Association of basal metabolic rate with respiratory function among middle-aged obese and nonobese subjects

Background: Obesity is proved to be a comorbid condition in various metabolic, cardiovascular, and pulmonary disorders. Only a few investigations analyzed the relationship between basal metabolic rate (BMR) and lung function in middle-aged obese individuals. Objectives: The aim of this study was to determine the relationship of BMR to that of pulmonary functions among middle-aged obese subjects. Materials and Methods: This cross-sectional study was undertaken in obese and nonobese healthy subjects (50 each) of age 35-55 years. Body mass index (BMI), body fat percentage (BF%), fat mass (FM), and fat-free mass (FFM) were estimated, and BMR was calculated using predicted equations. Spirometric measures such as forced expiratory volume in one second (FEV1), forced vital capacity (FVC), FEV1/FVC, and peak expiratory flow rate (PEFR) were measured. Maximum voluntary ventilation (MVV) and mean forced expiratory flow during the middle of FVC (FEF25%-75%) were determined. Descriptive statistics, t test (unpaired), and Pearson's correlation test were used for the analysis of the variables. Values of P ≤ 0.05 were considered statistically significant. Results: Mean BMR among obese was significantly higher than nonobese. The pulmonary function parameters FVC, FEV1, and FEF25%-75% were significantly reduced in obese. A significant positive correlation of BMR was found with FVC, FEV1, PEFR, FEF25%-75%, and MVV among both obese and nonobese. An inverse correlation existed between BMR and FEV1-to-FVC ratio in the study participants. Conclusions: Pulmonary functions are more closely associated with fat distribution than with the extent of obesity. The study outcome suggests that, in the context of early lung function alterations in the middle-aged obese subjects, it is necessary to take into account the BMR and body composition instead of BMI alone.