The effect of adiposity measured by dual-energy x-ray absorptiometry on lung function

¹ Respiratory Research Unit, Dept of Medical and Surgical Sciences, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
² Dept of Medical and Surgical Sciences, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
³ Dept of Preventive and Social Medicine, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
⁴ School of Physiotherapy, University of Otago, Dunedin, New Zealand

^* To whom correspondence should be addressed. E-mail: robin.taylor{at}stonebow.otago.ac.nz.

	Abstract

Respiratory function is impaired in obesity but there are limitations with body mass index and skinfold thickness in assessing this effect. We hypothesised that the regional distribution of body fat and lean mass, as measured by dual energy X-ray absorptiometry (DXA), might be more informative than conventional measures of total body fat.

A total of 107 subjects (55 female, 51.4%) aged 20-50 with no respiratory disease were recruited. Respiratory function, anthropometric measures and a DXA scan were performed. Partial correlation and linear regression analyses were used to explore the effect of adiposity and lean body mass on respiratory function.

The majority of respiratory function parameters were significantly correlated with DXA and non-DXA measurements of body fat. Neither thoracic nor abdominal fat had a greater effect. There were some differences in the effect of adiposity between the sexes. Respiratory function was negatively associated with lean body mass in women but positively associated in men. This disappeared after adjustment in women but remained in men.

The effects of thoracic and abdominal body fat on respiratory function are comparable cannot be separated from one another.