Respiratory function is impaired in obesity but there are limitations with body mass
index and skin-fold thickness in assessing this effect. The present authors 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 measurements of total body fat.
In total, 107 subjects (55 female, 51.4%) aged 20–50 yrs with no respiratory disease were
recruited. Respiratory function tests, anthropometric measurements 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 females but positively associated in males. This
disappeared after adjustment in females but remained in males.
The effects of thoracic and abdominal body fat on respiratory function are comparable but
cannot be separated from one another.