Grant: CIHR Fellowship

Brown fat is a specialized organ found in most mammals, whose primary function is to produce heat when exposed to the cold. Recently, however, this tissue has garnered some interest in humans as a potentially valuable target for the treatment of obesity and obesity-related complications since it may play an important role in burning extra calories. Recent studies have shown that brown fat can significantly contribute to energy expenditure when exposed to a mild cold, uses circulating glucose and fat as a fuel and is most often found in lean individuals and to be of a greater size than individuals with type 2 diabetes. Brown fat from subjects with type 2 diabetes utilize relatively less glucose per volume of tissue, have a smaller volume, but still appears to function normally during cold exposure. What has been clear to date, is this tissue also has the ability to grow in size or increase in its capacity through daily cold exposure. The purpose of this study is to examine whether: (1) the potential for this tissue to grow in size and capacity is possible in men with a glucose intolerance and (2) whether activating this tissue after ingesting a meal will lead to the ingested energy being stored or dissipated as heat. We anticipate that, following four weeks of daily cold exposure, the energy expended by brown fat following the ingestion of the meal will be increased and that it will take up a significant amount of the fat derived from this meal. We expect that these changes will be improved but to a lesser extent in men with a glucose intolerance. The results of these studies should provide a definitive answer to the long-debated role of brown fat in utilizing food-derived energy and is essential to establish brown fat activation as a viable preventive and therapeutic target for type 2 diabetes.