Here’s a quick question: How many spoonfuls of high-fructose corn syrup did you eat yesterday?

Oh, you don’t recall slurping down any of the hyper-sweet corn extract? Well, you did—about eight teaspoons’ worth, according to the U.S. Department of Agriculture. In fact, the average American consumed 27 pounds of the stuff last year.

But while 8 teaspoons of artificially manufactured syrup may seem like an awful lot, it’s only a drop in the sugar bucket. The USDA’s most recent figures find that Americans consume, on average, about 32 teaspoons of added sugar every single day. That sugar comes to us in the form of candies, ice cream and other desserts, yes. But the most troubling sugar of all isn’t the added sugar we consume on purpose; it’s the stuff we don’t even know we’re eating.

In recent years, the medical community has begun to coalesce around a powerful new way of looking at added sugar: as perhaps the number one most significant health threat in America. But what exactly is “added sugar,” and why do experts suddenly believe that it’s the ISIS of nutrition?

When they talk about “added sugar,” health experts aren’t talking about the stuff that we consume from eating whole foods. “Added sugars are sugars that are contributed during the processing or preparation of foods and beverages,” says Rachel K. Johnson, PhD, RD, professor of nutrition at The University of Vermont. So lactose, the sugar naturally found in milk and dairy products, and naturally occurring fructose, the sugar that appears in fruit, don’t count. But ingredients that are used in foods to provide added sweetness and calories, from the much-maligned high fructose corn syrup to healthier-sounding ones like agave, date syrup, cane sugar, and honey, are all considered added sugars.

That’s because naturally occurring sugars, like what you find in an apple, come with their own health posse—fiber, which slows the digestion of the sugar and prevents it from spiking insulin response and damaging your liver, two serious side effects of added sugar. “It’s almost impossible to over consume fructose by eating too much fruit,” says Johnson. Consider this: You’d need to eat six cups of strawberries to get the same amount of fructose as in one can of Coke.

Fortunately, giving up added sugar has been shown to have several dramatic and rapid impacts on your health. In a newly released study, children who cut added sugars from their diets for just 9 days showed dramatic improvements in cholesterol and blood sugar levels.

On the flip side, adding sugar to your diet can quickly put your health into a spiral: People who consumed beverages containing high fructose corn syrup for two weeks significantly increased their levels of triglycerides and LDL cholesterol (the “bad” cholesterols), plus two proteins associated with elevated cholesterols and another compound, uric acid, that’s associated with diabetes and gout. So found a 2015 study in the American Journal of Clinical Nutrition.

In fact, in a 2014 editorial in the journal JAMA Internal Medicine, the authors made a bold statement: “Too much sugar does not just make us fat; it can also make us sick.”

The editors of Eat This, Not That! took a look at the most recent research and discovered just how much harm added sugars are doing to us:

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