Winter can help you lose weight but not if you are already obese.
Exposure to cold temperatures can convert white fat tissue from the thighs and belly to beige fat that burns calories for heat.
Unfortunately in people who are already very overweight this biological response is hampered.
Brown fat known as brown adipose tissue (BAT) is a particular kind of body fat that burns energy and glucose to generate heat.
Babies and small animals rely on brown fat to stay warm.
White fat does not have this ability.
It can play a role in burning calories but is not as efficient at doing so as brown fat.
Researchers at the University of Kentucky School of Medicine in Lexington analysed belly fat from 55 people to see if the samples taken in winter showed more evidence of brown fat than those taken in summer.
They also took thigh fat samples from 16 people after they had held an ice pack on the skin for half an hour.
The analysis showed belly fat in winter had a higher level of brown fat compared to summertime.
The thigh samples gave a similar result.
The researchers also found, however, that the response was blunted in obese people, that is those with a body mass index greater than 30.
The results are published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism