Scientists have found that physical exercise doesn’t just burn fat it also stimulates a gene that make our fat burning machinery work better. As this ScienCentral News video reports, that may give people even more incentive to hit the gym after the holidays. A Genetic Boost?Feasting on little, pink pellets may not sound as good as tucking into your turkey and stuffing, but to a lab rat the pellets may be as irresistible as fast food is to many of us. And, containing high amounts of fat, they’re just as unhealthy too.As part of her study of our metabolism — working to understand how energy goes astray in metabolic diseases such as obesity and diabetes — Duke University biochemist Deborah Muoio used the high-fat-pellet rat diet to study how muscles get energy from food. Muoio and her research team found that a high-fat diet interferes with the muscles’ ability to burn fat, a process that takes place in a part of a cell called the mitochondria — the powerhouses or engines of the cells. But exercise rescued the animals from the ill effects of their diet."When the animals were fed a high-fat diet and we studied their mitochondria, those mitochondria were not working efficiently,” she says, and when mitochondria aren’t burning fat properly the muscles can’t function as well. “There are many roadways in the mitochondria that ultimately allow them to burn fat. What we observed was somewhat of a traffic jam."In the skeletal muscle, the mitochondria take fuel, in this case carbohydrates and fats from the food we eat. The food is then converted by the mitochondria into another kind of fuel that allows muscle movement. After 12 weeks on the high-fat diet the animals developed early signs of metabolic syndrome: they gained weight, levels of blood fats were high and blood sugar levels also rose. “When the mitochondria are fed fat, they attempt to adapt so that they can utilize fats effectively,” Muoio says. “The problem is, if you think of it as a merging highway, certain parts of the highway adapt so there’s quite accelerated fat burning. But the other parts are not adapting, and so what occurs is somewhat of a bottleneck. As a result, fats are what we call ‘incompletely burned.’” She thinks that the presence of these incompletely burned intermediates may be what triggers insulin-resistance in the rats, an early sign of diabetes. “Obesity and diabetes go hand in hand… under conditions of a high fat supply to the muscle, the tissue becomes insulin-resistant, not responding to insulin properly,” Muoio explains. “If insulin isn’t working properly then blood sugar can rise to what is considered dangerously hi levels, and this causes damage in a lot of different tissues."But, as the researchers reported in the Journal of Biological Chemistry, when half of the rats were exercised for two weeks, while continuing to eat the diet, their blood sugar levels returned to normal, insulin sensitivity went back to normal, and at the same time there was an improvement in mitochondrial function.The exercise was found to have activated a gene called PGC1-alpha. The gene, which regulates how the mitochondria of muscle cells metabolize fuel — how well muscles burn energy. When the gene is activated it tells muscle cells to burn fat more efficiently, so the rat’s muscles stayed healthy, even as they continued their fatty diet.
