Effects of Obesity on Pulmonary Function in Obese, Overweight, and Normal Students

Obesity is a major public issue. According to the World Health Organization (WHO), the prevalence of obesity and overweight would increase to 1.5 million individuals by 2015. Obesity is an important risk factor for many cardiovascular diseases, hypertension, type 2 diabetes, osteoarthritis, some cancers. In addition, obesity and percent of body fat seem to be associated with respiratory problems, although the mechanism of this correlation is not very clear. The purpose of this study was examining the relationship between anthropometric characteristics, body composition, and lung function in obese, overweight, and normal students. In this study, 283 secondary school students in Isfahan, Iran [age: 12.79 ± 0.88 years old, body mass index (BMI): 20 ± 39.9 kg/m2] were selected using cluster random sampling. Subjects were divided into 3 groups of obese (BMI ≥ the 95th percentile; n= 50), overweight (the 85th ≤ BMI ≤ the 95th percentile; n = 62), and normal (the 15th percentile ≤ BMI ≤ the 85th percentile; n = 171). Pulmonary function was assessed using Spirometric methods. In addition, anthropometric characteristics and body composition were measured. Our results showed the three groups of normal, overweight and obese students to be significantly different in terms of the average lung capacity and volume. Moreover, significant negative correlations were observed between anthropometric characteristics and indicators of body composition and lung function. Least significant difference post hoc test results also showed that lung function in normal students was greater than overweight and obese students. In addition, the prevalence of normal weight, overweight, and obesity among the studied students were 60.4, 21.9, and 17.7, respectively. Based on our results, obesity has a specific effect on lung function and reduces lung capacity and volume. However, the exact mechanism has not been well understood. Therefore, further studies in this field are required.