Why the new study on high-fructose corn syrup and weight gain is flawed

By: Nicci Micco  |  Friday, March 26, 2010
This week I noticed many news media outlets were reporting that high-fructose corn syrup causes more weight gain than sugar does. The study everyone is referring to is out of Princeton and reported that rats given access to high-fructose corn syrup gained significantly more weight than those exposed to table sugar, even when they consumed the same number of calories overall. My first reaction was, “Oh no! Had we gotten it all wrong?” In May 2009, EatingWell did a comprehensive report on high-fructose corn syrup (HFCS), found in many processed foods, particularly in sweetened beverages. Then, after talking with top-notch nutrition researchers about everything from whether HFCS makes you hungrier to whether it makes kids hyper, we concluded the following:
To date, the research suggests that high-fructose corn syrup and table sugar aren’t that different: they’re both processed sweeteners that add “empty” calories to our diets. Our bodies seem to treat them the same way. At EatingWell, we try to limit sweeteners of any kind in recipes. Whenever possible, we use ingredients that don’t contain HFCS.

All of the published research available—and hours of interviews with experts who studied HFCS—led us to this conclusion. But perhaps this Princeton report was turning all that previous research on its head? If it did turn out that HFCS does, indeed, affect metabolism in ways that causes us to gain weight, I wanted to let our readers know as soon as possible. To help us interpret the research, I contacted Karen Teff, Ph.D., a physiologist at the Monell Chemical Senses Center in Philadelphia who has studied the issue extensively. She told us, “This study is poorly designed and poorly controlled and does not prove or even suggest that HFCS is more likely to lead to obesity than sucrose [table sugar].”
Teff offers the following: 1) this study does not provide evidence that HFCS is more likely to lead to obesity than sucrose, and 2) has no applicability to humans. She also emphasizes that one thing we can all take away from this is that “sweetened, caloric beverages should not be part of the daily diet.” (Need another reason to quit soda? Find out what it’s doing to your body here.) Teff went on to say, “Water or milk, which is nutritive and contains vitamins, are the beverages of choice.” (How much water do you really need? Find out here.)
Here’s why she came to her conclusions:
• The solutions of HFCS and sucrose used in all the studies—there were a few—in the Princeton report provided different levels of calories. (The HFCS, in fact, was lower in calories.)
• In one of the studies, the authors reported that male rats had a higher body weight after being exposed to 12 hours of access to the HFCS plus their typical rat chow compared to 1) standard chow alone, 2) 12 hours of access to sucrose with chow, and 3) 24 hours of access to sucrose with chow. However, they did not report or do the statistics on the change in weight. Thus, this is meaningless and poorly controlled.
• In a second experiment, they compared chow to chow-plus-HFCS for 24 hours and chow-plus-HFCS for 12 hours and found that access to the HFCS increased body weight. So what? Again, meaningless. This is like taking two groups of people, giving them the same diet but allowing one group to drink sweetened soda whenever they liked. Of course, they will gain weight because they are ingesting more calories. These findings have nothing to do with the controversy between sucrose and high-fructose corn syrup.
• Finally, in a third study, they show body weight as a percent of baseline (this is appropriate) and show that rats who had free access to both chow and HFCS gained a tiny bit more weight than chow alone, 12 hours of HFCS or 12 hours of sucrose. They did not compare it to the control of 24 hours of access to sucrose.
Editor's note: Study author Bart Hoebel, Ph.D., professor of psychology at Princeton University, responded to our blog on 4/1/10 in the .