The reason he’s doing this is that he discovered eating low-carb doesn’t necessarily mean being in ketosis, or at least not in the zone that Drs. Jeff Volek and Stephen Phinney call nutritional ketosis: a blood ketone level of between 0.5 and 3.0 mM. As they explain in their terrific book The Art and Science of Low-Carb Living, it’s within this zone that we can easily tap body fat for fuel and keep our brains happily supplied with ketones.
This is a pretty informative post from Tom Naughton about some of the differences between low carb and ketosis. Interestingly, I was just having a debate with a friend of mine the day before I came across this article. 🙂