I'm also of the understanding that running totally on fat for fuel is not a good strategy for longevity, but that a low carb ( 50g/day) or very low carb (less than 30g/day) diet that is high in fat but keeps the muscles and possibly the brain running on mostly glucose is more conducive to a longer life span.
Lex
I think Lex might be on the right track about this.
First of all, I would like members to know that I don't think dietary carbs are necessary by all means. There are many, including Lex and Inuits living few hours above me (yes, I'm in Canada
) who are in marvelous health without it. Every one on this forum knows that low carb, high fat, and preferably raw eating plan is lot superior. However, because there is no longterm study that compares levels of carbs, proteins, and fat that is optimal, we should be open minded about possibility of moderate amount of carbs of maybe 20-50g a day could be beneficial than no carbs at all despite the obvious harms they could do as well. As Lex mentioned in later post, life is all about trade-offs. Maybe carbs are so evil that we should do everything in our reach to eliminate them or maybe little bit of fructose is needed to metabolize dietary fats better. Those so called anti-oxidants are maybe indeed helpful that it may be worth eating few veggies and fruits or maybe the anti-nutrients in them do more harms than good. The point here is that because we're not the one who created the world, we would never know the absolute truth of one perfect diet that fits all.
I have an abusive history with carbs; I fear them and wanted to eliminate them from my life entirely. Unfortunately, I'm not as strong willed as Lex or Crag, so I tend to stay very low carb for few days then binge on carbs (..oh dear, I didn't want to admit this) when my muscles start to give out, I can't concentrate nor think clearly, and my sugar craving get so intense that I feel suicidal. So I have been doing CKD unintentionally, I suppose. I wish I could be more strict with myself that I would actually adapt my system to run on fatty acids and ketones, however, knowing that having a glucose-based metabolism may not be the end of the world makes me somewhat less miserable.
Interesting point is that Dr.K of optimal diet, who advocate very high fat eating plan, suggests enough carbs of 30-60g a day that will be used by brain, and good quality animal protein in moderate amount coupled with lots of animal fat. He insists that too much protein strains the body and that his plans focus on optimal health and well-being of the individuals rather than just weight loss or muscle growth. He has apparently cured many diseases including cancer and many reported tremendous improvement in terms of their health. Is his plan superior to any other WOE including high-protein, VLC, or zero-carb? We don't know. But I'm trying to stay open-minded about possibility of moderate amount of carbs from good sources may be beneficial and Lex's comment about possibility of the brain running on mostly glucose is more conducive to a longer life span could be true as well.