HARDLY a day goes by without some further revelation about the disturbing state of childhood obesity—and the diseases of old age that teenagers are beginning to suffer from. One recent study, published in the Financial Times on May 16th, found that the number of American children taking medication for the type of diabetes normally found in ageing obese people had more than doubled between 2001 and 2005. A worrying percentage of them were also taking drugs for such chronic conditions as hypertension and high cholesterol as well as type 2 diabetes.

The latest figures suggest that a third of American children are either overweight or at risk of becoming so. If the trend continues, today's children will be the first generation of Americans to have a shorter lifespan (by two to five years) than their parents. The life expectancy of Americans today is 77.6 years, one of the lowest in the developed world.

While most people concerned about their weight fixate on fats and carbohydrates, nutritionists say the real problem is sugar. And not just any old sugar, but the high fructose corn syrup (HFCS) that has replaced cane and beet sugar in processed foods and soft drinks over the past 25 years.

Nowadays everything from bread, pastries and breakfast cereals to yogurt, ketchup, candy and coke contain large dollops of HFCS. The food industry uses blends of 90% fructose and 10% glucose for baked goods and 55% fructose and 45% glucose for soft drinks. Fructose is about twice as sweet as table sugar.

For that, thank Japanese food technologists, who in the 1970s perfected a reliable way of turning corn starch into syrup sweet enough to become a sugar substitute. That happened at a time when over-generous farm subsidies in America had created a glut of corn. Then, in 1982, when the American government slapped import quotas on foreign supplies of cane and beet sugar, the American food industry promptly switched to cheap HFCS derived from subsidised domestic corn.

Since then, the annual consumption of HFCS in America has gone from nothing to more than 40 pounds (18.2 kg) per person. Today it accounts for nearly half of all the sugar and sweeteners used in the country. Nutritionists recommend no more than 10 to 12 teaspoonfuls of added sugar of all sorts a day. Instead, the average American's daily dose is more like 35 teaspoonfuls—most of it coming from soft drinks. A single 12-ounce can of pop contains the equivalent of 13 teaspoonfuls of sugar in the form of HFCS.

Meanwhile, the number of Americans with metabolic syndrome (MetS) has more than doubled. The syndrome—a condition characterised by obesity, insulin resistance and lots of ugly triglyceride fats in the blood—is linked to type 2 diabetes and cardiovascular disease. In Europe, where HFCS can't compete with cheap cane or beet sugar, only 15% of the adult population has MetS. In America, a staggering 33% suffers from the condition.

Taking a leaf from tobacco's book, the food industry has flexed its financial and political muscles to disprove any connection between fructose and obesity. But just like tobacco before it, the food industry is finding those implied links harder to deny. Studies identifying the causal mechanisms are cropping up increasingly in scientific literature.

Fructose apparently tricks the brain into thinking you are hungrier than you actually are. Unlike carbohydrates made up of glucose, fructose does not stimulate the pancreas into producing insulin. Nor does it promote the production of leptin, a hormone made by fat cells. Under normal conditions, the amount of insulin and leptin in the body signal to the brain that you've had enough to eat. Meanwhile, fructose doesn't seem to suppress the production of ghrelin, the hormone that triggers appetite, which normally declines after eating.


It's not that the fructose itself is bad for you. After all, that's what you get from eating fruit. But there's just so much of it around these days that it's hard to avoid consuming it to excess. Research shows clearly that, like cholesterol, there are good sugars and bad sugars. All of them pack a hefty calorific punch. What is needed, of course, is a recommended daily allowance for sugar to be included on all food labels (along with fat, carbohydrate, protein, cholesterol and sodium). The last time consumer groups tried to make that happen, the food lobby stopped them in their tracks.

But ponder this. Misguided government policy caused the food industry to switch to high fructose corn syrup in the first place. Another misguided government policy—America's plan to produce 35 billion gallons of alternative fuels annually, mostly in the form of bioethanol made from corn—could make the food industry switch back to healthier sugars just as fast.

UPDATE: Some points in this article have been disputed by a corn industry trade association. See the association's letter in The inbox. Two corrections have been made to the piece since it was first published. It is fructose alone, not high-fructose corn syrup, which is twice as sweet as sugar; and fructose consumption per head in America is close to 40 pounds a year, not 65 pounds.