Another possibility -- and this is really speculation, because as I've said I'm not a doctor -- is that the diet actually works best when it is a high calorie diet with a lot of fat. The idea is that we consciously or subconsciously try to restrict calories on the diet and so our body still thinks it's in starvation mode, even with the absence of carbohydrates, and holds on to the fat. I have no idea if this is the case -- it's the kind of thing that, in an ideal world, would be studied by obesity researchers.

Editor's note: If you're having trouble with your diet, talk to your doctor, dietician or CDE.

3. Dr. Richard K. Bernstein is the diabetes guru of low carb. I notice that you don't mention him in your book. What do you think of his recommendation that we limit our carb grams to 6 grams of slow-acting carbohydrates at breakfast, 12 grams at lunch and at dinner, plus 12 grams for a snack (Dr. Bernstein's Diabetes Solution,2007, p. 169 and 172)?

I did not mention Dr. Bernstein in my book, but only because I was concentrating on making the argument that we should have known all along -- say for 40 years, at least -- that refined, easily-digestible carbohydrates and sugars are the cause of weight gain and the associated chronic diseases. When it comes to the best way to keep diabetes under control, however, I defer to Dr. Bernstein's clinical experience and his wisdom in these matters. You can't do better than reading Dr. Bernstein's books and following his advice.

5. EFAs and optimizing insulin sensitivity Did you find any research about essential fatty acids affecting insulin sensitivity?

I did, but nothing convincing. The only thing I could suggest with reasonable certainty is that carbohydrates are the problem. Everything after that strikes me as guesswork.

6. My wife tells me that Overeaters Anonymous used to advocate getting rid of carbs (she still has the old recipe book) but now has allowed a variety of diets, including those that conform to the low-fat guidelines promoted by the government. Is there a story behind this shift?

Also, everything you say about non-Western diets fits with the Paleolithic diet. Any comments on that diet?

I didn't see the early advice from Overeaters Anonymous, but I do know that Weight Watchers used to advocate getting rid of the carbohydrates until the government shifted the playing field and the low-fat diets came into vogue. As for the Paleolithic diet, I agree with most of its principles. Fundamentally, it begins by getting rid of the carbohydrates. My only question is whether or not there is some "ideal" balance of nutrients and micronutrients that will maximize our health and longevity. The Paleolithic diet implies there is. As I have already said, I feel that the best we can say is to stay away from the kinds of carbohydrates we know for sure we didn't evolve to eat. After that, the Paleolithic diet depends on educated guesses. They may be very good guesses, but there's no way to tell for sure.