Your body does not work harder just because the food has high glycemic index, I would say it is the opposite. The body has a very easy time using glucose for example compared to fructose which needs to through the liver which in turn increases the risk of liver damage if you eat too much.

However I was obviously referring to the weight gain and loss I mentioned in my previous sentence. I.e. the long distance runners in your link that chooses high glycemic food are not getting fat anytime soon.