How’s this for a not-so-sweet surprise: despite marketing to the contrary by the corn industry, high-fructose corn syrup (HFCS) does indeed cause more weight gain than sugar, according to a new study cited by Science Daily.

Princeton University researchers found that rats got fatter eating HFCS than when eating sugar, even when overall caloric intake was the same, and also accumulated abnormal fat deposits in the abdominal area. Circulating blood fats called triglicerides rose as well.

In the first experiment, one group of male rats was given the same concentration of sugar found in soft drinks, while another group received a high-fructose corn syrup solution that was half as concentrated.

“When rats are drinking high-fructose corn syrup at levels well below those in soda pop, they're becoming obese — every single one, across the board. Even when rats are fed a high-fat diet, you don't see this; they don't all gain extra weight,” professor Bart Hoebel told Science Daily.

The second experiment studied weight gain, body fat and triglyceride levels in rats that were consuming high-fructose corn syrup over a period of six months.

These rats showed symptoms of what’s known as metabolic syndrome in humans, gaining 48 percent more weight than rats eating a normal diet of rat chow. The team’s next step is to discover exactly why this is happening.

"These rats aren't just getting fat; they're demonstrating characteristics of obesity, including substantial increases in abdominal fat and circulating triglycerides," study participant and Princeton graduate student Miriam Bocarsly explained, adding that these characteristics are associated with high blood pressure, coronary artery disease, cancer and diabetes in humans.

Critics have long claimed that high-fructose corn syrup promotes obesity, pointing to the significant thickening of Americans’ midsections over three decades — a period that corresponds with increased usage of HFCS. Each American consumes an average of 60 pounds of high-fructose corn syrup every year.

The Corn Refiners Association released a statement titled “Gross Errors in Princeton Animal Study on Obesity and High Fructose Corn Syrup: Research in Humans Discredits Princeton Study” in response to the Princeton study, claiming that the results in rats don’t have significant meaning for humans.