There are many ways to measure Asia's remarkable economic progress over the past half-century, but you can't get more basic than this: starvation, for most of the region, has become a thing of the past. In 1943, India's Bengal famine killed more than 4 million people, and as recently as the early 1960s, tens of millions of Chinese died in the man-made famines of the Great Leap Forward. Just 25 years ago, the United Nations estimated that up to 40% of Asians were chronically undernourished. That number now stands at 16%. While people in countries such as North Korea, Cambodia and Bangladesh still struggle with malnutrition, hundreds of millions of other Asians who grew up amid scarcity now live in relative abundance. Barring catastrophe, most of their children will never know the pinch of real hunger.
And that's leading to a whole new problem. Asia's economic transformation has left many of its inhabitants with more food on their plate than they can healthily handle. The explosive growth of urbanization has dramatically cut rates of physical activity and introduced fat-laden foods of convenience to a new generation of Asians once accustomed to lean diets. The result has been a sharp upswing in obesity, a condition virtually unheard of in Asia a quarter of a century ago. In India, home to half of all undernourished people in the world, 55% of women between 20 and 69 years old are overweight, according to a recent study. A survey released last month by China's Ministry of Health found that the number of obese Chinese had doubled to 60 million between 1992 and 2002, while some 200 million are at least overweight; among children, the obesity rate has reached 8.1%. Altogether, the International Obesity Task Force, a global NGO that studies the spread of the epidemic, estimates that 1.7 billion people—one out of every five worldwide—are overweight or obese. "It's gone very quickly from that period when famine was receding," says Professor Barry Popkin, a nutrition expert at the University of North Carolina. "All of a sudden, instead of having a normal-weight body for a decade or two or three, you move from undernutrition to overnutrition in years."
Unlike the corpulent United States, it can be difficult to tell the extent of Asia's weight problem just by visiting your local fast-food franchise. Relatively few Asians have cracked the ranks of the obese; even technically overweight Asians, with their naturally small frames, can look slim compared with the average Westerner. But those seemingly svelte appearances can be deceiving. Doctors define overweight and obesity by a rough-and-ready measurement called the body mass index (BMI). For Westerners, a BMI above 25 is considered overweight, while one above 30 is obese. Yet studies have shown that Asians can suffer the ill effects of obesity at a much lower BMI; a World Health Organization (WHO) study has suggested that the threshold for Asians could be a BMI of 23 for overweight, and 26 for obesity. "In all likelihood, this means we have probably underestimated the effects of excess weight in a country like China," says Dr. Catherine Le Galés-Camus, a noncommunicable-diseases expert at the WHO.
It's not clear why Asians seem to show such a marked vulnerability to the effects of gaining weight. Some scientists theorize that children who are undernourished in the womb, which was not uncommon throughout much of Asia until recently, might develop unusually high levels of abdominal fat in adulthood if they're exposed to above-normal calorie levels. This puts them at greater risk for obesity-related illnesses like heart disease, cancer, hypertension and diabetes. India and China already have 32.7 million and 22.6 million diabetes sufferers, respectively; by 2030, the WHO forecasts, Asia could have as many as 190 million cases, with India and China having over 100 million between them. Asia's overburdened health-care systems will be struggling to cope. China, where 160 million people suffer from hypertension, is already feeling the strain, says Popkin: "You wait another decade and it's going to be very scary what it does to their health system."
Why is this happening? The obvious, almost trivial answer is that we eat too much high-calorie food and don't burn it off with enough exercise. Richer salaries have led to a richer diet; according to the U.N.'s Food and Agriculture Organization, meat consumption has more than doubled in China and India since the 1970s, while fat and sugar in the diet has also more than doubled since the 1980s. If only we could change those habits, the problem would go away. But clearly it isn't that easy. The growing diet and slimming industries in Asia have had no more success than their Western counterparts in checking the rise of obesity. Food and drug companies around the globe spend ever greater amounts of money trying to find a magic food or drug that will melt the weight away. Yet the world's collective waistline just keeps growing.
It's natural to try to find something to blame—fast-food joints or food manufacturers, or even ourselves for having too little willpower. But the ultimate reason for obesity may be rooted deep within our genes. Obedient to the inexorable laws of evolution, the human race adapted over millions of years to living in a world of scarcity, where it made biological sense to eat every good-tasting thing in sight when you could find it.
Although our physiology has stayed pretty much the same for the past 50,000 years or so, we have utterly transformed our environment. Over the past half-century especially, technology has largely removed physical exercise from day-to-day urban life. At the same time, it has filled store shelves with cheap, mass-produced, tasty food that is packed with calories. And technology has allowed advertisers to deliver constant, virtually irresistible messages that say "Eat this now" to everyone old enough to watch TV.
This artificial environment has increasingly spread from ground zero of the global fat crisis—the U.S.—to less developed countries. As Asian nations catch up economically and adopt more Western lifestyles, their problems with obesity have caught up, too. By contrast, among people who still live in conditions most like those of our distant Stone Age ancestors—such as the Maku or the Yanomami of Brazil—there is virtually no obesity at all.
And that's almost certainly the way it was during 99.9% of human evolution. For most of the 7 million years or so since we parted ways with chimps, life was very harsh—"poor, nasty, brutish and short," in Thomas Hobbes' memorable phrase. The average life expectancy was probably well under 30. But much of that dismal brevity could be chalked up to accidents, infections, traumatic childbirth and unfortunate encounters with saber-toothed cats and other such predators. If a Cro-Magnon, say, could get past these formidable obstacles, he might conceivably live into his 60s or even longer, with none of the obesity-related illnesses that plague modern humans.
Our earliest ancestors probably ate much as their cousins the apes did, foraging for fruits, shoots, nuts, tubers and other vegetation in the forests and savannas of Africa. Because most wild plants are relatively low in calories, it took constant work just to stay alive. Fruits, full of natural sugars like fructose and glucose, were an unusually concentrated source of energy, and the instinct to seek out and consume them evolved in many mammals long before humans ever arose. Fruit wasn't always available, but those who ate as much of it as possible when they could find it were more likely to survive and pass on their sweet tooth to their progeny.
Our love affair with sugar—and also with salt, another crucial but not always available part of the diet—goes back millions of years. But humanity's appetite for animal fat and protein is probably more recent. It was some 2.5 million years ago that our hominid ancestors developed a taste for meat. The fossil record shows that the human brain became markedly bigger and more complex about the same time. And indeed, according to Katherine Milton, an anthropologist at the University of California, Berkeley, "the incorporation of animal matter into the diet played an absolutely essential role in human evolution."
For starters, meat provided a concentrated source of protein, vitamins, minerals and fatty acids that helped our human ancestors grow taller. The first humans were the size of small chimps, but the bones of a Homo ergaster boy dating back about 1.5 million years suggest he could have stood more than 1.8 m as an adult. Besides building our bodies, says Emory University's Dr. S. Boyd Eaton, the fatty acids found in animal-based foods would have served as a powerful raw material for the growth of human brains.
Because it's so packed with nutrients, meat gave early humans a respite from constant feeding. Like lions and tigers, they didn't have to eat around the clock just to keep going. But more important, unlike the big cats, which rely mostly on strength and speed to bring down dinner, our ancestors depended on guile, organization and the social and technological skills made possible by their increasingly complex brains. Those who were smartest about hunting—and about gathering the plant foods they ate as part of their omnivorous diets—tended to be better fed and healthier than the competition. They were thus more likely to pass along their genes.
The new appetite for meat didn't mean we lost our passion for sweets, though. As Berkeley's Milton points out, the brain's growth may have been facilitated by abundant animal protein, but the brain operates on glucose, the sugar that serves as the major fuel for cellular function. "The brain drinks glucose 24 hours a day," she says. The sugars in fruit and the carbohydrates in edible grains and tubers are particularly good sources of glucose.
The appetite for meat and sweets was essential to human survival, but it didn't lead to obesity for several reasons. For one thing, the wild game our ancestors ate was high in protein but very low in fat—only about 4%, compared with up to 36% in grain-fed supermarket beef. For another, our ancestors couldn't count on a steady supply of any particular food. Hunters might bring down a deer or a rabbit or nothing at all. Fruit might be in season, or it might not. A chunk of honeycomb might have as many calories as half a dozen doughnuts, but you might be able to get it once a year at best—and it wouldn't have the fat.
Beyond that, hunting and gathering took enormous physical work. Chasing wild animals with spears and clubs was a marathon undertaking—and then you had to hack up the catch and lug it miles back to camp. Climbing trees to find nuts and fruit was hard work, too. In essence, early humans ate what amounted to the best of the high-protein diet and the low-fat diet, and worked out almost nonstop. To get a sense of their endurance, cardiovascular fitness, musculature and body fat, say evolutionary anthropologists, look at a modern marathon runner.
That was the condition of pretty much the entire human race when anatomically modern humans first arose, between 150,000 and 100,000 years ago, and things stayed that way until what some anthropologists have called humanity's worst mistake: the invention of agriculture. The ancient Chinese were among the first people to develop farming, growing rice along the banks of the Yangtze River. Nutritionally, the shift away from wild meat, fruits and vegetables to a diet mostly of cultivated grain robbed humans of many of the essential amino acids, vitamins and minerals they had thrived on. Average life span increased and population density exploded, thanks to the greater abundance of food, but average height diminished. Skeletons also began to show a jump in calcium deficiency, anemia, bad teeth and bacterial infections. Most meat that people ate came from domesticated animals, which have more fat than wild game. Livestock also supplied early pastoralists with milk products, which are full of artery-clogging butterfat. But obesity wasn't a problem, because even with animals to help, physical exertion was built into just about everyone's life—as can still be seen in the most rural areas in Asia.
That remained the case practically up to the present. It's really only in the past 100 years that cars and other machinery have dramatically reduced the need for physical labor—in many parts of Asia, those technological changes are even more recent. And while exercise has vanished from everyday life, the technology of food production has become much more sophisticated. In 1700, Britain consumed almost 21,000 tons of sugar. That was about 3.4 kg of sugar per capita. The global consumption of sugar is now some 46 kg per capita. Farmers armed with powerful fertilizers and high-tech equipment are growing enormous quantities of corn, wheat and rice, most of which is processed and refined to be tastier and more convenient but is less nutritious. They are raising vast herds of cattle whose meat is laden with the fat that makes it taste so good. They are producing milk, butter and cheese by the tankerload, again full of the fat that humans crave. And thanks to mass production, all that food is relatively cheap.
For Asians, the rapid shift from undernutrition to caloric overdrive is especially fraught with risk. Some scientists believe that many Asian populations, particularly South Asians, evolved a so-called "starving gene" after living for thousands of years under near-famine conditions. That may have left them with bodies that are paradoxically too metabolically efficient to deal with the relative abundance of modern life. "It's a genetic trait that benefited them in the past when food was often scarce, but when food is plentiful all the time, it becomes detrimental," says Professor Brian Tomlinson of the Chinese University of Hong Kong.
There's no doubt that the obesity epidemic is real and our collective metabolic health has been getting progressively worse. Indeed, says Yale public-health expert Dr. David Katz, "today's kids may be the first generation in history whose life expectancy is projected to be less than that of their parents." But there's plenty of reason for hope. Researchers are hard at work trying to understand the basic biochemistry of hunger and fat metabolism; countries such as Singapore are finding success in actively fighting the rise of obesity; and Asians in general are beginning to wake up to the importance of healthy diets and regular exercise. The WHO World Health Assembly recently passed a landmark global strategy on diet and physical activity that aims to help member countries combat the growing and expensive burden of obesity-related noncommunicable diseases.
In the past, campaigns against infectious diseases and other enemies of public health have dramatically improved the quality of life throughout Asia. Now, a region that had trouble feeding itself just 50 years ago must battle the unintended effects of its amazing economic success. To win this war will require nothing less than conquering millions of years of evolution.