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Warming up the Issue of Heat Loss

July 15, 2016

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Obesity was classified as a disease by the American Medical Association in 2013, and has become a serious epidemic issue in many developed and developing countries. Global obesity levels have more than doubled since 1980, with more than 600 million adults classified as obese in 2014. It is commonly believed that carrying excessive body fat would help in isolating the body from low external temperatures. Understanding how body fat works to keep animals warm is particularly important for obesity researchers. A recent paper published in the American Journal of Physiology - Endocrinology and Metabolism is now challenging the common belief, showing that in preclinical models fur, rather than fat, ensures the body temperature is kept constant.

The greater availability of energy-dense, high-fat foods, coupled with the increased inactivity of the global population results in an energy imbalance between calories consumed and calories expended, which ultimately leads to weight gain and obesity.

Obesity can lead to several health problems, such as diabetes, cardiovascular diseases, obstructive sleep apnea, and certain types of cancer. Given its epidemic proportion it is crucial that we start to better understand the physiology of the disease.

Body fat, is commonly believed to have protective properties from cold temperature. The fat layer under the skin of animals adapted to live in the cold is generally considered to provide thermal insulation, preventing the dissipation of the body heat.

Human neonates and small animals use a special kind of fat called brown adipose tissue (BAT) to produce heat when their body temperature drops. Recently the presence of BAT tissue and its function as a thermo regulator has also been shown in adult humans.

What Happens When the Body Carries an Excess of Fat?

Researchers from Stockholm University in Sweden and the University Medical Center Hamburg-Eppendorf in Germany set out to understand whether there is any scientific evidence that an excess of body fat could prevent heat dissipation in small animals that were challenged with cold temperature. They reasoned that if this was the case, obese animals challenged with cold temperature would need to burn less calories to keep warm than their non-obese siblings.

The team conducted several experiments but found no evidence of body fat acting as an insulator. They found that, in small animals, fur plays a more prominent role than fat in keeping warm and they reasoned this could be due to the location of the storage fat in these models. In mice, like in humans, fat is accumulated centrally in the body, around organs, rather than under the skin.

These type of studies have never been rigorously conducted in humans, nonetheless, the general believe is that obese people are better insulated than lean people and this would tend to aggravate their obesity. Based on their results in small animal models the team is now challenging this view and they are further arguing that the human population is rarely challenged by the external temperature, given that housing where the temperature is artificially kept livable is widely available in developed countries, where obesity is on the rise.

Given the prevalence of obesity among the human population and the fatality of the disease complications it is crucial that more studies are conducted to understand, the precise molecular and cellular mechanisms of obesity and obesity-associated health problems. Appropriate preclinical technologies and models are required to further research and evaluate anti-obesity agents.

CrownBio provides a unique collection of models of spontaneous and diet-induced obesity, including conventional rodent models such as those utilized in the study discussed here, as well as unique, highly translatable obesity models (the FATZO mouse and the ZDSD rat) that more closely resemble the human disease, which depends on several genetic factors for its development. At CrownBio we also provide a unique collection of NHP that spontaneously develop obesity. These models have better pathophysiological similarities to humans, and provide important information relevant to human obesity.

CrownBio’s service offering for obesity research includes measurement of several parameters, including body fat/body composition, food consumption and energy expenditure. Our study protocols are completely customizable to meet the needs of our clients drug discovery programs.

Contact us today at for full details on our models and for access to more model information.

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