Natural "exercise" hormone transforms fat cells
Exercise makes cells burn extra energy—that's one way it helps control weight. It also generates a newly discovered hormone, called irisin, that transforms energy-storing white fat cells into energy-burning brown fat cells. Irisin also appears to help prevent or overcome cellular changes that lead to type 2 diabetes.
"Irisin travels throughout the body in the blood and alters fat cells," explains Dr. Anthony Komaroff, editor in chief of the Harvard Health Letter, in the June 2012 issue. "If your goal is to lose weight, you want to increase the number of brown fat cells and decrease white fat cells."
Fat "color" makes a difference
White adipose tissue, more commonly known as body fat, is the tissue that dimples thighs, enlarges waists and derrieres, and pads internal organs. Each white fat cell stores a large droplet of fat. Brown fat, in comparison, is chock full of energy-burning mitochondria. Its main function is to generate body heat by burning fat.
Babies are born with brown fat, but it was thought to gradually disappear. In 2009, several studies showed that adults still have brown fat cells lurking in their bodies. Earlier this year, a team led by Dr. Bruce Spiegelman, professor of cell biology and medicine at Harvard Medical School, identified irisin in mice and humans. His team also showed how irisin transforms white fat cells into brown ones, at least in mice. The same thing is likely to happen in humans, too, but that remains to be worked out.
This transformation helps the body burn more energy during exercise. The effect lingers, since brown fat cells keep burning fat even after you've stopped exercising. In addition, Spiegelman's work showed that irisin also helps prevent or overcome insulin resistance, which leads to type 2 diabetes.
No need to wait
The possibility of creating a new medication based on irisin for weight loss or type 2 diabetes may have pharmaceutical companies already mapping out the long, expensive process for bringing a new drug to market. But you can make your own irisin today, for free, by exercising. And even if irisin's effects aren't quite as potent in humans as they are in mice, you are still getting all the other benefits that exercise has to offer.
What can improve your mood, boost your ability to fend off infection, and lower your risk for heart disease, diabetes, high blood pressure, and colon cancer? The answer is regular exercise. It may seem too good to be true, but it's not. Hundreds of studies demonstrate that exercise helps you feel better and live longer. This report answers many important questions about physical activity. It will also help guide you through starting and maintaining an exercise program that suits your abilities and lifestyle. Learn more »
Successful weight loss depends largely on becoming more aware of your behaviors and starting to change them. Rather than willpower, this process demands skill power, which is good news because you can learn new skills. This report offers a range of solutions that have worked for many people and can be tailored to your specific needs. Take this challenge seriously, though, because overweight and obesity can lead to serious medical problems.Learn more »
Click here to read the full Harvard Health Letter article on irisin.
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.