Browsing by keyword "Body Fat Distribution"

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    • Adipocyte lineages: tracing back the origins of fat
      Sanchez-Gurmaches, Joan; Guertin, David A. (2014-03-01)
      The obesity epidemic has intensified efforts to understand the mechanisms controlling adipose tissue development. Adipose tissue is generally classified as white adipose tissue (WAT), the major energy storing tissue, or brown adipose tissue (BAT), which mediates non-shivering thermogenesis. It is hypothesized that brite adipocytes (brown in white) may represent a third adipocyte class. The recent realization that brown fat exist in adult humans suggests increasing brown fat energy expenditure could be a therapeutic strategy to combat obesity. To understand adipose tissue development, several groups are tracing the origins of mature adipocytes back to their adult precursor and embryonic ancestors. From these studies emerged a model that brown adipocytes originate from a precursor shared with skeletal muscle that expresses Myf5-Cre, while all white adipocytes originate from a Myf5-negative precursors. While this provided a rational explanation to why BAT is more metabolically favorable than WAT, recent work indicates the situation is more complex because subsets of white adipocytes also arise from Myf5-Cre expressing precursors. Lineage tracing studies further suggest that the vasculature may provide a niche supporting both brown and white adipocyte progenitors; however, the identity of the adipocyte progenitor cell is under debate. Differences in origin between adipocytes could explain metabolic heterogeneity between depots and/or influence body fat patterning particularly in lipodystrophy disorders. Here, we discuss recent insights into adipose tissue origins highlighting lineage-tracing studies in mice, how variations in metabolism or signaling between lineages could affect body fat distribution, and the questions that remain unresolved. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.

    • Height, adiposity and body fat distribution and breast density in young women
      Dorgan, Joanne F.; Klifa, Catherine; Shepherd, John A.; Egleston, Brian L.; Kwiterovich, Peter O. Jr.; Himes, John H.; Gabriel, Kelley P.; Van Horn, Linda; Snetselaar, Linda G.; Stevens, Victor J.; et al. (2012-07-16)
      INTRODUCTION: Breast density is one of the strongest risk factors for breast cancer, but determinants of breast density in young women remain largely unknown. METHOD: Associations of height, adiposity and body fat distribution with percent dense breast volume (%DBV) and absolute dense breast volume (ADBV) were evaluated in a cross-sectional study of 174 healthy women, 25-29 years old. Adiposity and body fat distribution were measured by anthropometry and dual-energy x-ray absorptiometry (DXA), while %DBV and ADBV were measured by magnetic resonance imaging (MRI). Associations were evaluated using linear mixed effects models. All tests of statistical significance are 2-sided. RESULTS: Height was significantly positively associated with %DBV but not ADBV; for each standard deviation (SD) increase in height, %DBV increased by 18.7% in adjusted models. In contrast, all measures of adiposity and body fat distribution were significantly inversely associated with %DBV; a SD increase in body mass index (BMI), percent fat mass, waist circumference and the android:gynoid fat mass ratio (A:G ratio) each was associated significantly with a 44.4% - 47.0% decrease in %DBV after adjustment for childhood BMI and other covariates. Although associations were weaker than for %DBV, all measures of adiposity and body fat distribution also were significantly inversely associated with ADBV before adjustment for childhood BMI. However, after adjustment for childhood BMI only the DXA measures percent fat mass and A:G ratio remained significant; a SD increase in each was associated with a 13.8% - 19.6% decrease in ADBV . In mutually adjusted analysis, percent fat mass and the A:G ratio remained significantly inversely associated with %DBV, but only the A:G ratio was significantly associated with ADBV; a SD increase in A:G ratio was associated with a 18.5% decrease in ADBV. CONCLUSIONS: Total adiposity and body fat distribution are independently inversely associated with %DBV, whereas in mutually adjusted analysis only body fat distribution (A:G ratio) remained significantly inversely associated with ADBV in young women. Research is needed to identify biological mechanisms underlying these associations.