Scientists have some chilling news for those using heaters at home - keeping our homes cosy actually prevents us from burning up calories to warm up our bodies. Modern centrally-heated homes with efficient double glazing are helping to send obesity rates soaring, says a University College London study. It is an increasing problem across the developed world where average indoor temperatures are constantly rising, the journal Obesity Reviews reports. Fiona Johnson, who led the study at Oxford, said: "Increased time spent indoors, widespread access to central heating and air conditioning, all contribute to restricting the range of temperatures we experience in daily life." And its impact on weight is made worse by the extra time we now spend indoors, whether working from home or shopping online, according to the Daily Mail. Even when we do venture out, it is often via heated cars or other transport to offices and workplaces where the temperature is carefully controlled by air conditioning units. The research said there was a direct link between "reduced exposure to seasonal cold and increases in obesity in the UK and US." If the body is already warm, it does not need to convert a 'brown' fat known as adipose tissue into energy to generate heat, the study said. Brown fat was previously thought to be present only in infants, playing a vital role in keeping them warm, but recent research found it in adults as well. This latest study suggested that prolonged exposure to comfortable warm temperatures may permanently reduce the body's ability to burn this brown fat.