Fat can be good sometimes, a new study conducted by Texas Tech University nutrition scientists found that a diet containing certain type of fat might help humans to lose weight as it increases metabolism.

Scientists say that the skeletal muscles of obese people contain a certain type of enzyme that breaks down saturated fats. The enzyme, SCD1, converts saturated fat into monounsaturated fat, which is easier to metabolize. The liver produces this enzyme depending on the fat content present in the food consumed.

In order to determine the function of the enzyme, Chad Paton, an assistant professor of nutritional biochemistry in the Department of Nutrition, Hospitality and Retailing and colleagues from the University of Wisconsin - Madison, genetically modified mice so that their muscles would constantly produce this enzyme. The researchers found that the mice that produced this enzyme exhibited a faster metabolism.

"We used a transgenic mouse model, and we took the gene that makes the enzyme that's not normally expressed and took away it's regulation to make it active all the time," Paton said in an official statement. "What we found in those animals is they had a hypermetabolic rate compared to the wild mice, increased energy consumption and greatly increased these animals' exercise capacity."

After comparing the skeletal muscles of the genetically modified with wild mice, Paton and his team found higher levels of polyunsaturated fats, particularly linoleic acid. This particular acid can be received only through diet. The presence of the acid caused the modified mice to eat more food and increased their ability to exercise. As a result, they weighed less than the wild mice.

"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 researchers said that a good appetite and more SCD1 enzyme results in more linoleic acid in the tissues.

"The linoleic acid switched on part of the muscle cell's DNA that encouraged the cells to make more mitochondria and to turn on a protein that encouraged the cell to burn off excess energy from the extra food as heat," the researchers said.

Paton said that humans store unused energy as fat. In the past, the fat helped ancestors survive, but it now leads to obesity and other health problems. While it is impossible to genetically modify humans, he said that this experiment could be useful in adapting diets to achieve the same results in humans.

"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."

The findings are published in the Journal of Lipid Research.

Tags Fat, Humans, Weight, Texas, Texas Tech University, Nutrition, Diet, Metabolism, Obese