Sunday, October 26, 2014

We should ask John Lehr about this

kw: book reviews, nonfiction, dieting, self help, paleo diet theory

I've read and heard snippets about a "Paleo Diet", so I figured it is time to look into it. I read Your Personal Paleo Code: The 3-Step Plan to Lose Weight, Reverse Disease, and Stay Fit and Healthy for Life, by Chris Kresser. The thesis of this diet and self help movement is that we evolved for a million years or so eating a certain way, but in the past 10,000 years or so the agricultural revolution and then the industrial revolution have changed the kinds of foods we eat, and we aren't well fitted to the "modern diet".

Perhaps you've heard of the "no white stuff" diet: no bread or dairy, but eat lots of meats, fowl and fish, and all the fruits and greens you can stand. It seems to be a spinoff of the low/no-carbohydrate Atkins Diet. That is largely where the first section of the book is going.

The author tells us that hunter-gatherer peoples are healthier than we are, and that our ancestors were healthier still. We read that the grain-based diet in all agricultural societies is to blame for chronic illnesses such as heart disease and diabetes. Thus we need to eat more like our pre-agriculture ancestors.

It isn't really that simple, because, he explains, there was no single all-encompassing diet in the paleolithic era, which ended about 12,000 years ago. Those dwelling inland would eat quite different foods than seacoast peoples—who ate much more fish and shellfish—and the Arctic diet was about 90% blubber, as it still is.

He does point out that life expectancy at birth was about 22 years in 10,000 BC, but goes on to say that it fell to about 19 years a few thousand years later, based on archaeological studies primarily in the "Fertile Crescent", or Mesopotamia. I personally attribute that to a great increase in violence as people lived in groups larger than the typical gatherer group of 50-150 souls.

This is a bigger evolutionary adjustment: For millions of years, few members of any species in the genus Homo encountered non-relatives on any frequent basis. If they did, a fight to the death was the ordinary result. This is still true in parts of Papua New Guinea and Amazonia. Once agriculture came along, people began to live in larger and larger groups, and reflexes that were appropriate on the savannas became a problem. We are still learning to get along with strangers, and we're probably evolving more "civil" attributes. In most of the "civilized world", people are able to go about their daily activities without attempting to kill every stranger they see, because that would mean attacking nearly everyone encountered! This is attested by the steadily declining murder rate, documented pretty well for at least 1,000 years. I have written before that in Shakespearean England the murder rate was at least 10 times what it is in modern cities, and 100 times the rate in more rural areas.

Mr. Kresser does write that certain evolutionary changes have occurred as a result of agriculture; things such as tolerance for lactose and gluten. I don't know how many Cro-Magnons would have suffered celiac symptoms from eating wheat (or proto-wheat), but among modern populations of European origin, the rate of gluten intolerance is about 0.75% (1 in 133). Even among Asians, who are famously lactose intolerant, about one in three can drink milk, my wife included.

We really don't know whether any elderly Cro-Magnons had heart attacks, strokes, or cancer. I suspect "old" was closer to 40 than to 70, so they didn't usually live long enough to get "chronic" conditions. As I have also written in earlier posts, human evolution continues at a good clip. Wisdom teeth are on their way out, and another century or two could see a precipitous drop in rates of celiac disease and lactose intolerance, and possibly diabetes as well.

Anyway, for those who'd like to eat Paleo, this book is probably the best resource. The author is quite an enthusiast, but I would not call him a nutcase or fanatic. He is reasonable and persuasive. The second part of the book is advice about learning the kinds of foods you tolerate well, and the third is about building a life around your new/old (very old!) diet. He takes better account of human nature than authors of self-help books typically do, so his advice will be better followed by comparison. He also strongly stresses the need for more motion by all of us who are not professional athletes. I think all that walking has more to do with hunter-gatherer health than more or less meat or starch in their diet.

If I wanted to try the Part 1 diet, I'd find it hard to give up the starches I love: whole wheat bread and pasta, for example (My wife and I can both cook up a mean pot of spaghetti sauce or Stroganoff, though we tend to use ground turkey instead of beef). But I'd probably enjoy adding more steak or roast into my diet, compared to our present diet of chicken and fish, with only occasional beef or pork. Oh, and cheese! A Sunday evening favorite just before, or during, a "couch potato session" beginning with America's Funniest Videos, is a couple slices of bread topped with 6mm of cheese and microwaved; and I put cheese in any meat sandwich. A little tinkering around with his advice about macronutrient balance shows that my best calorie balance is 50% carbohydrate, 20% protein, and 30% fat. That's close to the way I eat now (whew!).

I began reading in a skeptical frame of mind, and came away with quite an appreciation for the author's insights into diet and activity (it's a better-received word than "exercise"). It is particularly appropriate that we learn to eat things that make us feel better hours or a day or two later, in preference to what might taste the best at the moment.

P.S. John Lehr? My favorite among the Geico caveman actors.

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