The conversion of white adipose tissue (WAT) to beige fat as a biological response to cold temperatures may be hindered in overweight individuals, according to a new study published online in the Journal of Clinical Endocrinology & Metabolism.
Philip A. Kern, MD, of the University of Kentucky School of Medicine in Lexington, KY, and colleagues recruited 55 subjects to investigate the role of temperature on WAT, particularly in increasing brown adipocytes in WAT depots and creating what is known as “beige fat.” Both beige and brown fat have been shown to burn calories and glucose to generate heat when exposed to cold temperatures. Subcutaneous WAT was examined in an abdominal group and thigh group during biopsies in “Winter” (between December 1 and March 21, with mean daily temperatures of 4–8 degrees Celsius) and “Summer” (June 1 to September 16, with mean daily temperatures of 20–24 degrees Celsius). The biopsies were compared to a control group of 16 healthy subjects.
The abdominal fat obtained via biopsy in “Winter” had higher levels of two genetic markers for beige fat vs. samples taken in “Summer.” In the thigh tissue group, elevated levels of three genetic markers tied to beige or brown fat were found in the “Winter” vs. summer samples. However, this difference was not statistically significant in patients with body mass index (BMI) >30, indicating that the response was blunted in obese individuals.
The authors believe that inflammation in obesity may hinder the conversion of WAT to beige fat during exposure to colder temperatures. This could have implications in further understanding of the role of BAT, seasonal changes, and weight management, they also added.
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