In the first study of its kind on fat tissue and fat cells, researchers at the University of Florida have discovered that an exercise-induced hormone, irisin (also known as FNDC5), is a fat-fighting powerhouse. The results provide a new source of motivation for exercising more or losing some weight and keeping it off.

Irisin is called the “exercise hormone” colloquially because it's released during moderate aerobic endurance activity when your cardiorespiratory system is engaged and your muscles are exerted.

The groundbreaking study shows that irisin fights fat with a one-two punch. First, irisin appears to activate genes and a protein that transform calorie-storing white fat cells into brown fat cells—which continue to burn energy after you finish exercising. Second, irisin appears to inhibit the formation of fatty tissue.

The September 2016 report was published this week in the American Journal of Physiology - Endocrinology And Metabolism. This study affirms that stimulating the production of irisin via exercise is a beneficial clinical intervention for maintaining healthy body weight and combating obesity. This research was led by Li-Jun Yang, professor of hematopathology in the UF College of Medicine’s department of pathology, immunology, and laboratory medicine.

For this study, Yang et al. collected fat cells from 28 patients who had undergone breast reduction surgery. After exposing the fat cells to irisin, they found a nearly fivefold increase in cells that contain a protein known as UCP1. This protein is essential for fat "burning" to occur. In a statement to University of Florida, Yang said,

"We used human fat tissue cultures to prove that irisin has a positive effect by turning white fat into brown fat and that it increases the body's fat-burning ability. The findings about irisin's role in regulating fat cells sheds more light on how working out helps people stay slender.

Instead of waiting for a miracle drug, you can help yourself by changing your lifestyle. Exercise produces more irisin, which has many beneficial effects including fat reduction, stronger bones, and better cardiovascular health.”

Yang and her collaborators found that irisin literally suppresses fat-cell formation. When they tested fat tissue samples of an exercise group to a sedentary control group, they found that irisin reduced the number of mature fat cells by a staggering 20 to 60 percent.

The researchers believe that irisin is reducing the storage of fat in the body through a complex chain reaction that hinders a process by which undifferentiated stem cells are turned into fat cells. Irisin also appears to simultaneously promote stem cells' differentiation into bone-forming cells.