Whole-Body MRI and Ethnic Differences in Adipose Tissue and Skeletal Muscle Distribution in Overweight Black and White Adolescent Boys

SoJung Lee,Silva Arslanian,Fernando E. Boada,Jennifer L. Kuk,YoonMyung Kim

doi:10.1155/2011/159373

Abstract

It is unclear whether ethnic differences exist in adipose tissue (AT) and skeletal muscle (SM) distribution in black and white youth. Investigation into the pattern of AT and SM distribution in black versus white youth may provide insight into the previously reported health disparities between these ethnicities. Therefore, we examined total and regional AT and SM in overweight black and white boys. The study sample included overweight black (n = 19) and white (n = 21) boys (11–18 yr, BMI ≥ 85th) whose body composition was evaluated using whole-body MRI. Despite similar age, Tanner stage, and BMI, black boys had significantly (P < .05) less visceral AT than white boys and more (P < .05) total and lower-body subcutaneous AT (SAT) in both absolute (kg) and relative (%) terms. There was a main effect (P < .05) of ethnicity on the relationship between total and regional AT, such that for a given amount of total body AT (kg), black boys had a greater (P < .05) lower-body SAT and less visceral AT than their white peers. For a given amount of total SM, black boys had more (P < .05) SM in the thigh. Compared with overweight white boys, overweight black boys have less visceral fat, more subcutaneous fat, and more thigh skeletal muscle.

Highlights

It is well-established that visceral adipose tissue (AT) is a strong risk factor for many obesity related comorbidities, independent of overall obesity in children and adolescents [1,2,3]
When expressed relative to total AT, black boys had a significantly (P < .05) higher % leg subcutaneous AT (SAT) and lower % visceral AT compared with white boys (Figure 1)
In comparison to white boys, black boys had higher total and lower-body SAT for a given amount of total AT

Summary

Introduction

It is well-established that visceral adipose tissue (AT) is a strong risk factor for many obesity related comorbidities, independent of overall obesity in children and adolescents [1,2,3]. Ethnic differences in abdominal AT distribution have been noted in adults [4,5,6] and in the pediatric age group [7,8,9,10], such that black children and adolescents have lower visceral AT area (cm2) than their white peers despite similar BMI or total fat. Sisson et al [11] have shown that white boys and girls have higher subcutaneous AT estimated by skinfold-thicknesses than their black peers, while others report no differences between black and white children [12]. Alterations in SM morphology (e.g., increased lipid accumulation between muscle bundles (intermuscular AT: IMAT)) are shown to be associated with decreased insulin sensitivity [15].

Methods

Results

Conclusion