By Ruth Kava, Ph.D., R.D.
Posted: Friday, July 12, 2002
ARTICLES
Publication Date: July 12, 2002
One of the freedoms we Americans hold dear is freedom of choice — we want to be free to choose where we live, our type of transportation, what we wear (or don't), who our leaders are, and what we eat and drink. And in most cases, we really do have a lot of choice. Nowhere is this more true than with respect to food. It would be nice, however, if we could make reasonable, informed choices about our diets. Since most of us aren't nutrition experts, we rely on those who are to help us make at least some of those choices, at least some of the time.
Lately, however, such reliance has been more difficult than usual.
First, there was the long article in the July 7 Sunday New York Times magazine questioning whether a low-fat diet is really good for us. Would it perhaps be better for heart, girth, and overall health to follow the much-maligned but slowly-gaining-acceptance Atkins high-fat, eat-all-the-butter-you-can, ketogenic diet?
Just a day later, Time magazine published a long article on the pros and cons of going vegetarian — if, of course, you can figure out exactly what a vegetarian is (there are several levels of severity).
And then, but one day after that, noted anthropologist Lionel Tiger chimed in with an opinion piece in the Wall Street Journal. He offered us historical (rather than hysterical) reasons to follow a diet based on meat and such — like the ones our cavemen forbears supposedly enjoyed (when they could catch it, that is).
So, here we are, being bounced back and forth like ping pong balls, with factions on all sides claiming that whatever evidence there is supports their views. The idea seems to be that if we only ate a preponderance of our calories from _______ (fill in your favorite macronutrient: fat, carbs, or protein) we would stem the tide of obesity that threatens to engulf us, diminish the incidence of heart disease, and perhaps promote world peace.
It's all well and good to picket for one's favorite food, but there does seem to be one item missing from most popular discussions of dietary advice, including the three mentioned above. That item is the importance of energy balance — that is, calories in (as food) versus calories out (as physical activity, including exercise). Maybe because it's hard to measure accurately in a population with widely divergent lifestyles, energy balance often seems to be left out of most popular discussions of nutrition and weight loss advice.
Yet, unless and until the laws of thermodynamics are repealed (for example, energy can neither be created nor destroyed) the most important determinant of an adult's body mass is his or her energy balance. But in spite of this relationship, we seem to get hung up over and over again on the form our calories take, rather than the sheer bulk of them.
While it certainly may be true that some populations who consume a relatively high proportion of their calories from fat (e.g., some folks in the Mediterranean region) have less heart disease than we do, it's also true that other populations with less heart disease eat less fat than we do. So it can't be just the fat, and it can't be just the diet, in my opinion.
We don't eat like cavemen, as Lionel Tiger urges, but we're not active like cavemen, either. The activity trends in this country seem to have been pointing down for the last several decades. And that's not just because of more TVs and computer games, though certainly these play a role. All sorts of subtle changes in society contribute to our diminishing exertion. Those of us over a certain age can even recall when driving a car took more physical energy than it does today. Remember trying to parallel park a car without power steering? Or having to actually move the seat manually without a power-assist?
Small differences add up but are hard to track. Before we bounce again between the high carb and high fat factions and waste a lot of time and energy arguing which is the best diet, let's stop and think a bit about our high energy in/low energy out lifestyles. It ain't a pretty picture, but it's a good predictor of what size we'll end up being. And eating like a caveman won't necessarily change that.
Ruth Kava, Ph.D., R.D. is ACSH's nutrition expert.
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| Responses:
July 15, 2002
Congratulations to Ruth Kava on her "caveman" article — an excellent balance.
— earle
September 9, 2002
Hi. Great article — I agree entirely. In my position as a health promoter of nutrition and physical activity for public health in New Zealand, I come across people who want to argue these points all the time and who tend to listen to the "doctors" who write these diet books rather than the common sense argument that Ruth writes about. Why do people continually forget about physical activity when they're looking at weight gain?
Keep up the good work.
Anne Kauika
September 9, 2002
Ruth Kava makes an important point when she notes that exercise (calories out) is important. It is important to look at all three questions: What are the best foods to eat? How many calories do I need? How much exercise do I need?
As beautifully discussed in the book Paleolithic Prescription, answers to these key questions can be found by examining the types and amounts of food and exercise our genes evolved with. These are the manufacturer's specifications for the human gene machine. When we buy a car, we want to know how much oil to put in it, what type of gasoline (diesel, high octane) it uses, and what road conditions it is built for (off road? maximum speed? etc.). If the car is built for diesel, we would not be surprised to learn that using premium gasoline eventually causes some serious problems.
So, what are the manufacturer's specifications for the human gene machine? Simply, they are the types and amounts of foods and the level of exercise under which the human genome evolved. For four million years hominids ate fruits, vegetables, and low-fat meat. This supplied low glycemic carbohydrates; abundant vitamins, minerals, and phytochemicals; a variety of fats made up of 50% monosaturates, 25% saturates, 18% omega 6, and 7% omega 3; and a variety of proteins that did not cross-react with self proteins. Humans also evolved with a high supply of daily sunshine (vitamin D, etc.) in a subtropical environment. Of course, aerobic and resistance exercises were common most days. This can be regarded as the optimal nutritional and exercise regimen for the human gene machine, and deviations from it have negative consequences (genetic failures). The severity of the genetic failures (disease) is related to an individual's genes and the amount of deviation. Smoking may have minor effects on one person (set of genes) after seventy years but may have devastating consequences on another person after a decade.
Conversely, the closer one approximates the "Paleolithic" regimen, the fewer and the smaller the genetic failures. With this in mind, one can readily see how the current "my diet is better than yours" argument has grown. The current Western nutritional regime has many major deviations from the optimal, gene-compatible, Paleolithic one. The main differences include: (1) a huge increase in high glycemic carbohydrates (sugar, grains), (2) a large reduction in low glycemic carbohydrates (fruits, vegetables), (3) a deficiency of many vitamins, minerals and phytochemicals due to a lower consumption of fruits and vegetables, (4) a huge increase in saturated fat due to consumption of grain fed animals, (5) a huge reduction in omega 3 EFA due to a decrease in consumption of wild game and fish, (6) a huge increase in novel, cross-reactive proteins due to completely new food types (grains, legumes, dairy), (7) a huge increase in salt consumption, (8) a huge decrease in vitamin D supply due to migration to high latitudes, clothes, and indoors jobs.
Each of these deviations is implicated in one or more chronic diseases. Any proposed diet that improves on the deviations of our Western diet is going to gain some followers because it will improve things. The vegetarian diet counters the problem of high saturated fat intake and increases vitamin, phytochemical, and mineral supply due to increased vegetable and fruit consumption. Thus, it is an improvement even though it still includes many problematic deviations. The Atkins low-carbohydrate diet counters the problem of a high consumption of high glycemic carbohydrates and is thus also an improvement over the current regimen. However, like the vegetarian approach, it also includes numerous major deviations from the optimal regime. Thus, when people argue about the relative merits of a vegetarian versus an Atkins, diet they are really arguing about the lesser of two evils because both contain various problematic foods, which result in chronic disease. Would you rather be shot or hung?
The Paleolithic diet is most compatible with our genetic make-up and will lead to the fewest and smallest genetic failures. It has all the benefits of a vegetarian diet as well as those of the Atkins diet but avoids the problematic foods included in these regimens. The closer one approximates such a diet, the healthier one will be. It is simply common sense to put the fuel/ food in your gas tank/gut that is most compatible with the internal machinery/genes.
I agree with Ruth Kava that we all can make our own food choices, but for those who want to lower the risk of chronic disease, a Paleolithic nutritional regime is the informed choice. The same Paleolithic advice goes for exercise level and amount of calories.
—AEmbry |
