Chest
Volume 107, Issue 5, May 1995, Pages 1298-1302
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Clinical Investigations: Pulmonary Function
The Effect of Body Fat Distribution on Pulmonary Function Tests

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Although the influence of obesity on pulmonary function tests has been examined, the role of body fat distribution has received limited attention. Pulmonary studies of patients severely affected by upper body obesity suggest they have more severely compromised lung volumes than obese patients with lower body obesity. We examined 42 healthy but normal or mildly obese men to determine if body fat distribution influences pulmonary function tests.

Multiple measures of adiposity showed a significant inverse relationship with both spirometry and static lung volumes. However, the biceps skinfold thickness had the strongest inverse relationship with total lung capacity (TLC) compared to other anthropometric measures. The waist-to-hip ratio (WHR) demonstrated a significant inverse relationship with static lung volumes only when controlling for cigarette smoking. However, comparing pulmonary function tests between patients with a WHR less than 0.950 (lower body fat distribution) and subjects with a WHR of 0.950 or greater (upper body fat distribution) revealed that FVC, FEV1, and TLC were significantly lower in the patients with upper body fat distribution. Stepwise multiple regression analysis was done using all anthropometric variables and age which generated predictive equations that included the biceps skinfold thickness for residual volume (RV) and TLC. This suggests that upper body fat distribution may be associated with a modest impairment of lung volumes in normal and mildly obese men. Until the findings of this study can be applied to a larger, ethnically and anthropometrically diverse population, and to women, we believe caution is warranted when standard equations are used to predict pulmonary function tests in an anthropometrically diverse population.

Section snippets

Materials and Methods

Forty-four healthy male firefighters were referred for fitness evaluations, none of which had any known medical problems. Both current and exsmokers were included in the group. Evaluation included spirometry, lung volumes, and body fat determination, and a fasting serum sample was obtained to evaluate triglycerides, cholesterol, and glucose levels. Our study was reviewed and approved by the Human Studies Committee of the University of Louisville (Kentucky) School of Medicine. Informed consent

Results

Demographic characteristics of the subjects and the results of spirometric and lung volume testing are shown in Table 1. Forty-four subjects underwent spirometric testing. Two firefighters who did not undergo hydrostatic weighing, also did not have lung volumes measured. Therefore, 42 subjects had lung volumes measured in addition to their spirometry. The two subjects who did not have lung volumes measured were excluded from this study. None of the subjects were severely obese (150% or greater

Discussion

To our knowledge this is the first study examining the effect of body fat distribution on pulmonary function tests in lean and mildly obese men. In this investigation, we found that a simple measure of body fat distribution, primarily the biceps skinfold, improved prediction of normal pulmonary measurements in nonobese adults compared with predictions based on general measurements.12,13 This extends the preliminary findings in morbidly obese patients, suggesting that body fat distribution may

Acknowledgments

This work was supported in part by the Allen & Hanburys division of Glaxo, Inc. The authors wish to thank Bryant Stamford, PhD, for his advice and assistance in the completion of this study.

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