I just got through Jeff Volek and Stephen Finney's Art and Science of Low Carbohydrate Performance. It's worth the $6 Kindle price if you happen to have an e-reader: http://www.amazon.com/The-Art-Science-Carbohydrate-Performance/dp/0983490716
One of the things that struck me is the authors' claim that they and other athletes have maintained uninterrupted ketosis for months and even years at a time.
It seems that a lot of athletes in the paleo community (myself included) find the need for carb refeeds. I'm sure I dip into ketosis every once in a while, but the amount of veggies I consume on a regular basis (around 100g carbs) is unlikely to have me in full ketosis. I've found bi-weekly refeeds work best. When I need a refeed, I can feel it, and they do wonders for bringing recovery and energy back up to full levels.
But what of these athletes claims in the book (ultra marathoners even) that they can maintain uninterrupted ketosis for months at a time? Is there a point at which a ketogenic diet (less than 50g/day of carbs) mitigates the need for a carb refeed on a more standard paleo diet that is not as carb strict (between 50-150g/day)? What would the mechanisms be? Or is this just standard variation between individual needs?