There's a tiredness and "brain fade" associated with these sort of diets. I'm not so sure it's the carb cutting so much as it is the extreme calorie restriction

There's a tiredness and "brain fade" associated with these sort of diets. I'm not so sure it's the carb cutting so much as it is the extreme calorie restriction. I used a protein sparing modified fast (which Atkins is a form of) that advocated supplementing sodium and potassium along with essential fatty acids using fish oil (it was a low fat and low carb diet). I've tried Atkins before and experienced the tiredness/brain fade. The PSMF I was on though caused me none of these symptoms. In fact, I felt precisely the opposite. During the diet, I experienced a form of mild euphoria.