Irisin: a hormone that might help losing weight without hard exercise

A team of medical scientists, led by a cell biologist from Dana-Farber Cancer Institute in Boston, Bruce M. Spiegelman, discovered a hormone, called irisin, that appears to increase fat burning and to improve glucose homeostasis.

These findings might play a great role in fighting obesity and controlling hypertension and type 2 diabetes.

The study was published this month in Nature, International weekly journal of science.

Irisin is produced by muscles during the exercise and has the ability to convert white adipose cells into a brown-fat-like development.

“It has powerful effects on the browning of certain white adipose tissues,” cell cultures as well as in living animals, the researchers wrote.

The white fat is the “bad fat” that makes the belly look unaesthetic, and, worse, can clog the arteries leading to heart attack or stroke. Brown fat is the “good fat” that can easy be transformed in energy, leaving no trace. Brown fat can be found in young mammals, as well as in children. As you grow older, the brown adipose cells diminish.

“We knew the effect wasn’t only limited to muscle,” said Pontus Bostrom, cell biologist at Harvard and member of the team.

“There has been a sensation in the field that work out ‘talks to’ various tissues in the human body. But the problem has been, how?” said Bruce Spiegelman.

Researchers found out that exercise can increase the expression of a membrane protein (FNDC5) from what irisin is produce.

They have studied mice that were let to do three weeks of free-wheel running. Irisin levels arised by 65 percent. In the persons who underwent ten weeks of “supervised endurance exercise training,” irisin levels doubled.

The team introduced into obese mice bodies (mice fed with a high-fat diet) viruses carrying a synthesized gene. This gene triggered a cascade of reactions leading to an increased secretion of irisin. Even a short course of FNDC5 and a small increase in irisin levels led to some weight loss. Fat burning increased like after exercising, growth hormone levels were elevated, blood sugar levels (glycemia) were lowered. Their muscles consumed more oxygen (burned more calories), their growing insulin resistance was reversed and their glucose tolerance was improved.

The medical scientists injected those mice with anti-FNDC5 antibodies to stop the secretion of irisin, and as a result after ten days of swim training they had the same weight.

 

 

Irisin seems to be a promising remedy for diabetes, obesity, and probably neurological disorders as Parkinsons.

“In the future, we hope to be able to give this as a therapeutic to treat metabolic diseases, but there’s a long road ahead,” said Pontus Bostrom.

The medical team wants to find out if long-term treatment with irisin can lead to more weight loss and control obesity-related conditions (hypertension, heart disease, diabetes).

“Whether long treatments with irisin an/or higher doses would cause more weight loss remains to be determined,” wrote the researchers.

However, even as a treatment or a dietary supplement, this hormone will be able to help a person to lose weight in an easier manner, but it cannot replace the exercise.

“The very last factor in the planet we’re striving to do is substitute for diet and workout,” said Spiegelman.

Regular exercise leads to improvements in metabolic function and other processes (such as inflammation) that obesity aggravates.

Irisin was named after the Greek messenger goddess, Iris, it is a way to say that this hormone carries a message of health throughout the body.