Our muscles burn sugar. When the sugar stored in the muscles is consumed, the body turns to stored energy. Many of us on low carb plans are overweight and thus have plenty of stored energy to burn without our bodies converting our muscles into fuel. So what this guy is saying might be true for athletes but really does not apply to the average person out there. As long as one is putting high quality fuel into there bodies (i.e. limiting processed foods) then you should be okay an feel great on a low carb regime.