Obesity and Heating Trends (HOT)

Heating and Obesity Trends (HOT) is a research project based on a collaboration between the Bartlett and UCL's Epidemiology and Public Health. Funded by UCL's Crucible Centre, the study aimed to carry out a multidisciplinary literature review on obesity and temperatures, and a preliminary database search, with a view to establish whether greater indoor temperatures could contribute to weight gain. The UCL Crucible Centre is part of the cross-council Lifelong Health and Wellbeing Initiative. It has been suggested that the rise in indoor temperatures resulting from central heating, cheap fuel prices and energy efficiency in buildings could be a possible contributor to the secular increase in obesity.

This is because there is some evidence that remaining in the thermo-neutral zone promotes adiposity (Keith et al., 2006). Although this hypothesis has some biological plausibility, further research is needed in order to assess whether “comfortable” indoor temperatures may be a risk factor for obesity. For example, a number of studies have demonstrated that ambient temperatures can have an impact on metabolism and food intake.

However, several studies also showed a variability in cold-induced non-shivering thermo-genesis, which is linked to factors such as ambient temperature and cooling medium (water versus air), as well as to individual factors such as: body composition, age, gender, physical fitness, adaptation/acclimatisation, genetics, and diet. In addition, laboratories studies on mice and humans suggest that cold-induced metabolism is greater in lean subjects than in overweight ones, and that cold-induced metabolism may be partly counterbalanced by a greater food intake at low temperatures. 

The impact of ambient temperatures on weight gain is a complex phenomenon which has been addressed – explicitly or implicitly – in several studies within different disciplines. This project aims to carry out a multidisciplinary literature review on obesity and temperatures, which will address several aspects, such as: changes in indoor climates over time and data on the coincidence of warmer ambient temperatures and increased obesity, in different geographies and populations; laboratory experiments on human and animals, as well as veterinary studies on rearing.

People

PI: Marcella Ucci

Co-Is: Alexi Marmot and Jane Wardle (UCL Epidemiology and Public Health) 

Rs: Anna Mavrogianni and Fiona Johnson (UCL Epidemiology and Public Health) 

Output

The project resulted in two publications: 

Could increased time spent in a thermal comfort zone contribute to population increases in obesity?, Obesity Reviews, 2011 Historic Variations in Winter Indoor Domestic Temperatures and Potential Implications for Body Weight Gain, Indoor and Built Environment, 2011 

Impact

The publication published in Obesity Reviews was widely cited in 12 papers. Members of the team (Fiona Johnson and Marcella Ucci) presented the results of the project and its implications at a meeting with scientific advisors within DECC (Department Energy and Climate Change) on the 20th Apr 2011.