Being Warm in Winter Favors Obesity

In winter, everybody does what they can to stay warm, and to make their home as comfortable as possible but it seems it is not such a good idea after all, because, according to a UCL research, the increases in winter indoor temperatures could be contributing to rises in obesity.

This review paper looks at evidence of a possible causal relationship between increases in obesity in the United States and the United Kingdom, and the reduced exposure to seasonal cold.

Being exposed to cold makes the body spend energy to stay warm and work its ability to produce heat, but when we reduce our exposure to cold, this could affect our body's ability to maintain a healthy weight.

The paper presents all the evidence that winter indoor temperatures are increasing both in the US and the UK, and also analyzes the idea that exposure to seasonal cold could regulate body weight and energy balance on a population level.

It looks like winter indoor temperatures have increased over the last few decades and the homogenization of temperatures in homes rose as well.

Furthermore, people would rather be comfortable during winter, so they decrease cold exposure and spend most their time in milder environments.

“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,” said lead author Dr Fiona Johnson, UCL Epidemiology & Public Health.

“This could have an impact on energy balance and ultimately have an impact on body weight and obesity.”

The authors also mentioned the role of the brown adipose tissue / brown fat in human heat production, and said that its development in the body is triggered by exposure to low temperatures.

Having brown fat is good because it has the ability to burn energy and create heat, but recent studies suggested that spending more time in warm conditions causes a loss of brown fat, thus a reduced capacity to burn energy.

Dr Johnson said that “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 , UCL Bartlett School of Graduate Studies, added that “the findings suggest that lower winter temperatures in buildings might contribute to tackling obesity as well reducing carbon emissions.”

The paper is published in the journal Obesity Reviews.