Our recent publication in the International Journal of Sports Medicine seeks to parallel and examine differences between the cellular and molecular effects of exercise with those of cold exposure on white and brown adipose tissue.
White adipose tissue is the storage form of fat, whereas brown adipose tissue is a thermogenic tissue whose uncoupling increases energy expenditure. Cold exposure is the most established activator of brown adipose tissue, which results in increases in sympathetic nervous activity and lipolysis as well as in the activation of numerous cellular and molecular pathways involved in brown adipose tissue, including upregulation of the BAT markers uncoupling protein 1 (UCP1) and proliferator-activated receptor gamma coactivator-1α (PGC-1α), as well as BAT activators, such as irisin, fibroblast growth factor-21 (FGF21), and atrial-and brain natriuretic peptides. The continuous beta-adrenergic stimulation that occurs from cold exposure can lead to the recruitment or conversion of brown adipocyte-like cells among white adipose tissue cells in a process referred to as "beiging." The prescription of exercise, a common nonpharmacological approach to weight loss, also increases sympathetic nervous activity, lipolysis, and secretion of hormones and adipokines, thereby eliciting similar effects to cold exposure.
As such, we conducted systematic literature searches for the impact of cold exposure and exercise on PGC-1α, FGF21, irisin, and atrial- and brain natriuretic peptides (ANP and BNP) in adipose tissue and for exercise on UCP1. We ultimately found that markers of brown adipose tissue activation increase from both cold exposure and exercise, whereas effects in white adipose tissue are compartment-specific. The stimulation of endocrine activators depends on numerous factors, including stimulus intensity and duration. While this evidence was demonstrated by increases in adipose activity in rodents, effects remain challenging to quantify in humans and should be experimentally examined in future research.
For more information, you will find the full-text here