Here’s one more reason get up from your sofa and take that spin class at your gym: New research shows that working out helps prevent your body from producing fat cells and generates healthy bone cells instead.

The research sheds some light as to why exercise has such a positive and powerful effect on your body (aside from helping you look hot in your favorite slinky dress). In the study, published by the Journal of the Federation of American Societies for Experimental Biology, mice were either sedentary or ran on a (presumably mice-size) treadmill for less than an hour three times a week. Researchers at McMaster University in Ontario, Canada, found that the aerobic exercise triggered the mice’s stem cells to become bone more often than fat. In sedentary mice, the same stem cells were more likely to turn into fat.

QUIZ: How Much Exercise Do You Get?

If it’s been a while since you were in science class, here’s a quick stem cells primer: Stem cells have a unique ability to give rise to all sorts of tissues throughout your body—from brain cells to muscle cells to red blood cells. Certain type of adult stem cells, called mesenchymal stem cells, can morph into bone cells (osteocytes) or fat cells (adipocytes), as well as cartilage and connective tissue cells such as those in tendons.The research revealed that moderate exercise helps influence those mesenchymal stem cells to become bone rather than fat, boosting your overall health.

COLUMN: Exercise Basics from Fitness Expert Tracy Hafen