Exercise changes fat in the body - compelling new hormonal evidence for running!

Researchers from Harvard Medical School & the Dana-Farber Cancer Institute have shown that exercise can produce a hormone in the body that can lessen the susceptibility to obesity and diabetes and other health issues.

Mouse & human muscle tissue was tested, with the scientists charting how muscles cells can communicate with other cells in the body  - particularly fat cells - and alter the biochemistry of the body after exercising.

PGC1-Alpha is produced in muscles both during and after exercise. It appears that this is what produces many of the benefits of exercise, but it was the Harvard study group that identified a novel process occuring to a membrane protein known as Fndc5 which spikes in expression with this increase in PCG1-Alpha. The protein breaks apart, and the novelty turned out to be a previously unidentified hormone which is secreted as Irisin. 

LV = Lipid Vacuole

This hormone acts on white adipose (fat) cells, turning a development of brown-fat-like cells. Brown fat is  more physiologically desirable than inert white fat calls, as they require energy & use oxygen:  they burn calories! That this also happens to the deep fat around the organs is also important in health. Until 2009, the assumed logic was that brown fat was in far greater quantities in babies than adults, but now it appears that irisin (potentially exercise-induced irisin) can be seen in older humans. 

Brown Fat Cell

Furthermore, rodent studies that have shown that irisin injected into white fat cells do indeed turn brown, and that glucose-tolerance was improved despite a high-fat diet. Human study participants whom volunteered for a jogging programme demonstrated higher levels of irisin after the programme finished than beforehand.

In summary, Irisin is thus induced with exercise and is shown in both mice & humans. Even mildly increased irisin blood hormone levels can cause an increase in energy expenditure with no associated changes in movement or food intake. This results in improvements in obesity & appears also to maintain glucose homeostasis with the implications for diabetes in humans.


Key message? Physical activity increases irisin levels in healthy people & changes fat cells from white to brown as a result. 
Exercise: All Good!


Here are some details:

A PGC1-α-dependent myokine that drives brown-fat-like development of white fat and thermogenesis

• Pontus Boström,
• Jun Wu,
• Mark P. Jedrychowski,
• Anisha Korde,
• Li Ye,
• James C. Lo,
• Kyle A. Rasbach,
• Elisabeth Almer Boström,
• Jang Hyun Choi,
• Jonathan Z. Long,
• Shingo Kajimura,
• Maria Cristina Zingaretti,
• Birgitte F. Vind,
• Hua Tu,
• Saverio Cinti,
• Kurt Højlund,
• Steven P. Gygi
• & Bruce M. Spiegelman

• Affiliations
• Contributions
• Corresponding author

Nature

 

(2012)

 

doi:10.1038/nature10777

Received

 

14 August 2011 

Accepted

 

13 December 2011 

Published online

 

11 January 2012