Swimming 6 hours a day is simply not an option for everybody. Besides, even with enough exercise I would imagine that some diets would still make you sick, for example if all you ate were chocolate and ice cream. (Note that I don't advocate the low-carb diet from the article).

The "not selling anything but..." bothered me too, also "Thirdly, he is very smart. His reasoning is immaculate and he knows a lot more than your average doctor or nutritionist." The doctors on TV trying to sell me on chocolate bars also look very smart...