Exercise and you will shed weight and maintain the weight loss! Okay, so you have had your gym instructor, your aunt, your neighbour’s third cousin, your grandfather ánd your friends throw this nugget of wisdom at you. And you are probably tired of hearing it. Bear in mind, though, that this is not just a casual nag or a facile bit of wisdom. There is, naturally, a straightforward relationship between muscle movement and utilization of energy stored in body fat. However, there is more to the picture than this simple debit equation.
There are two distinct ways in which exercise can boost your metabolism and burn body fat even when the exercise session is over. In 2012, the discovery of Irisin, a molecule secreted by muscle cells indicated new pathways by which muscle cells can exert their influence on fat cells. Irisin is secreted by muscle cells and it exerts its effects on distantly located white adipose cells (also known as white fat cells).
White adipose cells are converted into brown adipose cells when they are exposed to Irisin. Brown adipose cells actively break down stored fat to generate body heat instead of energy (Sanchis-Gomar et al., 2012, Villarroya, 2012). This process, in turn, helps to deplete the stores of white fatty tissue. Brown adipose cells have a greater number of mitochondria (greater than white adipose cells) and these are engaged in burning fat to create heat and maintain body temperature.
Recent research has helped to identify another molecule secreted by muscle cells, β-isoaminobutyric acid (BAIBA) that works in a similar fashion (Roberts et al., 2014). BAIBA is secreted by muscle cells, following physical exercise, and it acts on white fat cells to convert them into brown fat cells. Under the influence of BAIBA, white adipose cells begin to express proteins that are involved in generation of heat. This leads to a conversion of white adipose cells into brown adipose cells. Additionally, the secretion of BAIBA and its subsequent action on fat cells also helps to increase sensitivity to insulin and reduce the risk of cardiovascular disease.
Let us say it again. Exercise and you will lose weight and remain thin!
Photo: Flickr, Living Fitness UK
ROBERTS, LEE D., BOSTRÖM, P., O’SULLIVAN, JOHN F., SCHINZEL, ROBERT T., LEWIS, GREGORY D., DEJAM, A., LEE, Y.-K., PALMA, MELINDAJ., CALHOUN, S., GEORGIADI, A., CHEN, M.-H., RAMACHANDRAN, VASAN S., LARSON, MARTIN G., BOUCHARD, C., RANKINEN, T., SOUZA, AMANDA L., CLISH, CLARYB., WANG, THOMAS J., ESTALL, JENNIFER L., SOUKAS, ALEXANDER A., COWAN, CHAD A., SPIEGELMAN, BRUCE M. & GERSZTEN, ROBERT E. 2014. β-Aminoisobutyric Acid Induces Browning of White Fat and Hepatic β-Oxidation and Is Inversely Correlated with Cardiometabolic Risk Factors. Cell Metabolism, 19, 96-108.
Sanchis-Gomar F, Lippi G, Mayero S, Perez-Quilis C, & García-Giménez JL (2012). Irisin: a new potential hormonal target for the treatment of obesity and type 2 diabetes. Journal of diabetes, 4 (3) PMID: 22372821
exercise, sports, body fat, reduce, molecule, Irisin, adipose, white, brown