missouri Valley Region. Demographics, occupational history, and body composition indices (weight, BF% and WC) were obtained from male career fire fighters who were categorized as normal weight or overweight based on BMI.

There were 293 participants of whom 92 had normal BMI. There were low rates of false positives (12%) and moderate rates of false negatives (22%) when comparing BMI categories to the compar able BF% categories. However, using WC as the standard resulted in very high rates of false positives (63%) and very low rates of false negatives (5%).

BMI-based overweight status was associated with significant errors in classification depending on the standard to which it was compared.