Associations of BMI with Self-Perceptions of Weight Status among Firefighters

Stefanos N. Kales MD, MPH, Antonios J. Tsismenakis MA, and Sara A. Pyle PhDHarvard School of Public Health, Boston, MA (SNK, AJT); The Cambridge Health Alliance, Harvard Medical School, Cambridge, MA (SNK,

AJT); Boston University School of Medicine, Boston, MA (AJT); National Development and Research Institutes, Kansas City, MO (SAP)

Stefanos N. Kales, MD, MPH - Employee & Industrial Medicine - The Cambridge Health Alliance - 1493 Cambridge St – Suite 427 - Cambridge, MA 02139 - Phone: 617-665-1580 - Fax: 617-665-1672 - Email: skales@challiance.org

IntroductionApproximately 45% of on-duty deaths among firefighters are attributable to cardiovascular events, and most of these incidents occur during high stress/exertion in susceptible firefighters with modifiable risk factors, including obesity. Obesity is also well-recognized to mediate risk through effects on other modifiable factors (blood pressure, lipids, glucose, etc). Several previous studies of firefighters have documented a high prevalence of overweight/obesity, as well as increases in average body mass index (BMI) over recent decades. Little is known, however, about firefighters’ self-perceptions of weight status and how these vary across BMI categories.

MethodsBMI and questionnaire data were collected from 377 consecutive medical examinations of firefighters from Kansas and Missouri. Cross-sectional analyses were performed across internationally-defined BMI categories (underweight, normal weight, overweight, obese) and self-perceived weight categories (“underweight/skinny,” “healthy/normal/muscular,” “overweight,” “obese/fat”). Analyses were performed using 2-tests for categorical variables. Statistical significance was determined by p<0.05.

Results:None of the firefighters were underweight by BMI, 14% were of normal weight, 48% were overweight, and 38% were obese. Two percent considered themselves to be underweight, 52% healthy/normal/muscular, 40% overweight, and 4% obese/fat.

Agreement between self-perceived weight category and measured BMI decreased markedly as BMI category increased: 87% among those with normal BMI; 29% among the overweight; and 10% among the obese (p<0.001). None of the

normal weight, 2 of the overweight, and 5 of the obese firefighters elected not to answer the question about weight status. In parallel to the firefighters’ self-perceptions, 89%, 22%, and 9%, of their primary care physicians had correctly classified the firefighters as normal weight, overweight, or obese, respectively, when these reports were compared to BMI categories (p<0.001). Additionally, 20% of overweight and 14% of obese subjects reported that their doctors had not commented on their weight.

Self-perceptions regarding desired weight change were more consonant with measured BMI: 46% of overweight and 52% of obese firefighters wanted to lose weight over the next year.

Conclusions:In agreement with previous studies, overweight and obesity were highly prevalent in our sample. However, when queried about weight status, the accuracy of firefighters’ self-perceptions was inversely related to measured BMI category. The majority (69% of overweight and 86% of obese) considered themselves to belong in lower weight categories.

Likewise, heavier subjects more frequently reported having had their weight misclassified or not mentioned at all by their primary care physicians. Approximately half of the overweight and obese subjects denied any desire to lose weight, which is likely influenced by the high prevalence of incorrect self- and physician perceptions of weight status.

The fire service and clinicians should address weight status in firefighters by using objective measures of adiposity and providing frank feedback to help guide nutrition and exercise counseling.

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Figure 1. Prevalence of Weight Status by BMI vs. Self Report