Weight Training May Help Prevent Diabetes

A dumbbellResistance training may be more effective at preventing obesity and diabetes than previously thought according to a recent study conducted at the Boston University School of Medicine (BUSM).

Researchers engineered mice that could be made to grow type-2 muscle on demand by switching on a gene called Atk1 that regulates type-2 muscle development. In humans type-2 muscle is developed predominately through weight training and explosive exercise such as sprinting and is known as “fast twitch” muscle. Type-1 muscle is developed through endurance training such as long distance walking or running and is known as “slow twitch” muscle.

The mice in the study were fed a diet high in calories, fat, and sugar, similar to the composition of an unhealthy human diet. The mice initially grew obese, developed fatty livers and became insulin resistant – a sign of diabetes.

When the Atk1 gene was activated, the mice began developing type-2 muscle, similar to what a human would experience through weight training. The increase in muscle mass led to anĀ  improvement in insulin sensitivity, a reduction in weight and overall fat levels, and a reversal of the fatty liver disease in the mice.

The findings surprised the researchers who expected the mice to become strong but fat “sumo mice”. It had been well known that exercise in the form of running, jogging, and other endurance exercises can help reduce obesity and insulin resistance. Weight training however was not thought to be as effective at reducing weight and increasing an individuals insulin sensitivity.

The researchers believe that the loss in weight was due to an increase in the levels of fat oxidization in the body. Fat oxidization is the process by which fat in the body is converted into usable energy. When fat oxidization is impaired, the body cannot convert dietary fat into usable energy so an individual consumes more food to cover the energy deficit. the unoxidized fat is then converted into adipose tissue which leads to weight gain and an increase in body fat levels.

The authors write “Our findings indicate that an increase in fast/glycolytic muscle mass can result in the regression of obesity and metabolic improvement through its ability to alter fatty acid oxidation in remote tissues.”

Kenneth Walsh, who is the Professor of Medicine at BUSM and one on the researchers involved in the study added “We’ve shown that Type II muscle does more than allow you to pick up heavy objects, it’s also important in controlling whole-body metabolism.”

The study called “Fast/Glycolytic Muscle Fiber Growth Reduces Fat Mass and Improves Metabolic Parameters in Obese Mice” appears in the February 2008 edition of the journal Cell Metabolism.