Riiighhhhtt.....I guess that's why study after study has shown that those who lose weight via low carb consistently lose less lean body mass (that's muscle) than those who lose weight via high carb/low fat, usually by a good amount less.
What I'd love to see this guy explain is why on earth your body would convert muscle to fat when it's already got an abundent supply (of fat, that is) and you have ample protein coming in to support that muscle.
I will buy that if you go off the plan and go back to your old eating habits that the majority of the weight you gain back will be fat and not muscle, but I think they're missing the point of low carb in that you're not supposed to ever go off the plan...you move to maintainence once you reach your weight loss goals.