Effects of ethnicity, gender, obesity, and age on central fat distribution: Comparison of dual x-ray absorptiometry measurements in white, black, and Puerto Rican adults

Population based studies relying primarily upon anthropometric surrogates of fat distribution have shown that central or upper-body adiposity is related to ethnicity, gender, age, and total body fatness. As an improvement over anthropometry, dual x-ray absorptiometry (DXA) provides more precise measurements of fat mass (FM) in the total body and trunk. DXA was performed on 510 apparently healthy White (81 females (f), 64 males (m)), Black (94 f, 79 m), and Puerto Rican (102 f, 100 m) adults aged 20-75 years in order to determine and compare the effects of race, gender, age, and total FM on trunk FM. Trunk FM was greater for Blacks and Puerto Ricans than Whites, irrespective of gender (P < 0.014). Puerto Rican males and females had a greater proportion of fat in the trunk (%TrFM) than Whites or Blacks (P < 0.001), and Whites and Blacks were similar with respect to %TrFM (P > 0.67). Females had less %TrFM than males in all three ethnic groups (all P < 0.001). Based on multiple regression analysis, ethnicity did not affect the relationship of trunk and total FM among males (P > 0.16), but the coefficient for total FM was larger for Puerto Rican compared to Black females (P = 0.043). Trunk FM increased with age in Whites and Puerto Ricans (P < 0.02), but not Blacks (P > 0.24). The effects of age did not differ by gender or ethnicity among Whites and Puerto Ricans (P > 0.10). Adjustment for total FM and age eliminated ethnic and gender differences in trunk FM (all P > 0.37). The results suggest that the high levels of central adiposity observed among Blacks and Hispanics relative to Whites reflect patterns of generalized obesity observed in the respective populations. Patterns of accumulation of truncal FM with increasing age and obesity may not be generalizable to all ethnic groups. Am. J. Hum. Biol. 10:361-369, 1998. © 1998 Wiley-Liss, Inc.