While the food and beverage industry would like to convince us otherwise, research shows what many of us already knew: High fructose corn syrup (HFCS) is bad for your health. And while it’s true many of us simply consume too much sugar in general, HFCS seems to be worse than normal sugar. Not only does it appear to make you gain more weight, calorie for calorie, but it also leaves you hungrier than if you eat regular sugar.

All sugars are not created equal

Sucrose, or table sugar, is made up of glucose and fructose in equal parts–50 percent glucose, 50 percent fructose. High-fructose corn syrup is advertised as being 55 percent fructose, which isn’t a huge difference and therefore, should theoretically have just a small effect on hunger. However, there’s evidence that the advertised fructose-to-glucose ratio may not be the actual ratio.

A study by the Childhood Obesity Foundation found that very few HFCS-sweetened drinks contained only 55 percent fructose. In fact, most of them had fructose levels of around 65 percent. That might not sound like a significant difference, but in a 12-ounce can of soda this amounts to an additional teaspoon of fructose. Another study, published in the journal Metabolism, found that our bodies actually absorb more fructose from HFCS than we do from table sugar. This has serious implications.

Your body doesn’t know it’s full

Your body metabolizes sugars in different ways. When you eat table sugar, it’s processed in the intestinal tract, where it’s broken down into glucose, causing blood sugar levels to rise. When your blood glucose level hits a certain point, your body releases insulin. As insulin levels rise, your body releases a second hormone, leptin, which signals your brain that you’re full and don’t need to eat anymore.

On the other hand, fructose isn’t processed in the intestinal tract; it’s processed by the liver. It isn’t converted to glucose, and it doesn’t raise blood sugar like glucose does. And since it doesn’t raise blood sugar, your body doesn’t release insulin or leptin–and your brain doesn’t get the signal that you’re full. This can leave you feeling hungry even after you’ve consumed a lot of calories from fructose.

Fructose occurs in natural sources of sugar like fruit, but in doses too small to affect your appetite. HFCS-sweetened foods and drinks are a different story. They contain many times the amount of fructose that you get from eating fruits and that your body is well-equipped to handle. And since high-fructose corn syrup is an ingredient in practically every food that doesn’t come straight from the garden, you may be eating more of it than you think.

Sources:
http://goranlab.com/pdf/Ventura%20Obesity%202010-sugary%20beverages.pdf
http://www.ncbi.nlm.nih.gov/pubmed/25988134
http://blogs.scientificamerican.com/observations/how-corn-syrup-might-be-making-us-hungry-and-fat/
http://www.health.harvard.edu/blog/is-fructose-bad-for-you-201104262425