Similarity in Percent Body Fat Between White and Vietnamese Women: Implication for a Universal Definition of Obesity

Obesity (Impact Factor: 4.39).

ABSTRACT It has been widely assumed that for a given BMI, Asians have higher percent body fat (PBF) than whites, and that the BMI threshold for defining obesity in Asians should be lower than the threshold for whites. This study sought to test this assumption by comparing the PBF between US white and Vietnamese women. The study was designed as a comparative cross-sectional investigation. In the first study, 210 Vietnamese women ages between 50 and 85 were randomly selected from various districts in Ho Chi Minh City (Vietnam). In the second study, 419 women of the same age range were randomly selected from the Rancho Bernardo Study (San Diego, CA). In both studies, lean mass (LM) and fat mass (FM) were measured by dual-energy X-ray absorptiometry (DXA) (QDR 4500; Hologic). PBF was derived as FM over body weight. Compared with Vietnamese women, white women had much more FM (24.8 +/- 8.1 kg vs. 18.8 +/- 4.9 kg; P < 0.0001) and greater PBF (36.4 +/- 6.5% vs. 35.0 +/- 6.2%; P = 0.012). However, there was no significant difference in PBF between the two groups after matching for BMI (35.1 +/- 6.2% vs. 35.0 +/- 5.7%; P = 0.87) or for age and BMI (35.6 +/- 5.1% vs. 35.8 +/- 5.9%; P = 0.79). Using the criteria of BMI >/=30, 19% of US white women and 5% of Vietnamese women were classified as obese. Approximately 54% of US white women and 53% of Vietnamese women had their PBF >35% (P = 0.80). Although white women had greater BMI, body weight, and FM than Vietnamese women, their PBF was virtually identical. Further research is required to derive a more appropriate BMI threshold for defining obesity for Asian women.

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    ABSTRACT: The study of human variation in adiposity and lean mass is important for understanding core processes in human evolution, and is increasingly a public health concern as the "obesity epidemic" expands globally. The dominant measure of population differences in adiposity is Body Mass Index (BMI), which suffers from systematic biases across populations due to variation in the relationship between true body fat, height and weight. Here we develop simplified corrections for such anthropometric-based measures of adiposity that can take into account this population variation. These corrections derive from a recent model proposed by Burton that assumes humans accrue mass in two ways-growth in height that adds bone and muscle, and growth in body fat and the ancillary fat-free mass (FFM) needed to support this additional body fat. We analyze two ethnically diverse datasets with dual X-ray absorptiometry-measured (DXA) fat mass, assessing the fit of Burton's model and deriving novel corrections based on estimated musculoskeletal slenderness. The resulting model provides excellent fit to fat mass within populations (average R(2) = 0.92 for women and R(2) = 0.83 for men). World populations differ dramatically in musculoskeletal slenderness (up to a difference of 4.4 kg/m(2) ), as do men and women (differences of 3.3-4.5 kg/m(2) ), leading to clear population corrections. These findings point to a conceptually straightforward tool for estimating true differences in adiposity across populations, and suggest an alternative to BMI that provides a more accurate and theoretically based estimate of body fat than that traditionally derived from height and weight measures. Am J Phys Anthropol, 2013. © 2013 Wiley Periodicals, Inc.
    American Journal of Physical Anthropology 05/2013; 151(1). DOI:10.1002/ajpa.22258 · 2.51 Impact Factor
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    ABSTRACT: Context: Body weight is the most important anthropometric determinant of bone mineral density (BMD). Body weight is mainly made up of lean mass (LM) and fat mass (FM), and which component is more important to BMD has been a controversial issue. Objective: This study sought to compare the magnitude of association between LM, FM, and BMD by using a meta-analytic approach. Data Source: Using an electronic and manual search, we identified 44 studies that had examined the correlation between LM, FM, and BMD between 1989 and 2013. These studies involved 20 226 men and women (4966 men and 15 260 women) aged between 18 and 92 years. We extracted the correlations between LM, FM, and BMD at the lumbar spine, femoral neck, and whole body. The synthesis of correlation coefficients was done by the random-effects meta-analysis model. Results: The overall correlation between LM and femoral neck BMD (FNBMD) was 0.39 (95% confidence interval, 0.34 to 0.43), which was significantly higher than the correlation between FM and FNBMD (0.28; 95% confidence interval, 0.22 to 0.33). The effect of LM on FNBMD in men (r = 0.43) was greater than that in women (r = 0.38). In premenopausal women, the effect of LM on BMD was greater than the effect of FM (r = 0.45 vs r = 0.30); however, in postmenopausal women, the effects of LM and FM on BMD were comparable (r = 0.33 vs r = 0.31). Conclusion: LM exerts a greater effect on BMD than FM in men and women combined. This finding underlines the concept that physical activity is an important component in the prevention of bone loss and osteoporosis in the population.
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    ABSTRACT: The fate and transport of 2,3,7,8-tetrachloro-p-dibenzodioxin (TCDD) released into the environment of South Vietnam (SVN) as a consequence of the aerial application of the herbicidal defoliant Agent Orange (AO) were simulated for a generic upland forest scenario and followed over a 50-year period (1965, 1968 and 1970 onwards). Modeled concentrations of TCDD in the environment were then used as inputs to a human exposure model, which focused on long-term exposures via the food chain. Intake rates and body burdens of TCDD were estimated for adult males over the course of the simulation period and compared to available biomonitoring data. One of the most important factors determining the magnitude of the simulated human exposure to TCDD was the fraction of the chemical deposited directly to soil (where it was assumed to have a degradation half-life of 10 or 15years) relative to the fraction assumed to remain on/in the forest canopy following the spray application (where it was assumed to have a degradation half-life of ≤48h). The simulated body burdens under the various scenarios considered were broadly consistent with the biomonitoring data from SVN collected in the mid-1980s to late 1990s. Taken together, the modeling results and empirical data suggest that highly elevated exposures to TCDD (i.e., body burdens in the several 100s of pg/g lipid range and greater) were not common among people inhabiting upland forest locations in SVN sprayed with AO and that peak and average body burdens were broadly similar to those of the general population of the U.S. in the 1970s and early 1980s. The model-based assessment is consistent with the 'hot spot' hypothesis i.e., potential exposures to TCDD linked to activities conducted on or near former bases where AO was stored are greater than potential exposures in areas subjected to aerial spraying. Copyright © 2014 Elsevier B.V. All rights reserved.
    Science of The Total Environment 11/2014; 506. DOI:10.1016/j.scitotenv.2014.11.026 · 3.16 Impact Factor


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Mar 23, 2015