What if the Paleolithic diet not the best diet for longevity?
s a doctor that has been promoting a high-fat, low carb, and restricted protein diet for almost two decades, I have long been saying that one cannot use paleolithic nutrition as a basis to determine optimal diet. Although a paleolithic diet may not be a bad diet and often is good (depending on which paleolithic diet one is talking about), the entire premise of using paleolithic nutrition as a basis to obtain an optimal diet is flawed.
Nature is concerned about reproductive success, not about significant post-reproductive health and lifespan. In other words, nature really doesn't give a hoot how long we live, unless it pertains to reproductive success. Therefore, we cannot look to nature or count on nature or what's "natural" to tell us how to live a long healthy (post-reproductive) life. To obtain an optimal diet (as opposed to just a better diet that would be virtually any diet that deviates from the standard American diet) one must use modern science that one could even consider to be "unnatural".
(See below - short excerpt from my book)
The science of insulin and leptin clearly reveal that a diet high in non-fiber carbohydrates is extremely unhealthy and shortens lifespan. Furthermore, considerable and robust science tells us that excess protein (any protein beyond that necessary to build, repair, and maintain oneself) is equally detrimental (see links below to a couple of PowerPoints of talks I have given). Oil and fat is really the only relatively safe fuel to burn, and ones diet should consist mostly of this along with the necessary protein and minimal non-fiber carbohydrates, whether or not this sort of diet was paleolithic.
From p.46, "The Rosedale Diet" - LONGEVITY ISN'T NATURAL
Within the billions of years that life has evolved on earth, we may have become smarter, more complicated creatures than our single-celled predecessors, but the fact is, we are here for pretty much the same reason. As Mother Nature sees it, whether you are a single-celled organism, a multi-celled nematode, a bird, a dog, a cat, or a human, you are here for the primary purpose to reproduce and pass your precious genes (the library of life) on to the next generation. After that, you're expendable. My patients are shocked when I tell them that there is nothing "natural" about trying to live as long a life as possible. You may want to hang around to be a healthy 120 and spend your last decades playing with your great-grandchildren, writing your novel, or traveling the world, but Mother Nature has other ideas. Mother Nature's primary concern is to keep you alive long enough to reproduce, and maybe a bit longer after that to care for your young. That's it.
Some scientists believe that our cavemen ancestors followed an ideal diet for our health and longevity because they ate the "pure" and "natural" diet that we all evolved from. In reality, the so-called "paleolithic diet" followed by cavemen was not necessarily ideal for long-term health; in fact, it was sort of random. Cavemen ate whatever Mother Nature made available to them at the time. Keep in mind, Mother Nature didn't give a hoot about eating for a long, healthy life; she just wanted cavemen to make more baby cavemen. You see why I say there's nothing "natural" about the quest for longevity? If anything, in order to achieve longevity, you have to circumvent Mother Nature and consider some "unnatural" alternatives. By that I mean you have to "trick" Mother Nature at her own game.
Nature has very ingenious ways to help a species survive. When food is scarce, as it often was for our more primitive ancestors, in order to ensure the survival of a species, nature developed a method of keeping an organism alive through times of famine so that it could reproduce at a later, more opportune time. Reduced food intake turns on genes that protect the body against aging, allowing it to hopefully outlive the famine. Instead of spending lots of scarce energy to make babies that couldn't survive, the body focuses its energy on maintaining and repairing itself. As soon as there is enough food available to support effective reproduction, the body switches gears and reduces its emphasis on maintenance and repair and directs its energy toward reproduction.
When you are in maintenance and repair mode, the body's "body shop" is revved up and ready to go. Calorie-restricted animals have measurably higher levels of key chemicals that allow for extended life, protect cells from damage, and promote repair.
You don't have to starve yourself to turn on the maintenance and repair switch. Following the Rosedale Diet will do the same good things for your body. How does it work? Leptin is a key player (perhaps in concert with insulin) in the evolutionary tug of war between whether the body should concentrate on reproduction or maintenance and repair.
...and to live a long, healthy, post-reproductive lifespan, we want our bodies to concentrate on maintenance and repair. To do that we must use modern science that tells us that we must regulate the hormonal nutrient sensors that, when kept low, turn up the genetic expression of maintenance and repair.