Decreasing the muscle's insulin requirements through exercise cuts down on insulin resistance to a large extent. This means that insulin can bind more easily to the cell receptors and be more effective in promoting glucose uptake. Now, despite what Sears and others claim, most Americans are not insulin resistant. So insulin problems should not be a factor for the majority of us. Therein lies the myth source.
Many powerful forces make it so.
The cagey purveyors of snake oils and gimmick diets know this. They're master at their craft of deception. Dietary carbohydrate as an ergogenic aid for prolonged and brief competitions in sport. J. Sports Nutr. Carbohydrate intake is likely to be the most important for high power activities when the athlete has been losing weight due to a negative energy balance.