HFCS and sucrose (table sugar) are both compounds that contain the simple sugars fructose and glucose, but there at least two distinct differences between them. First, sucrose is comprised of equal parts fructose and glucose (50/50), while typical HFCS has an uneven ratio, usually about 55 percent fructose and 42 percent glucose. Larger sugar molecules called higher saccharides make up the remaining 3 percent of HFCS. Second, because of the manufacturing process for HFCS, the fructose molecules in the sweetener are free and unbound, ready for absorption and utilization. In contrast, every fructose molecule in sucrose that comes from cane sugar or beet sugar is bound to a corresponding glucose molecule and must go through an extra metabolic step before it can be utilized.
The critical differences in appetite, metabolism and gene expression that underlie this phenomenon are yet to be discovered, but may relate to the fact that excess fructose is being metabolized to produce fat, while glucose is largely being processed for energy or stored as a carbohydrate, called glycogen, in the liver and muscles.
According to the Princeton press release for the study, in the 40 years since the introduction of high-fructose corn syrup as a cost-effective sweetener in the American diet, rates of obesity in the U.S. have skyrocketed. In 1970, around 15 percent of the U.S. population met the definition for obesity; today, roughly one-third of the American adults are considered obese, the CDC reported. High-fructose corn syrup is found in a wide range of foods and beverages, including fruit juice, soda, cereal, bread, yogurt, ketchup and mayonnaise. On average, Americans consume 60 pounds of the sweetener per person every year.
For more on HFCS, see Sugar: The New Health Food?