This week at morning report, Dr. Biff Palmer who is a professor of internal medicine at UT Southwestern in the nephrology division, talked with the housestaff about recent research that has shed light on brown adipose tissue and “beige cells” and their role in metabolism and weight loss. This has gained recent coverage in the media, which many news services have referred to as the “polar vortex diet”. But is there any actual science to this?
YES! Long story short, brown adipose tissue in adults is associated with weight loss as it takes calories from normal fat and burns it. Brown fat plays a key role in thermogenesis and has been a target for weight loss. Scientists have shown that with cold exposure, brown adipose tissue become more metabolically active and may potentially lead to weight loss. White adipose tissue on the other hand functions to store energy as scientists have looked for ways to convert white adipose tissue to brown to enhance metabolism and weight loss. Thus, a third subtype of adipose tissue has been identified called “beige adipocytes” which are white fat cells that express similar genes as brown fat cells, particularly under cold exposure and beta-adrenergic stimulation, and may lead to weight loss. Dr. Ajay Chawla from UCSF recently published a paper in Cell, determining that interleukin 4 and interleukin 13 recruit macrophages to fat leading to catecholamine production and the browning of white fat in mouse models. Studies like this has made this an active area of research for potential targets to treat obesity and maintain weight.
Dr. Palmer recently co-authored a paper looking at the effect of Roux-en-Y gastric bypass on browning in gonadal adipose tissue of female mice and may help offer further insight as to why this surgery leads to weight loss and remediation of type-2-diabetes.The study showed that upregulation of Nppb, Npr1, Npr2, and Beta-3 adrenergic receptors in gonadal adipose tissue following RYGB was associated with increased browning which may lead to those beneficial effects. Check out the study co-authored by Dr. Palmer below as well as a great summary about brown and beige fat cells by Nature by clicking on the links below!
Brown and beige fat: development, function, and therapeutic potential (Nature Medicine)
Photo (AP Photo/Mark Lennihan)