Exposure to Cold Climate Boosts Weight Loss, Study

A team of researchers has discovered that exposure to cold temperatures facilitates weight loss.

In the study led by researchers at the University of Kentucky School of Medicine, it has been found that regular exposure to cold temperatures help convert the white fat tissue from the regions of thigh and belly to beige fat that burns down the calories for heat. But, in obese people this biological mechanism is hampered.

Brown fat, also known as brown adipose tissue, is a kind of fat tissue that burns energy as well as glucose to produce heat. It is this brown fat that helps babies and small animals stay warm. The energy spent by the brown fat helps prevent obesity in rodents. On the other hand, this ability is absent in the white fat; rather, it plays a key role in burning calories when it takes on some characteristics of the brown fat.

During this process, the tissue that is created is called beige fat. On exposing the rodents to cold temperatures, they converted the white fat deposits to 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, MD, of the University of Kentucky School of Medicine in Lexington, KY. "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."

In this study, the researchers analyzed the samples of belly fat tissue in 55 people to verify if the tissue samples taken in winter displayed the evidence of browning activity than those taken in summer. Apart from this, samples of fat tissue were taken from the thigh of 16 people after they held a pack of ice on the skin for nearly 30 minutes. They checked for the tissue samples for specific genetic markers present in brown or beige fat.

The analysis showed that belly fat tissue biopsied in the winter contained higher levels of two genetic markers of beige fat than the samples retrieved during summertime. In the thigh tissue samples, the researchers noticed that high levels of three genetic markers tied to beige or brown fat in samples taken during winter.

They even analyzed the belly fat samples to check whether any difference existed in response among lean and obese people. The analysis showed that the seasonal effect of brown fat browning was not evident in the obese people. Obese people are those with body mass index of more than 30.

"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 was documented in the Journal of Clinical Endocrinology & Metabolism.