Brown fat cells are smaller in size and quantity and derive their color from the high concentration of mitochondria for energy production and vascularization of the tissue. It acts as a protective padding around all vital organs in the body. (7), it was estimated that activated BAT thermogenesis contributed 4.5% to whole-body energy expenditure, which was considered to be significant (23) and commensurate with the goal of exploiting BAT to burn excess calories stored in WAT for weight loss in obesity and type 2 diabetes (3). The main adipose depots of interest are found in the abdomen and can be divided into the SAT and VAT, and the visceral tissue can again be divided into omental and mesenteric, the latter being the more deeply buried depot surrounding the intestine (Figure 1). In humans, small areas are found in the thorax region (supraclavicular), and in the chest and abdomen [44]. Therefore, little fat will be burned during hard exercise over short time periods, like a football game. All rights reserved. Another estimate, which has not been reported in animal studies, is the fraction of generated heat that would diffuse outwardly to warm a contiguous organ. Likewise, an increase in gluteofemoral tissue size has been connected to increase in HDL-cholesterol and decrease in total- and LDL-cholesterol levels in several studies [83–85]. The distribution of BAT in warm-blooded animals provides the basis for understanding the functional relevance of the anatomic locations of human BAT. Figure 3A and B shows the release of heat from bilateral cervical-axillary BAT upon its acute activation by immersion of an 7-year-old child’s left hand into cool water at 20°C. imaginable degree, area of Epicardial adipose tissue (EAT) is the visceral fat layer located around the heart and is believed to be important for the buffering of the coronary arteries, and in providing fatty acids as a source of energy for the cardiac muscle. In man, local warming of the thoracic spinal cord and sympathetic ganglia would be done by paravertebral BAT and putatively by nearby intercostal arteries as they give off spinal branches that anastomose with the anterior spinal cord artery (14). In conclusion, the distribution of human BAT along the vasculature and around critical organs putatively confers survival value by hypothermia-induced adaptive thermogenesis, thereby preserving normal body temperature and, in turn, vital functions (26). [52]. Influence of adipose-cell size and site of adipose tissue on triacylglycerol formation in lean and obese rats,”, M. Palou, T. Priego, J. Sánchez, A. M. Rodríguez, A. Palou, and C. Picó, “Gene expression patterns in visceral and subcutaneous adipose depots in rats are linked to their morphologic features,”, M. Palou, J. Sánchez, T. Priego, A. M. Rodríguez, C. Picó, and A. Palou, “Regional differences in the expression of genes involved in lipid metabolism in adipose tissue in response to short- and medium-term fasting and refeeding,”, K. Frayn, “Adipose tissue as a buffer for daily lipid flux,”, D. E. Kelley, F. L. Thaete, F. Troost, T. Huwe, and B. H. Goodpaster, “Subdivisions of subcutaneous abdominal adipose tissue and insulin resistance,”, S. R. Smith, J. C. Lovejoy, F. Greenway et al., “Contributions of total body fat, abdominal subcutaneous adipose tissue compartments, and visceral adipose tissue to the metabolic complications of obesity,”, Y. Miyazaki, L. Glass, C. Triplitt, E. Wajcberg, L. J. Mandarino, and R. A. DeFronzo, “Abdominal fat distribution and peripheral and hepatic insulin resistance in type 2 diabetes mellitus,”, G. E. Walker, B. Verti, P. Marzullo et al., “Deep subcutaneous adipose tissue: a distinct abdominal adipose depot,”, M. Cnop, M. J. Landchild, J. Vidal et al., “The concurrent accumulation of intra-abdominal and subcutaneous fat explains the association between insulin resistance and plasma leptin concentrations: distinct metabolic effects of two fat compartments,”, K. Kadowaki, K. Fukino, E. Negishi, and K. Ueno, “Sex differences in PPAR, K. N. Manolopoulos, F. Karpe, and K. N. Frayn, “Gluteofemoral body fat as a determinant of metabolic health,”, M. B. Snijder, M. Visser, J. M. Dekker et al., “Low subcutaneous thigh fat is a risk factor for unfavourable glucose and lipid levels, independently of high abdominal fat.