An overweight America may be fixated on fat and obsessed with carbs but nutritionists say the real problem is much sweeter -- we're awash in sugar.

Not just any sugar but high fructose corn syrup.

The country eats more sweetener made from corn than from sugarcane or beets gulping it down in drinks as well as in frozen food and baked goods. Even ketchup is laced with it.

Almost all nutritionists finger high fructose corn syrup consumption as a major culprit in the nation's obesity crisis. The inexpensive sweetener flooded the American food supply in the early 1980s just about the time the nation's obesity rate started its unprecedented climb.

The question is why did it make us so fat. Is it simply the Big Gulp syndrome -- that we're eating too many empty calories in ever-increasing portion sizes? Or does the fructose in all that corn syrup do something more insidious -- literally short-wire our metabolism and force us to gain weight?

The debate can divide a group of nutritional researchers almost as fast as whether the low-carb craze is fact or fad.

Loading high fructose corn syrup into increasingly larger portions of soda and processed food has packed more calories into us and more money into food processing companies say nutritionists and food activists. But some health experts argue that the issue is bigger than mere calories. The theory goes like this: The body processes the fructose in high fructose corn syrup differently than it does old-fashioned cane or beet sugar which in turn alters the way metabolic-regulating hormones function. It also forces the liver to kick more fat out into the bloodstream.

The end result is that our bodies are essentially tricked into wanting to eat more and at the same time we are storing more fat.

"One of the issues is the ease with which you can consume this stuff" says Carol Porter director of nutrition and food services at UC San Francisco. "It's not that fructose itself is so bad but they put it in so much food that you consume so much of it without knowing it."

A single 12-ounce can of soda has as much as 13 teaspoons of sugar in the form of high fructose corn syrup. And because the amount of soda we drink has more than doubled since 1970 to about 56 gallons per person a year so has the amount of high fructose corn syrup we take in. In 2001 we consumed almost 63 pounds of it according to the U.S. Department of Agriculture.