Scientists fear rising energy bills may lead to an increase in obesity after discovering a link between poorly-heated homes and higher body fat.
Researchers from the University of Stirling's Behavioural Science Centre set out to explore claims that warm indoor temperatures have contributed to rising obesity levels in winter.
Instead, the team found that people who live in well-heated homes are more likely to have low body mass index (BMI) levels while those who keep their heating turned down or off tend to be heavier.
Dr Michael Daly, behavioural scientist and senior lecturer, said: "We set out to investigate the scientific claims that cooler indoor temperatures help us maintain a healthy weight by pushing our bodies to expend more energy through shivering and generating heat through tissues.
"In fact, the research suggests people may eat less and burn more energy when residing in a warmer indoor environment."
The 13-year study, published in the journal Obesity, involved more than 100,000 adults across England.
Researchers found reduced weight levels among people living in homes heated to above 23C (73F), which accounted for about 15,000 of the households studied.
Dr Daly said: "As national gas bills continue to rise faster than the rate of inflation, this research suggests the obesity epidemic could worsen where heating is turned down below comfortable levels or off for lengthy periods to cut costs.
"This is not just about people who live in well-heated homes being in the financial position to afford more expensive low-calorie foods, exercise classes and sporting activities, and therefore finding it easier to maintain a low BMI level. The study took age, gender, social class and other factors into account.
"The comfortable ambient temperature of 20.3-23C is where we feel comfortable in our clothes and are neither hot nor cold. At temperatures above this, we expend more energy and we eat less because our appetite is suppressed."