It's a component of the Standard American Diet (SAD), and most experts say that it's bad for our bodies. But now researchers have discovered that one very specific type of fat actually can increase our metabolisms, reported Medical News on October 3.
Conducted by Texas Tech University nutrition scientists, the study shines a light on different ways that supplements and diet can boost metabolism, said lead researcher Chad Paton, an assistant professor of nutritional biochemistry.
The study began with a vow to determine why skeletal muscles of obese people contained a certain type of enzyme that breaks down saturated fats. The enzyme, called SCD1, transforms saturated fat into monounsaturated fat, which is easier to metabolize.
Professor Paton explained that skeletal muscles only produce SCD1 in heavily exercised muscle tissue. However, it's also produced in the case of obesity. When he and his team compared skeletal muscles of the genetically modified mice to those of the wild mice, they uncovered higher levels of polyunsaturated fats, especially linoleic acid.
But because those higher levels of linoleic acid could be attained only through diet, the modified mice had to be eating more food, even though they weighed less. In addition, Professor Paton discovered that the modified mice boosted their ability to exercise.
"We found in the genetically modified animals that they had a hypermetabolic rate," he said. "They were increasing their energy consumption, and they experienced greatly increased exercise capacity. For example, on the exercise wheels, normal mice fatigue after 7 to 10 minutes. These genetically modified animals wouldn't fatigue for about 70 minutes. So they were running a lot longer. Sedentary mice looked more like exercise-trained mice. That really made us look in a lot more detail what was happening in the skeletal muscle."
The key to their discoveries: Linoleic acid turned on on part of the muscle cell's DNA that encouraged the cells to make more mitochondria. It also switched on a protein that encouraged the cell to burn off excess energy from the extra food as heat - a process called uncoupling.
While storing unused energy as fat worked for cavemen, it's not so great in our sedentary culture.
"That's where we have taken our research from this," he said. "You can't change the human genome, but that gives us insight if you could activate the same part of the DNA in human in skeletal muscles that burn off excess energy as heat instead of storing it. Perhaps it's a supplement people could take that will turn on the cells' metabolic machinery burn off energy and increase mitochondria."