Nutritional Anthropology

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The science and art of living the way nature intended

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NATURAL EATING
Nutritional Anthropology: 
Eating in harmony with our genetic programming

GEOFF BOND

 

CHAPTER ELEVEN
EXERCISE

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Looking at our genetic programming is a powerful technique for identifying the optimum way to feed ourselves. This same technique can be applied to other aspects of our lifestyles too. One of these is exercise. What is our genetic programming for exercise?

 

The Genetic Foundations

·      Over the millions of years of evolution, what were the patterns of physical activity practised by our species?

·      What will that tell us about the amount of exercise we should be getting today?

 

Surprisingly we can work out a lot about the physical activity of our Pleistocene ancestors. First of all we know how they must have foraged for food, how far they travelled, how fast, and even their muscular development.

 

Further, by studying contemporary forager tribes, we can see how they organised themselves on a daily basis.

 

A typical Pleistocene group consisted of thirty-five to forty five people, roughly equally divided between men and women. This group would camp in one place for a few days and then move on make another camp 10 to 20 miles away. They carried very little with them, but they still had to walk all the way! They moved, not for the fun of it, but because they had to. The terrain would be open savannah-type grassland in the tropics of East Africa.

 

While camped, each day the group would split up to forage for food. The women, children and old men went off in one party, foraging for roots, fruits, tubers, berries and easily caught bugs and animals. This party, on average covered about 5 miles. They leisurely walked and rested from time to time. After about four to five hours they were done. The children walked too and, a lot of the time, scampered about and chased each other as well as the lizards and beetles. Babes in arms of course were carried.

 

It is estimated that the average adult female energy expenditure was 600 kcal per day on physical activity. This compares to 230 kcal for today’s sedentary female office worker.

 

The able-bodied men went off, chiefly looking for small game, but would also be collecting other edible matter on an opportunistic basis. This party would cover more ground during the day - 9 to 12 miles on average. Part of the time they would be running or jogging, to chase and trail potential game. Most of the time, they too would be finished after about four to five hours. However on rarer occasions they may be away for as much as 48 hours tracking a wounded animal.

 

It is estimated that their daily expenditure of energy was over a 1,000 kcal. Compare this to the 306 kcal of the average sedentary male office worker.

 

There are therefore two patterns, one for each gender:

Females would pass their lives exercising to a moderate extent, and low intensity.

 

Males started their lives with the female pattern, graduated to the masculine pattern for most of their lives (vigorous and more sustained physical activity) and then tapered off to feminine levels again in old age.

 

How does this chime with what we know about human biology today? It fits very well. Evidence is that women do not need to exercise so long or so hard as men to maintain their health. Men need more vigorous physical activity to maintain health. From the world of track athletics we know that men are better built for endurance running.

 

What happened to our ancestors in old age? What is striking is that old people stayed physically active until their very last days. They were athletes right to the end. The end would come when they could no longer keep up with the group when it moved camp some 10 miles away. The infirm person would be left behind, propped up under a bush, to await the arrival of the jackals and other predators. In this harsh existence, there was no room for people who put the survival of the group at risk.

 

Just imagine how average life expectancy would drop today, if anyone who couldn’t walk 10 miles were left for dead!

 

So what are we to make of this? Everything we know about peoples or individuals who get this amount of physical activity demonstrates that, as a result, they have better health than they would otherwise have had. Note the qualification ‘than they would otherwise have had’. Exercise by itself is not enough. Other lifestyle activities can be even more important in determining good health, notably non-smoking and good eating habits.

 

The big question is, are there any vital body functions that depend on physical activity? Yes, indeed there are. Studies, going from those on bed-ridden people to astronauts, all point to a number of conditions brought about by a lack of physical activity. We are not like the bear for example that can stay immobile for 6 months (while hibernating) without suffering health consequences.

 

What are the consequences for human health then, of physical inactivity? Let’s look at some of them.

 

Exercise and Health Factors

Bone demineralisation and fractures

This condition is multi-faceted, but all the evidence suggests that regular physical activity improves bone structure, its volume and thereby resistance to fracture. Elderly women can benefit from as little as one hour per week of lower-intensity activity - 42% lower risk of hip fracture and 33% lower risk of vertebra fracture[1]. The rhythmic jolting associated with walking/jogging, excites the bone building cells (osteoblasts) into raising their tempo. In young people the bone builders work faster than the bone strippers and bone mass increases. Even in older people the bone builders will work harder and fall less far behind the bone strippers.

 

Rheumatism, arthritis and joint stiffness

Regular activity of the kind practised by our Pleistocene ancestors encouraged cartilage maintenance, lubrication and renewal of the wearing surfaces. Dysfunctional joints are due in large part to not giving them enough to do. If you don’t use it, you lose it!

 

Syndrome X

This is the collective name given to a quarto of ‘diseases of civilisation’: high blood pressure, coronary artery disease, obesity and diabetes. They all have a common link - high insulin levels. Yes, our old nemesis of insulin rears its ugly head. Low exercise levels mean that more insulin has to be secreted to handle a given glucose load. Result: more insulin floating around creating mischief. (See Chapter Five.) Exercise is essential to maintain optimum resistance to diabetes, obesity, hypertension and heart disease.

 

Lower leg circulation

There is an artery that passes through the ball of the foot. As you walk or run this artery gets alternately compressed and released. The general effect is that of a pump. Walking/running helps pump blood through the lower leg. Without it the lower leg gets poor circulation and is prone to deep vein thrombosis.

 

Are you one of those people who, after a little while sitting at a desk or table, find their knees jogging up and down? This too, is a natural reflex helping to maintain lower leg circulation.

 

Lymphatic circulation

As handmaiden to our blood circulation, we have a secondary system of circulation, known as the lymphatic system. This is responsible, in part, for transporting the products of digestion to other parts of the body; bringing immune system killer cells to parts of the body under attack and flushing away debris and toxic matter. Unlike the blood, which is pumped around the body by the heart, the lymphatic system does not have a pump of its own. It relies on the general flexing of muscles to do the job. Lack of physical activity means sluggish lymphatic circulation and a host of maladies linked to that.

 

Cosmetic reasons

We are all, every single one of us, descended in an unbroken chain of ancestors who have all successfully found a mate and reared their children. Couples who got together to have children and didn’t, failed for a number of reasons. Accidents, sickness, infertility all take their toll. But the bottom line is that they didn’t have any offspring.

 

It follows that we are descended from people who have been successful in having children. They were successful because they were lucky and because they were healthy. Not much can be done about luck, accidents and so on, but over the long term our ancestors will have been slightly better at picking healthy mates. We are programmed to recognise a healthy prospective mate. That, to a large extent, is the substance of the ‘chemistry’ that sparks between two people who are attracted to each other. ‘Looking good’ is an important part of successful human reproduction.

 

Even if you are not looking for a mate, ‘looking good’ gives pleasure to others. Film stars make their fortunes out of people’s hunger to cast their eyes on good looking people. The exact nature of the good looks changes with the mood of the times, but the fundamentals do not. No one is going to make it as a heart throb if they are giving off an air of general ill health. Glowing complexion, vibrant muscle tone and an energetic demeanour are attractive in their own right. We are genetically programmed to find them so.

 

Self preservation

In the world of our ancestors, they did a lot of walking and running because they had to. It was a matter of survival. It was the means by which they got their dinner. If they were unsuccessful in getting dinners they became dinner for another creature!

 

In today’s world such automatic sanctions for lack of physical fitness are rare. It is quite possible to live a lifetime as a couch potato and never be embarrassed by a situation where your physical abilities are found wanting. But just think about this: in an air crash, do you want to be the last one to get out of the emergency door?

 

Longevity

Recent, carefully controlled Finnish studies[2] over many years on identical twins have demonstrated what many people have long suspected, that physically fit people live longer than those who are not.

 

In this study, it was found that in any given period, ‘Sedentary’ people were 1.3 times as likely to die as the ‘occasional’ exercisers and nearly twice as likely to die as the ‘conditioning’ exercisers. The figures were the same for both men and women.

 

The exercise criteria were extremely modest

·      ‘Conditioning’ exercisers exercised for a minimum of 30 minutes, 6 times a month.

·      ‘Occasionals’ exercised even less than the ‘conditioners’ but did some regular exercise.

·      ‘Sedentary’ people claimed not to exercise at all.

 

We do not know the effect on longevity if regular physical activity is raised to the level of our prehistoric ancestors, but the suspicion has to be that it is yet further improved.

 

Stress, depression and mood

Anecdotal evidence is now confirmed by an understanding of human biochemistry. Physical exercise has a beneficial effect on a whole range of hormones that regulate mood.

 

Exercise modulates hormones that act on serotonin receptors helping to lift depression. It brakes the production of stress hormones such as cortisol and adrenaline. Reducing these two hormones not only reduces feelings of panic and stress, it also reduces the knock-on effect, production of insulin and all the damage that follows.

 

Finally, carried to an extreme, endurance runners reach a ‘high’ where their bodies are producing morphine-like substances, giving them a tremendous feeling of well-being.

 

Exercise is good to improve feelings of well-being.

 

 

Optimum Exercise Pattern

So just like for eating, it is possible to identify the most favourable pattern of exercise for human beings.

 

Having read the foregoing you will not be surprised to hear what the ideal level of physical activity is:

·      women, children and old men - walk five miles per day, every day.

·      able bodied men - walk and run 9 to 12 miles per day every day.

 

All the studies confirm that these exercise patterns are the optimum for good health. Indeed anyone doing that today is considered to have a high level of fitness. For our ancestors, it was just the norm for everyone.

 

But what are we to do in the modern world? For most of us it is just not practicable to spend four hours a day exercising. Is it really necessary to exercise so much? Are other forms of exercise more helpful?

 

The hard answer is that you get out what you put in. The good news is that the response is not linear. At the start you get a lot of benefit from a relatively small increase in exercise. As you increase the level, the benefits improve too, but not in proportion. It is the law of diminishing returns.

 

It is even possible to exercise too much. World class endurance athletes are more prone to infectious diseases. In addition, they distort their dietary habits for maximum performance - to the detriment of their health.

 

So what is a reasonable compromise between what is desirable and what is possible?

 

Exercise Essentials

We can put together the foregoing paleo-anthropological argument with the studies and recommendations made by various authorities.

 

The recommended physical activity is :

·      3 to 5 days per week of aerobic exercise at moderate to moderately high intensities.

·      20 to 60 minutes each session.

 

That is the laconic specification. Let us look at what that means in practise.

 

 

 Heart Rate:

Beats per Minute

Age

40% Max.

85% Max.

Max

20

80

170

200

30

75

160

190

40

70

150

180

50

70*

145

170

60

65*

135

160

70

60*

125

150

*Many older people will have a resting pulse greater than this.

‘Moderate intensity aerobic exercise’ is one that raises your heart rate to 40% of its maximum. Women, children and older men should aim to do this.

·      Examples of moderate physical activity include

walking, cycling, playing basketball or volleyball, swimming, water aerobics, dancing fast, pushing a stroller, raking leaves, shovelling snow, washing or waxing a car, washing windows or floors, gardening, golf and tennis.

 

‘Moderate to high intensity aerobic exercise’ is one that raises your heart rate to 85% of its maximum. Able-bodied males should aim to do this.

·      Examples of moderate to high intensity physical activity include

jogging/running, squash, hard swimming, vigorous cycling, manual labouring and weight training.

 

Don’t forget that the above are minimums! Nothing to stop a women playing squash if she wants, or indeed a centenarian jogging 10 miles if he is fit enough.

 

In today’s modern America, the problem is the opposite. Many children and young adults get out of breath just changing the channels on the remote control.

 

A word of warning. Anyone who has a history of smoking, is or has been severely overweight, is middle-aged or more, is under constant stress, has a family history of heart disease – should get a check up for potential problems. Advanced heart disease can have no symptoms. Even regular exercisers who fit into the above categories can be struck down without warning.

 

Jim Fixx, who wrote The Complete Book Of Running and thereby set off the jogging craze, was such a case. He had been a heavy smoker and had been very overweight He had a poor family history, his father dying of a heart attack at the age of 43. Fixx quit smoking, lost 50 pounds of surplus weight and started running 60 to 70 miles a week. Everything was all right for 15 years. Then at the age of 52 he suffered a massive heart attack while running and died. His coronary arteries were hopelessly blocked. They were almost certainly far gone when he started his fitness regimen, but he didn’t know - he had never had a check-up. And just being physically fit, contrary to what he thought, was not enough to stop his arteries getting worse. Rather, physical fitness is just one of the elements necessary to health and well being.

 

What about other forms of exercise? Callisthenics, muscle building, stretching and so on? Yes, they are all helpful. Indeed the recommendation is that everyone should be using stretching exercises at least three times a week. Elderly people are particularly recommended to do muscle building exercises and joint suppleness training every day. This will ensure that they arrest the loss of muscle mass and keep their joints flexible.

 

Savvy Exercising for Weight Loss

Many people exercise to lose weight. We can use a knowledge of our biochemistry to make sure this happens in the most efficient way.

 

When we exercise moderately (40% of max heart rate), then the source of energy that the body mostly uses comes from the triglyceride fats that are floating around in the blood stream. These are the fats that we want to burn! The body has to replace them from stores in the fat tissues.

 

If, however, we step up the exercise rate, then the body starts to prefer energy from carbohydrates stored in the liver, muscles and blood. The body will replace these later from what we eat.

 

The good news then, is that moderately intense exercise is better than high intensity exercise for fat reduction. This effect is particularly marked if no carbohydrates have been consumed before, during or after the exercise. So, go for your brisk, early morning walk on an empty stomach. Avoid all sugary drinks, and certainly don’t eat any bad carbohydrates. If you must eat during this period, restrict it to the ‘good’ foods, some low glycemic fruit for example. You won’t feel hungry. Less conventionally, don’t be inhibited by your cultural conditioning: it is quite possible to have a shrimp and vegetable stir-fry or a mixed salad for breakfast.

 

Nutrition for Competitive Sports

Eating in order to obtain maximum performance is the domain of specialised sports nutrition. The only reason for broaching this topic here is to make an important point: sports nutrition has, as its main objective, the achievement of maximum performance.

 

Eating for maximum performance is rarely in harmony with nutrition for optimum health.

 

Take one example: ‘carbohydrate loading’. This technique, to stoke up energy reserves before a race, makes extensive use of high glycemic index ‘bad carbohydrates’ that are consumed in a particular pattern over an extended number of days. To obtain maximum performance the technique is very good. But, this is exactly contrary to the principles of eating for good health.

 

This is a trade-off that is rarely explained to athletes: performance vs. long-term health.

 

Note too, that the ‘savvy eating for weight loss’ procedure explained earlier is the exact opposite to that prescribed for eating for endurance performance. For performance, athletes are recommended to consume high glycemic index foods (that is, bad carbohydrates) before, during and after the competition!

 

It is readily acknowledged by sports nutritionists that this causes hyperinsulinemia - and they know it wreaks havoc on arteries and scrambles hormonal responses. They know, too, that hyperinsulinemia locks up fat and makes it unavailable for burning by the muscles. This is a drawback. Nevertheless, the calculation they make is that this is the lesser of two evils - the greater energy surge from the bad carbohydrates outweighs the loss of energy generated from fat sources.

 

We have here an example of how food is used as a drug. A performance-enhancing drug for athletes. In various ways what and how you eat is having a drug-like effect on thousands of important bodily activities.

 

Lifestyle Practices

Not surprisingly, conventional wisdom is coming to the view that physical exercise should be more than just an episode on various days of the week. Physical exercise needs to be integrated into the everyday pattern of living.

 

First of all, try to develop hobbies, sports and interests that of themselves give you the base-load of exercise that you need. If you play golf one day a week, go dancing one day a week, do some gardening one day a week, and go swimming one day a week, then you are well on the way to being well exercised. By all means go to aerobics, play tennis, jog round the block too.

 

Next, take every opportunity to work out those muscles as you go about your day. Why stress yourself to find a parking space right next to the shopping mall entrance? That only helps to raise stress hormones with all the damage that that does. Park at a comfortable distance away and walk those extra 100 yards! Walk up the stairs instead of taking the elevator. Carry the shopping instead of pushing the trolley.

 

Today, we are so spoilt for labor-saving devices that we have, perversely, to seek out labor intensive activities or make them up for ourselves. Push yourself constantly to stretch your body’s physical capacity. Never take the easy way out when the opportunity is there to challenge your physical limits.

 


[1] Gregg et al; Ann Intern Med 1998;129:81-88,133-134.

[2] Kujala; [Exercise linked to longevity]; JAMA 1998;279:440-444.

 

 

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