White adipose tissue (WAT) expansion is related to the development of metabolic disorders found in obesity. WAT expansion is the result of generation of new adipose cells by activation of adipogenesis and/or the increase in adipose cell size (hypertrophy). The balance between these two processes determines whether WAT expansion occurs predominantly by hyperplasia, which means the increase in the number of adipocytes, or hypertrophy. Hypertrophic adipocytes are characterized by changes in adipokine secretion pattern, insulin resistance and altered lipid metabolism, which is the reason why WAT-hypertrophic expansion is considered unhealthy. Conversely, the generation of new mature adipocytes by adipogenesis contributes to reduction of the development of hypertrophic adipocytes and therefore maintain normal WAT functions, leading to healthy hyperplastic expansion. The adipogenic capacity of adipose tissue depends on the adipogenic potential and the number of adipocyte precursor cells. Different factors are known to regulate adipogenic process and adipose tissue function, contributing to a healthy or unhealthy expansion that occurs under positive energy balance. This chapter discusses the role of fructose intake and glucocorticoids and testosterone as regulators of adipose tissue function and expansion.
Part of the book: Adiposity