High-fructose corn syrup is a ubiquitous sweetener used in processed foods, not only as a sweetener, but also a preservative, browning agent and a host of other things. It has come under a hailstorm of criticism since the mid-2000s, as scientists have linked it to health problems, ranging from from fatty liver disease to hypertension. However, no association has been more sinister and compelling in news reports than the one between high-fructose corn syrup and obesity. Scientists say your body and brain simply don't respond to high-fructose corn syrup with typical satiety cues. That is, it doesn't produce a sense of fullness and diminish your appetite in the way that other foods do. The consequence, as some scientists tell it, is massive overeating and unprecedented weight gain.
About High-Fructose Corn Syrup
High-fructose corn syrup became a popular alternative to sugar in the 1970s and has since become a dominating ingredient in American food and drink products because of its low cost, ease of production and widespread availability. A researcher reported in the "American Journal of Clinical Nutrition" that no other single ingredient in the history of American food processing has seen the percent increase in use --- more than 1,000 percent in 20 years --- that high-fructose corn syrup has. Not lost on those in the scientific community, however, is that waistlines have burgeoned along with the use of high-fructose corn syrup. America's obesity and diabetes twin epidemics seem to have paralleled high-fructose corn syrup's popularity, leading to research on the sweetener's effect on eating habits, like satiety.
High-Fructose Corn Syrup and Satiety
High-fructose corn syrup, as the name suggests, is a mixture of sweeteners. There are several formulations, but to earn the name, there's generally more fructose than glucose or other sugar. Common ratios are 55:45 and 90:10. In "YOU: On a Diet," Drs. Michael Roizen and Mehmet Oz explain that fructose isn't metabolized the same way as other food. They say it isn't even seen as food by your body. As a result, your brain doesn't get the cues that you've had enough food and drink, and you probably won't experience satiety, even though you've consumed many calories. Added sugars like high-fructose corn syrup make up roughly 16 percent of all calories Americans consume, according to the Dietary Guidelines for Americans 2010. So when you consume high-fructose corn syrup, you may be more likely to overeat.
Leptin and Satiety
Leptin is a protein hormone that is secreted by your fat cells while you sleep. It was discovered in 1994 by Rockefeller University researchers in animal studies. Scientists are still making discoveries about how leptin works. What's known for sure is that it is one of many systems designed to seek homeostasis in your body. That means your body naturally strives to achieve a balance between calories in and calories out. Specifically, leptin binds with receptors in the hypothalamus region of your brain, where it tells you to stop eating after a meal. It says, "I've had enough," and dials back your appetite. That's satiety. In addition, leptin senses excess stored energy in your body and can make your body burn more calories.
Research Review
In a review of research, George Bray and colleagues at Louisiana State University found fructose doesn't trip the leptin sensor or promote enhanced production of leptin. In addition, after consuming high-fructose corn syrup, participants of some studies had reduced leptin concentrations. Other sweeteners, like glucose, provide satiety signals to the brain that fructose cannot provide, because it is not transported into the brain. In an animal study, a diet high in high-fructose corn syrup led to leptin resistance. This causes cells to stop accepting leptin's messages, regardless of how much leptin you have in your body. In both study sets, the results were significant weight gain and habitual consumption of more calories.
References
- "American Journal of Clinical Nutrition"; Consumption of High-Fructose Corn Syrup in Beverages May Play a Role in the Epidemic of Obesity; George A. Bray, et al.; April 2004
- "YOU: On a Diet: The Owner's Manual for Waist Management"; Michael F. Roizen and Mehmet C. Oz; 2006
- USDA: Dietary Guidelines for Americans 2010
- "Harvard Mahoney Neuroscience Institute Letter"; Leptin and the Control of Body Weight; David Dressler and Huntington Potter; Spring 1997
- "American Journal of Physiology"; Fructose-Induced Leptin Resistance Exacerbates Weight Gain In Response To Subsequent High-Fat Feeding; Alexandra Shapiro et al.; August 2008
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