Obesity and lung capacity among healthy employees of a regional urban medical college in orissa, India: Is there a correlation?

Obesity associated restrictive lung capacity is poorly understood, notably in an otherwise healthy population. To evaluate this relationship, we recruited only non-smokers without any pulmonary disorders and examined their body mass index (BMI) and standard pulmonary tests (fev1/fvc ratio and maximum voluntary ventilation in the 1st 15 seconds or MVV15).

We enrolled a convenient sample of 81 healthy non-smokers following consent and eligibility determination during a three-month period from employees at a regional medical college offering both medical education and tertiary health care. Participants were 51% females, mean age 29.8 years, with a mean BMI of 26.3 kg/m2. Mean FEV1/FVC ratio was 93.5 while mean MVV15 was 22 liters. About a quarter (23.5%) were obese per CDC categories.

Overall, BMI was inversely correlated with MVV15 (r=-0.24, p=0.03) but not with FEV1/FVC ratio (r= 0.1, p=ns). Analysis of mean MVV15 stratified by BMI categories showed an inverse (but not statistically significant) gradient MVV15 by ascending obesity categories (normal-overweight-obesity). In one multiple regression analyses, after adjusting for age, gender, FEV1/FVC ratio, overall BMI contributed to a quarter of a point lowering of MVV15 ( beta=-0.248, t=2.36, p=0.02), with the model explaining 26% of variance, while in a separate equation with same covariates, those classified as obese contributed almost a 4-point reduction in MVV15 (beta=3.83, t=2.73, p=0.008), with the latter model explaining 28% of variance in MVV15.

Obesity in otherwise healthy individuals may influence restrictive pulmonary function due to differential distribution of adipose tissues in the chest and abdomen, which needs further investigation.