(NaturalNews) Weight training may trigger metabolic changes in the body that help maintain a healthy weight and reduce the risk of Type 2 diabetes, according to a study conducted by researchers from the Boston University School of Medicine and published in the journal
Cell Metabolism.
Scientists have long believed that only aerobic exercise that builds up long-term endurance, such as running, has any notable effect on the body's metabolism. This kind of exercise produces what is known as "type I" muscle, which is designed for a long, slow output of energy. In contrast, "type II" muscle, which is used for sprinting or lifting heavy weights, is more powerful, but only in the short term.
Researchers genetically engineered mice so that their bodies would produce more type II muscle when a specific gene was switched on. With the gene switched off, the mice were fed a high-calorie, sugary
diet for eight weeks. As expected, the mice became obese, developed
fatty liver deposits and became
insulin resistant, just like humans on a similar diet.
When the researchers switched the gene on and the mice began to bulk up with type II muscle, the
animals quickly lost weight and were cured of their insulin resistance and fatty
liver disease. Significantly, the mice did not increase their level of
exercise and continued with the high-calorie diet.
"We've shown that type II muscle does more than allow you to pick up heavy objects," said researcher Kenneth Walsh. "It is also important in controlling whole-body
metabolism."
While the animals did not remain
fat as researchers expected, they also did not become skinny like marathon runners; instead, they became lean like sprinters. Significantly, the mice's long-term endurance on a treadmill test was not improved after the gene was switched on.
"These data ... suggest that
strength training, in addition to the widely prescribed therapy of endurance
training, may be of particular benefit to overweight individuals," the researchers wrote.
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