- Cordain, Loren.
The Paleo Diet.
Hoboken, NJ: John Wiley & Sons, 2002.
ISBN 978-0-470-91302-4.
-
As the author of a
diet book,
I don't read many self-described “diet books”. First
of all, I'm satisfied with the approach to weight management
described in my own book; second, I don't need to lose weight; and third,
I find most “diet books” built around gimmicks
with little justification in biology and prone to prescribe
regimes that few people are likely to stick with long enough to
achieve their goal. What motivated me to read this book was
a talk by
Michael Rose
at the
First Personalized
Life Extension Conference in which he mentioned the concept
and this book not in conjunction with weight reduction but rather
the extension of healthy lifespan in humans. Rose's argument, which
is grounded in evolutionary biology and paleoanthropology, is somewhat
subtle and well summarised in
this
article.
At the core of Rose's argument and that of the present book is the
observation that while the human genome is barely different from that
of human hunter-gatherers a million years ago, our present-day population
has had at most 200 to 500 generations to adapt to the very different diet
which emerged with the introduction of agriculture and animal husbandry.
From an evolutionary standpoint, this is a relatively short time for
adaptation and, here is the key thing (argued by Rose, but
not in this book), even if modern humans had evolved
adaptations to the agricultural diet (as in some cases they clearly
have,
lactose tolerance
persisting into adulthood being one obvious example), those adaptations
will not, from the simple mechanism of evolution, select out diseases
caused by the new diet which only manifest themselves after the age of
last reproduction in the population. So, if eating the agricultural diet
(not to mention the horrors we've invented in the last century) were
the cause of late-onset diseases such as cancer, cardiovascular problems,
and type 2 diabetes, then evolution would have done nothing to select out
the genes responsible for them, since these diseases strike most people
after the age at which they've already passed on their genes to their
children. Consequently, while it may be fine for young people to eat
grain, dairy products, and other agricultural era innovations, folks over
the age of forty may be asking for trouble by consuming foods which evolution
hasn't had the chance to mold their genomes to tolerate. People whose ancestors
shifted to the agricultural lifestyle much more recently, including
many of African and aboriginal descent, have little or no adaptation to
the agricultural diet, and may experience problems even earlier in life.
In this book, the author doesn't make these fine distinctions
but rather argues that everybody can benefit from a diet
resembling that which the vast majority of our ancestors—hunter-gatherers
predating the advent of sedentary agriculture—ate, and to which
evolution has molded our genome over that long expanse of time. This
is not a “diet book” in the sense of a rigid plan for
losing weight. Instead, it is a manual for adopting a lifestyle,
based entirely upon non-exotic foods readily available at the
supermarket, which approximates the mix of nutrients consumed by our
distant ancestors. There are the usual meal plans and recipes, but the
bulk of the book is a thorough survey, with extensive citations to the
scientific literature, of what hunter-gatherers actually ate, the
links scientists have found between the composition of the modern
diet and the emergence of “diseases of civilisation” among
populations that have transitioned to it in historical times, and the
evidence for specific deleterious effects of major components of the
modern diet such as grains and dairy products.
Not to over-simplify, but you can go a long way toward the
ancestral diet simply by going to the store with an “anti-shopping list”
of things not to buy, principally:
- Grain, or anything derived from grains (bread, pasta, rice, corn)
- Dairy products (milk, cheese, butter)
- Fatty meats (bacon, marbled beef)
- Starchy tuber crops (potatoes, sweet potatoes)
- Salt or processed foods with added salt
- Refined sugar or processed foods with added sugar
- Oils with a high omega 6 to omega 3 ratio (safflower, peanut)
And basically, that's it! Apart from the list above
you can buy whatever you want, eat it whenever you like in
whatever quantity you wish, and the author asserts that if
you're overweight you'll soon see your weight dropping toward
your optimal weight, a variety of digestive and other problems
will begin to clear up, you'll have more energy and a more consistent
energy level throughout the day, and that you'll sleep better.
Oh, and your chances of contracting cancer, diabetes, or cardiovascular
disease will be dramatically reduced.
In practise, this means eating a lot of lean meat, seafood,
fresh fruit and fresh vegetables, and nuts. As the author points out,
even if you have a mound of cooked boneless chicken breasts, broccoli,
and apples on the table before you, you're far less likely to pig out
on them compared to, say, a pile of doughnuts, because the natural
foods don't give you the immediate blood sugar hit the
highly glycemic
processed food does. And even if you do overindulge, the caloric
density in the natural foods is so much lower your jaw will get tired
chewing or your gut will bust before you can go way over your calorie
requirements.
Now, if even if the science is sound (there are hundreds of
citations of peer reviewed publications in the bibliography, but
then nutritionists are forever publishing contradictory
“studies” on any topic you can imagine, and in any
case epidemiology cannot establish causation) and the benefits from
adopting this diet are as immediate, dramatic, and important for
long-term health, a lot of people are going to have trouble with
what is recommended here. Food is a lot more to humans and other
species (as anybody who's had a “picky eater” cat can
testify) than just molecular fuel and construction material for
our bodies. Our meals nourish the soul as well as the body, and
among humans shared meals are a fundamental part of our social
interaction which evolution has doubtless had time to write into
our genes. If you go back and look at that list of things not
to eat, you'll probably discover that just about any “comfort
food” you cherish probably runs afoul of one or more of
the forbidden ingredients. This means that contemplating the adoption
of this diet as a permanent lifestyle change can look pretty grim,
unless or until you find suitable replacements that thread among the
constraints. The recipes presented here are interesting, but still
come across to me (not having tried them) as pretty Spartan. And
recall that even Spartans lived a pretty sybaritic
lifestyle compared to your average hunter-gatherer band.
But, hey,
peach fuzz
is entirely cool!
The view of the mechanics of weight loss and gain and the
interaction between exercise and weight reduction presented
here is essentially 100% compatible with my own in
The Hacker's Diet.
This was intriguing enough that I decided to give it a try
starting a couple of weeks ago. (I have been adhering, more or less,
to the food selection guidelines, but not the detailed meal plans.)
The results so far are intriguing but, at this early date, inconclusive.
The most dramatic effect was an almost immediate (within the first three
days) crash in my always-pesky high blood pressure. This may be due entirely
to putting away the salt shaker (an implement of which I have been
inordinately fond since childhood), but whatever the cause, it's taken
about 20 points off the systolic and 10 off the diastolic, throughout
the day. Second, I've seen a consistent downward bias in my weight.
Now, as I said, I didn't try this diet to lose weight (although I could
drop a few kilos and still be within the target band for my height and
build, and wouldn't mind doing so). In any case, these are short-term
results and may include transient adaptation effects. I haven't been
hungry for a moment nor have I experienced any specific cravings (except
the second-order kind for popcorn with a movie). It remains to be seen
what will happen when I next attend a Swiss party and have to explain that
I don't eat cheese.
This is a very interesting nutritional thesis, backed by a wealth of
impressive research of which I was previously unaware. It flies in the
face of much of the conventional wisdom on diet and nutrition, and yet
viewed from the standpoint of evolution, it makes a lot of sense. You will
find the case persuasively put here and perhaps be tempted to give it a try.
December 2010 