100 Million Years of Food (25 page)

A key factor may be physical
inactivity.
Prolonged stretches of watching TV, sitting down, and commuting by car have deleterious long-term health effects, including weight gain and diabetes. Our ancestors rarely spent prolonged periods being immobile; they couldn't, because that would have meant starvation, thirst, loneliness, etc. Instead, they were highly mobile; contemporary hunter-gatherers cover around 8.8 miles (men) or 5.9 miles (women) on foot each day.
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By contrast, the average American walks about 2.5 miles each day. The things that are done instead of walking—watching TV, sitting at a desk, and driving—are all associated with obesity, disease, and early death. Watching television is associated with an increased risk of obesity, type 2 diabetes, cardiovascular disease, and outright dying. The average American now watches nearly five hours of television a day. Each two-hour increment in watching TV translates into a 23 percent increase in the risk of obesity, a 14 percent increase in the risk of diabetes, a 15 percent increased risk of cardiovascular disease, and a 13 percent increased risk of dying.
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Working while sitting, as in desk or computer jobs, had less drastic but still unfortunate consequences, with each two-hour increment being associated with a 5 percent increase in the likelihood of obesity and a 7 percent increase in diabetes. By contrast, one hour per day of brisk walking is associated with a decrease in the likelihood of obesity by 24 percent and diabetes by 34 percent.
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Cars are also problematic. In an Australian study, people who commuted by car gained 4.8 pounds over four years, compared to 2.8 pounds for non-car-commuters.
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Long-haul truck drivers have an especially tough problem with obesity: The obesity rate (BMI 30 and above) among them is 69 percent, compared to 31 percent among the general population.
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The same problems afflict our pets: Dogs and cats that have to deal with living indoors, living in apartments, and being physically inactive also end up overweight and diabetic.

Now, some readers at this point will object: What is it about physical inactivity—watching TV, driving, and, for dogs and cats, being stuck all day indoors—that's so harmful? Didn't I just claim earlier that lowered energy expenditures are not to blame for the epidemic in obesity?

Several researchers have suggested that part of the reason that our pets are getting more obese is that their lives are boring; psychologists have also noted a connection between human obesity and boredom. Also, obesity rates are high in “boring” jobs that involve a lot of monotony (like driving trucks, cleaning buildings, factory work, and even construction jobs) and low in occupations that might seem sedentary but are intellectually stimulating (professors, teachers, artists). The usual claim is that the connection between boredom and obesity lies in stress, but stress is a tricky thing to define and measure. Who lives the more stressful life: a homeless person, a business executive with shareholders to placate, or a housewife burdened with social isolation and a philandering husband? Moreover, no matter how stress is defined, it has no consistent relationship with overeating.

Thus stress is not a helpful concept in understanding obesity. Rather, a key issue may be how energy is allocated within our bodies. Energy can be stored in fat cells, but it can also be used in powering the brain. People who have higher IQs and more education are at lower risk of becoming obese. It could be argued that highly educated people are less obese because they learn in college that low-fat foods are less fattening; however, groups like the Maasai traditionally ate a lot of fat in their diet but remained thin, and public perception about dietary fat and getting fat is not exactly a secret hidden in college campuses. Another argument about education and obesity is that the same willpower that gets people through college can also be applied to resisting tempting foods, but as pointed out earlier, obesity is not a problem of overeating; our lean hunter-gatherer ancestors ate about as much as we do today and expended about the same amount of energy.

An alternative explanation for the link between intellectual activity, boredom, and obesity is that the energy that could be channeled toward fat cells may instead be channeled toward fueling the brain,
if
the brain is occupied with challenging tasks.
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When we engage in mind-stumping tasks, our glucose levels drop. In other words, “mental effort” is more than a metaphor; it takes energy to reason intensely. That's why glucose drinks and breakfasts improve mental functioning, even for dogs.
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As societies have become more peaceful and orderly over the decades and centuries, the day-to-day drama of finding food and a place to sleep at night and avoiding predators and disease has been eliminated and replaced by the safe but predictable routine of television, cars, computers, offices, factories, shopping malls, supermarkets, stationary bikes, and treadmills. Being free from the threat of assault and disease is a remarkable step forward for our species. However, the challenge of surviving in the wild has been replaced by the challenge of trying to stay awake amid maddening drudgery, and all of this drudgery may mean fewer calories getting used by our brains and more ending up stored in our fat cells. Indoor dogs and cats and not a few zoo animals might express the same regret, if they could only speak.

Other factors that may influence obesity include hormones, antibiotics, and birth control. It has been observed that pets that are neutered are at greater risk of putting on fat; with humans, men who have less testosterone and women who have less estrogen are at greater risk of becoming obese.
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Children who are delivered via Cesarean section or who use antibiotics may have an increased chance of weight gain because of alterations in their gut-microbe community. (Although the exact mechanisms are still being worked out, farmers have routinely exploited the fattening effect of antibiotics to increase the weight of their domestic animals.
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) The precise details regarding the links between obesity, hormones, and antibiotics are still being worked out.

This brings up a fascinating paradox. Several studies have found that people who are slightly overweight, with BMI from 25 to 30, tend to live longer than people who are considered to be normal weight (BMI from 18.5 to 25) or obese (BMI 30 or greater). Part of the reason may be that sick people and smokers tend to be thinner, but even after controlling for such possibilities, the overweight-longevity paradox remains.
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There are at least two possibilities why being overweight may be healthier than being “normal” weight. Chronic diseases tend to result in loss of weight, muscle, and bone mineral density. Also, fat could help sequester and buffer the effects of toxins.
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Apart from the question of the ideal body type for long life or good health, there's another important consideration that influences many people: What's the ideal body type in the eyes of those we wish to attract? A surprising and perhaps disturbing conclusion from this research is that we tend to overshoot on our estimates of what it takes to look beautiful. According to studies of American college students, men want to be more muscular and bigger than women actually prefer; conversely, women want to be smaller, shorter, and more toned and have longer hair and bigger breasts than men actually prefer. What's going on? Why do we go through all this madness of trying to adjust our appearance if our partners are really not happy with the results?
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There are two possible explanations. The first possibility is that the important thing might not be the end objective; it might be more important for us to just have a strongly motivating goal in mind. If you are looking to attract a particular type of person, then having an exaggerated notion of the ideal body may be the simplest option available for achieving that goal.

A second, more likely explanation was offered by three of my colleagues at UCLA, David A. Frederick, Daniel M. T. Fessler, and Martie G. Haselton. They reasoned that a runaway competition for prestige takes place whenever we think about bodily characteristics and compare ourselves to others. We try to outdo others—that's human nature. Never mind what someone else wants; that's a pretty tough one to figure out, as any couple can attest. Just go one better than your peers, or imitate the most popular and richest public figure you admire, and you'll have an easy guide. Some Hollywood starlet wears fur boots and oversized shades and dyes her hair blond? Some Hollywood actor pulls off his shirt to reveal razor-cut abs? Got it. Such efforts might not be exactly what our partners want, but our minds are designed to make us compete against our peers in a silly but intrinsically human game of envy and status-seeking.
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*   *   *

The Greek island of Ikaria is famous for having some of the longest-living people in the world. Is this due to their diet or something else? To get a better sense of how Ikarians achieve their longevity, I catch a ferry from Athens to Ikaria, just off the shores of Turkey. My Ikarian friend George is an easygoing guy, quick to grin, always willing to chat, never in a hurry. He works at a grocery store. He wears no watch. During one visit to his store, George confides his wisdom to me, the key to Ikarian long life: “Great food. Great wine. Great sex.” I ask him to repeat it. He obliges: “Great food. Great wine. Great sex.” I heard him the first time, but he has an expression that I can't read, something between joy and absolute contentment—the ingredients to long life. After George and I run out of things to talk about—and after I get anxious about time spent away from my writing duties—George rings up my purchases: bread crisps, lentils, broad beans, chickpeas, cucumber. I take the road back to my hotel, a narrow lane hugging a cliff, the restless sea surging below.

Many people have visited Ikaria to learn about the secrets to long life.
National Geographic
has been here, a slew of scientists, Oprah's crew, all wanting to know how the people here live to such a ripe old age. The Ikarians I talk to dismiss the idea that their diet is the key to longevity. The real reason: no stress. The favorite saying on this island is “Don't worry.” People talk slowly here. No rush, no worries. The magic works wonders on me. Every morning, I wake up beaming. Crisp air, bright sky, glimmering ocean.

One afternoon, I walk into a restaurant in Ikaria to return a glass bowl that had been lent to me. There are four ladies at a table, smoking and chatting. I often see them in the restaurant at this hour; by the dock, groups of men are also chatting, waving their hands like orchestra conductors, drinking coffee or the local brew, ouzo. The ladies ask me when I am leaving Ikaria. “Tomorrow,” I reply.

The owner of the restaurant points to an “Ikarian Clock” on the wall. The clock has no hands.

All day, I have felt anxious about not getting work done, about not being able to make enough contacts or friends on the island, about money worries. I searched for flights and ferries out of Ikaria, ways of getting to a library, so I could push ahead with my schedule. After I see the Ikarian clock, though, something in me clicks. There is something extremely inviting about a land where time doesn't dictate your life.

I ask a young filmmaker on the island if she has eaten dinner. It is after 6:00
P.M
. She laughs exuberantly, as if I just delivered the best punch line she has heard in ages. Dinner? She hasn't eaten lunch by that point. What's the rush?

Perhaps I won't be leaving the next day after all. Some things can wait … can't they?

*   *   *

If the Mediterranean diet is the gold standard of Western nutrition, then the Cretan diet is the pinnacle. The famed traditional Cretan diet was based on bread made from wheat and barley, tomatoes, dandelions and other mountain greens, cabbages, eggplant, okra, leeks, onions, radishes, olives, grapes, the “poor man's meats” (beans, peas, lentils, chestnuts, almonds, walnuts, and peanuts), some goat and lamb, fish, goat cheese, snails, and copious olive oil and red wine. Cretans had notably longer life spans than other citizens in the Mediterranean Basin. However, Cretans complained that their olive-oil-based diet left them hungry; 72 percent of families surveyed in 1948 mentioned meat as their favored dish.
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During the following decades the Cretan people made good on their unfulfilled wishes. By 2010, the average middle-aged Cretan man ate around four times as much meat, almost twice as much pasta, and half the amount of olive oil and bread.
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He was a spindly 139 pounds in 1965, but in 2010 he weighed around 183 pounds. (Cretan women are even more obese).
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The rate of type 2 diabetes also spiked.
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Paradoxically, Cretan men may eat
fewer
calories per day now than in the 1960s, due primarily to reduced use of calorie-rich olive oil.
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If we wish to recommend the Cretan Mediterranean diet as the best, we should understand why Cretans were eager to abandon their traditional diet and why obesity rates were quick to jump upward despite the reduction in calories.

As a first guess, you might think that driving and the mechanization of farm work have cut back on the physical demands of Cretan farmers. After all, they used to burn more than 3,000 kcal per day on the job, but many Cretans now lead a sedentary lifestyle.
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The reduction in physical activity could certainly be a major factor in burgeoning Cretan waistlines. However, Greek children living in rural areas are generally more obese than city kids, even though rural kids are also more physically active and more fit, by measures of running, jumping, throwing, and so on.
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As previously mentioned, the key to obesity does not necessarily lie in energy intake or usage; rather, the answer may lie in physical inactivity, TV, cars, and boredom. Crete, in particular, went from being a place where walking and riding donkeys was the norm to something like a Grand Prix race circuit, with cars zooming madly from village to village, despite the compactness of the island.