Exposure to cold temperatures can convert white fat tissue from the thighs and belly to beige fat that burns calories for heat, says new research.

Known as brown adipose tissue (BAT), brown fat is a kind of fat tissue that burns energy and glucose to generate heat.

White fat does not have this ability but plays a role in burning calories when it takes on some brown fat characteristics and the tissue created in this process is called beige fat.

In lab settings, when rodents were exposed to cold temperatures, they converted 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 Philip A. Kern at University of Kentucky's school of Medicine in Lexington.

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, Philip pointed out.

Researchers analysed belly fat tissue samples from 55 people to see if the tissue samples taken in winter showed more evidence of browning activity than those taken in summer.

"Our findings indicate inflammation can hinder the conversion of white to beige fat," stressed Kern.

When researchers analysed tissue samples in the lab, they found that exposing white fat to macrophage cells from the immune system inhibited the transformation.

The study appeared in the Journal of Clinical Endocrinology & Metabolism.