Endurance athletes find success with paleo diets.

The results for Zabriskie were impressive, DeVore says. Over the course of their time together the 6-foot cyclist dropped his body weight from 168 pounds to 154 while improving his dead lift from 150 pounds to 245. This while increasing his power on the bike by about 15 percent.

"The assumption has always been that glucose was the preferred fuel with regard to performance," Sisson says. "I used to joke back in my days of sugar burning that, ideally, you would hang an IV bag off the back of your bike and just drip glucose into your bloodstream the whole way."

But Sisson has changed his mind. He says that one of the problems with the few studies conducted on low-carb performance to date is that they were done on athletes who had not yet fully adapted to burning fat as a primary source of fuel, a process that can take weeks, if not months. These flawed studies made paleo a tough sell. "This is a leap of faith that a lot of athletes are unwilling to take," he says. "Imagine you've been doing things a certain way for five or 10 years. And all of the sudden some guy comes along and says he thinks there's a better way. But there's no guarantee."

Dr. Stephen Phinney, a professor emeritus at UC Davis, has spent three decades studying low-carb performance. The mainstream consensus has been that you need carbs to do anything other than very moderate intensity exercise. But after a period of adaptation, the body will switch over from carbohydrate to fat as its main fuel for exercise with equal or better performance. That makes an athlete essentially "bonk-proof," says Phinney.



http://www.mensjournal.com/health-fitness/nutrition/paleos-latest-converts-20130618