A newly discovered hormone produced in response to exercise may indirectly help the body fight obesity and diabetes, according to a study published in “Nature”  this month.

Even though we might not lose significant weight with exercise,  we will still be healthier.

The study, reported on in The New York Times Jan. 13, shows how amazingly complex body systems are.  Since the hormone is exactly the same structure in both mice and humans, that suggests it is biologically very important – so much so that it has been preserved unchanged through eons of mammalian evolution.

Exercise, scientists found, produces an biochemical trickle down effect:  1)exercise produces an abundance of a substance called PGC1-alpha, 2) that causes an increase in a protein called Fndc5, 3)which breaks into parts, one of which is a newly identified hormone recently named “irisin,” 4)which leaves the muscle cell and travels to fat cells via the bloodstream, where is initiates  a process of changing regular white fat to brown fat.

Until recently, it was thought that only babies had brown fat.  Unlike white fat, which basically just sits there as a calorie storehouse, brown fat is metabolically active and uses oxygen and burns calories.

Mice bred to produce large amounts of PGC1-alpha in their muscles are typically resistant to age-related obesity and diabetes, much as people who regularly exercise are.

Now, when we say “Exercise is good for you,” we can fill in a few more of those mysterious gaps in our knowledge on why that may be so.