Cold temperatures can help shed weight, according to a University of Kentucky study.
The researchers said that exposure to such harsh temperatures converts white fat tissue from the thighs and belly to beige fat that burns calories for heat. However, this biological response is disrupted in obese people.
Brown adipose tissue (BAT) or brown fat burns energy and glucose to generate heat. This fat helps babies and small animals to stay warm. Brown fat's energy expenditure prevents obesity in rodents. When white fat essays the role of brown fat, the tissue created in this process is called beige fat.
"We wanted to investigate whether human adults had the ability to transform some white fat deposits into beige fat when they were exposed to cold," said one of the study's authors, Philip A. Kern, of the University of Kentucky School of Medicine. "Browning fat tissue would be an excellent defense against obesity. It would result in the body burning extra calories rather than converting them into additional fat tissue."
For the study, the researchers examined belly fat tissue samples from 55 people to determine browning activity levels in summer and winter. They also collected thigh fat tissue samples from 16 people after they placed an ice pack on the skin for 30 minutes.
The researchers found that belly fat and thigh tissue samples taken during winters had more genetic markers for beige fat than those taken in the summertime. They also found that white fat browning mechanism was blunted in obese people.
"Our findings indicate inflammation can hinder the conversion of white to beige fat," Kern said. "When we analyzed tissue samples in the lab, we found that exposing white fat to macrophage cells from the immune system inhibited the transformation."
The finding is published in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism.
