Thermogenesis is a particular metabolic process that consists in the production of heat by the body, especially in adipose and muscle tissue.
Metabolism, and therefore also the extent of thermogenesis, depends among other things on genetic factors and can therefore vary from individual to individual. These factors also influence the amount of so-called brown adipose tissue (brown fat), tissue capable of producing heat and energy by “burning” fat in greater quantities than any other part of the body.
Since body weight is determined by the balance between calories introduced with food and those burned with physical activity and with the various metabolic processes such as digestion, respiration etc., by stimulating thermogenesis it is possible to obtain a certain control of body weight.
All biological processes in which heat production takes place are defined thermogenetic. Heat is produced by the transformation of energy for oxidative or catabolic processes.
There are various types of thermogenesis and one of the most interesting is postprandial thermogenesis, that is, food-induced heat production. It can be measured mainly by indirect calorimetry, which is able to determine from the air exhaled by an individual, how many carbohydrates or lipids or proteins are burned per kg of body weight per minute. These parameters can be very useful to establish which are the variations of energy expenditure and which nutrients are preferentially used, in particular to draw up an appropriate diet. The energy expenditure in 24 hours consists of several components: the basal metabolic rate, related to sex and amount of muscle mass, thermogenesis and energy expenditure for physical exercise. The main determinant of energy consumption is the muscle and the diet influences the amount of lean mass and fat mass of the body. Therefore to establish an adequate diet should always be measured first not only the weight of muscle and fat, which is not easy, but also the amount of physical activity practiced.
Another type of thermogenesis is the regulation of the so-called “futile cycles”, i.e. the coupling of anabolic and catabolic processes (for example lipolysis and lipogenesis) and, perhaps most importantly, the use of thermogenin. Already mentioned previously in brown adipose tissue, this is a decoupling enzyme and is responsible for converting energy forfeited from the proton flux of oxidative phosphorylation (normally used to produce ATP) into heat.