Healthy Body Mass Index Values Often Underestimate Body Fat in Men with Spinal Cord Injury

Objective: To examine the relation between body mass index (BMI) and adiposity in men with spinal cord injury (SCI).

Design: Cross-sectional study.

Setting: Outpatient study in 2 centers in New Zealand.

Participants: Nineteen men with traumatic SCI were age-, height-, and weight-matched with 19 able-bodied men.

Interventions: Not applicable.

Main Outcome Measures: BMI (kg/m(2)) and dual-energy x-ray absorptiometry measures of total and regional lean tissue mass and fat mass.

Results: Although the groups had similar BMIs, the total lean tissue mass was 8.9kg lower (95% confidence interval [CI], -12.7 to -5.2; P<.001) whereas total fat mass was 7.1kg greater (95% CI, 1.3-12.8; P<.05) in the SCI group. Body fat percentage was 9.4% (95% CI, 3.6-15.1; P<.01) greater in the SCI group. Regional measures showed a similar pattern. Truncal fat mass increased 3.7kg (95% CI, 0.5-6.9; P<.05) in the SCI group compared with controls.

Conclusions: Body fat mass was greater for any given BMI in the SCI group. Many patients with SCI do not appear to be obese, yet they carry large amounts of fat tissue. BMI is widely used to estimate adiposity, but it may underestimate body fat in men with SCI.