Sex differences in visceral adipose tissue volume among African Americans

Abstract

Background: Men are believed to have more visceral adipose tissue (VAT) than women have, but studies in African Americans that measured VAT from a single computed tomography (CT) slice found no sex difference. Objective: We used a serial-slice CT scan to investigate whether there is a sex difference in VAT volume among African Americans. Design: Single-slice CT measurements of VAT area at lumbar spine L2-3 and L4-5 levels were taken in 110 African Americans (44 men, 66 women). In 59 subjects (24 men, 35 women), VAT volume was also measured with contiguous CT slices from the diaphragm to the iliac crest. Fat mass was determined by dual-energy X-ray absorptiometry. Results: Men and women had similar ages (x̄ ± SD: 36.1 ± 7.8 and 35.6 ± 7.8 y, respectively) and body mass indexes in kg/m2 (29.5 ± 6.9 and 32.0 ± 8.9). The percentage of body fat was lower (P < 0.0001) in men (21.8 ± 7.3%) than in women (37.4 ± 7.9%). The VAT volume was greater (P = 0.01) in men (1443 ± 931 cm3) than in women (940 ± 82 cm3). There was no sex difference in unadjusted VAT area at L2-3 (men, 88.6 ± 63.5 cm2: women, 57.2 ± 45.4 cm2) or L4-5 (men, 65.6 ± 53.3 cm2; women, 55.0 ± 38.3 cm2). After adjustment for percentage of body fat or fat mass, men had larger VAT area at both levels (P < 0.01). After adjustment for body mass index, the sex difference in VAT area was detectable at L2-3 (P < 0.001) but not at L4-5 (P = 0.22). Conclusions: VAT volume is greater in men than in women. Detection of sex differences in VAT area among African Americans on single-slice CT requires adjustment for body fat content. At L2-3, adjustment for body mass index alone is adequate to detect sex differences in VAT.