Obesity develops when caloric intake exceeds energy expenditure; the difference in these values determines the change in your weight. Dieting reduces the intake variable, while exercise increases our expenditure of energy. Research into the relationship between obesity and the process of thermogenesis has revealed important insights into our understanding of heat regulation and weight loss.
Thermogenesis
Also known as heat production, thermogenesis is an essential process in all warm-blooded animals, and there are many ways for your body to produce heat. Exercise involves the intentional contraction of muscles, producing locomotion through the coordinated action of opposing muscle groups. Alternatively, the process of shivering involves subconscious, antagonistic muscle contraction, which produces heat through a similar mechanism. However, there are also specialized types of fat tissue capable of generating heat without movement.
Brown and White Fat Cells
There are two types of fat cells in your body: brown and white. Also known as adipocytes, these two forms of fat tissue carry out very different functions. White adipose tissue, which is what most of us think of when we imagine fat, is involved in energy storage. White adipose tissue is the type that contributes most to obesity. Brown adipose tissue, however, is involved in the process of thermogenesis and aids in energy expenditure. Until recently, it was believed that only children possess brown fat. However, recent research from the Joslin Diabetes Center reports that adults also have functional brown fat cells, which continue to play a role in energy balance even after childhood.
Brown Adipose Tissue Thermogenesis
Research into how energy expenditure is regulated by brown fat cells is vital to our understanding of temperature regulation and fat breakdown. Studies from the University of Ottawa have reported on the control of gene expression in brown adipose tissue, demonstrating the importance of specific proteins located in the mitochondria. Also known as the powerhouse of the cell, the mitochondria is responsible for converting fats and other fuel sources into more accessible forms of energy, specifically ATP. Brown fat cells produce proteins that create an energy leak from the mitochondria. As a result, heat will dissipate out of these cells rather than being stored as ATP. This process requires the breakdown of fat molecules and is used by your body to generate its own heat when necessary.
Obesity Therapy
A 2010 article from Harvard Medical School describes developing obesity therapies that could potentially harness the power of brown fat cell thermogenesis to produce weight loss. While most current obesity treatments focus on reducing caloric intake, this approach would increase the expenditure of energy at the cellular level. By increasing the amount of heat generated by brown fat and skeletal muscle mitochondria, excess fat molecules could be dissipated through this alternative mechanism.
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