A quick note about ketosis:
Fat-adaption does not necessarily mean ketosis. Ketosis is ketosis. Fat-adaption describes the ability to burn both fat directly via beta-oxidation and glucose via glycolysis, while ketosis describes the use of fat-derived ketone bodies by tissues (like parts of the brain) that normally use glucose. A ketogenic diet “tells” your body that no or very little glucose is available in the environment. The result? “Impaired” glucose tolerance and “physiological” insulin resistance, which sound like negatives but are actually necessary to spare what little glucose exists for use in the brain. On the other hand, a well-constructed, lower-carb (but not full-blown ketogenic) Primal way of eating that leads to weight loss generally improves insulin sensitivity.