Warmer winter temperatures within the homes of Americans, British and other countries’ could be a factor in the current obesity epidemic, researchers from London University College (UCL), England, wrote in Obesity Reviews. The authors had set out to find out whether there might be a causal link between less exposure to winter temperatures and obesity in the USA and UK.

If the human body has less cold exposure during the winter time, the researchers suggest there may be two possible consequences on bodyweight:

  • There will be less need for burning energy to keep warm
  • The body’s capacity to produce heat may go down.

The journal’s review summarizes evidence for increases in winter indoor temperatures in the USA and UK and also looks at the biological plausibility of the theory that exposure to winter could help regulate energy balance and body weight.

Over the last few decades, not only have houses in the UK and USA have become much warmer, but most of them are set at similar temperatures.

As people take winter warmth for granted, most individuals are being exposed to the cold at ever decreasing rates. In short, in the USA and UK most of us are experiencing milder temperatures than before.

The researchers write about brown fat (brown adipose tissue), and its role in heat production in human beings. Brown fat can burn energy to create heat, unlike white fat. Scientists believe we produce brown fat in response to environmentally cold temperatures. The longer we are in warm environments, the more brown fat we lose, and consequently our capacity to burn energy, some recent studies have suggested.

Lead author Dr Fiona Johnson, said:

“Increased time spent indoors, widespread access to central heating and air conditioning, and increased expectations of thermal comfort all contribute to restricting the range of temperatures we experience in daily life and reduce the time our bodies spend under mild thermal stress – meaning we’re burning less energy. This could have an impact on energy balance and ultimately have an impact on body weight and obesity.

Research into the environmental drivers behind obesity, rather then the genetic ones, has tended to focus on diet and exercise – which are undoubtedly the major contributors. However, it is possible that other environmental factors, such as winter indoor temperatures, may also have a contributing role. This research therefore raises the possibility for new public health strategies to address the obesity epidemic.”

Co-author, Marcella Ucci , said:

“The findings suggest that lower winter temperatures in buildings might contribute to tackling obesity as well reducing carbon emissions.”

“Could increased time spent in a thermal comfort zone contribute to population increases in obesity?”
F. Johnson, A. Mavroggiani, M. Ucci, A. Vidal-Puig, J. Wardle
Obesity Reviews DOI: 10.1111/j.1467-789X.2010.00851.x

Written by Christian Nordqvist