It turns out that you aren't just what you eat -- you're also "what you do," according to Juleen Zierath, professor of clinical integrative physiology at the Karolinska Institutet in Sweden.
Zierath and colleagues recently found that healthy, but inactive young adults experienced an immediate change to their muscle cells' genetic material when they engaged in just a few moments of exercise on a stationary bicycle.
Specifically, samples of thigh muscle from the study participants had fewer markers of methyl-group chemicals after exercise than they did before it. Those methyl groups, in turn, are used to moderate genetic expression. The changes were seen specifically in areas that affect genes responsible for energy metabolism -- by contrast, areas that were unrelated to metabolism had steady levels of methyl group chemicals. What's more, the harder the brief workout, the more demethylized the metabolism-related regions became.
The genetic changes that occur from exercise are happening in the epigenome, which is responsible for the expression of genes. While we inherit our genetic code from our parents, environmental factors like lifestyle play a large role in whether or not a gene is "turned on" so that its function can be expressed. As HuffPost blogger Dr. Frank Lipman recently explained:
The epigenome changes in response to signals. Signals come from inside the cell, from neighboring cells or from the outside world.
It is through the epigenome that environmental factors like diet, stress and prenatal nutrition can make an imprint on genes that pass from one generation to the next. Bottom line: While each of us inherits our own unique, hardwired, unchangeable version of the genetic code, epigenetic factors such as lifestyle and diet can radically change what our genes do.
In the specific case of exercise, researchers theorized that muscle contractions could be what's stimulating the demethylization. They performed a secondary experiment in which they exposed rodent muscle cells directly to caffeine, which causes a chemical reaction that mimics muscle contraction. They found that the cells had similar demethylation as the live, human study participants' muscle cells. Does that mean a cup of coffee will bring the same metabolic change? Chances are slim. “One would need to consume a caffeine equivalent of about 50 cups per day, almost close to a lethal dose”, Zierath told Nature. “Exercising is far easier if you ask me.”
The research was published in the March issue of Cell Metabolism.