Exercise changes the expression of a person's DNA in such a way that it alters the way fat is stored, according to researchers from Lund University in Sweden. The study is the first to describe what happens on an epigenetic level in fat cells when individuals participate in even small doses of exercise.

"Our study shows the positive effects of exercise, because the epigenetic pattern of genes that affect fat storage in the body changes," Charlotte Ling, associate professor at Lund University Diabetes Center, said in a press release.

While one's genes cannot be changed, attached to them are methyl groups that affect gene expression, or whether the genes are activated or deactivated. The methyl groups can be influenced in various ways, including exercise, diet and lifestyle. However, the field of study of these changes, called epigenetics, is relatively new with little understood when it comes to how these changes, called DNA methylation, occur.

In this particular study, the researchers investigated what happened to the methyl groups in the fat cells of 23 slightly overweight men all around 35 years old, none of whom had previously engaged in any physical activity, when they regularly attended spinning and aerobics classes over a six-month period.

"They were supposed to attend three sessions a week, but they went on average 1.8 times," Tina Rönn, associate researcher at Lund University, explained.

Nevertheless, using technology capable of analyzing 480,000 positions throughout the genome, researchers were able to identify epigenetic changes in 7,000 genes - roughly a third of a person's total genes. They then looked specifically at the methylation in genes linked to type 2 diabetes and obesity.

"We found changes in those genes too, which suggests that altered DNA methylation as a result of physical activity could be one of the mechanisms of how these genes affect the risk of disease," Rönn said, adding that, as a result of the first-of-its kind study, scientists now have a map of the DNA methylome in fat.

Back in the lab, the researchers were able to confirm the findings in-vitro by deactivating certain genes and thus reducing their expression. Sure enough, this resulted in changes in fat storage in fat cells.