CHICAGO (CBS) – It’s no secret many foods contain sugar, but you might be shocked to learn just how much is in some seemingly healthy options. CBS 2′s Dorothy Tucker put people to the test to see if they could convert grams on food labels to teaspoons, and asked one consumer advocate about his simple solution.

Michael Roe thought the 72 grams of sugar in a can of AriZona Iced Tea amounts to about 6 teaspoons. He was wrong.

The 72 grams of sugar in that drink are equal to 17 teaspoons of sugar, the same amount you’d get form six Twix bars.

A survey of 700 readers by Consumer World found 80 percent of people were confused about the nutritional information on food labels, because all food labels use the metric system, and ingredients like sugar are measured in grams, not teaspoons.

Others were surprised to learn a bottle of Nantucket Nectars Orange Mango drink lists 65 grams of sugar per bottle, the equivalent of 15 teaspoons of sugar.

The 57 grams of sugar in a Minute Maid Cranberry Apple Raspberry juice bottle equals 13½ teaspoons.

Even a McDonald’s Quarter Pounder with Cheese has a shocking 10 grams of sugar, or 2⅓ teaspoons.

“This is an enormous amount of sugar,” said Achieng Obung.

Holly Herrington, a registered dietician at Northwestern University, said, “Sugar itself is not bad. The problem is that we consume way too much sugar.”

Herrington said consumers aren’t used to measuring ingredients in grams.

“If I’m using spoons, I’m not measuring my grams at home,” said Herrington.

Even seemingly healthy foods like Nature Valley Granola bars have 11 grams of sugar in two bars. That’s more than 2½ teaspoons.

A Dannon Yogurt cup has 25 grams of sugar. That’s six teaspoons in a 6-ounce container.

“That’s a lot of sugar,” said Salma Saad.

Consumer World’s Edgar Dworsky calls the labels confusing and wants the FDA to include teaspoons on labels, so they are easier to understand.

Dworsky said he believes manufacturers love that confusion “because consumers are in the dark about how much sugar…is really in the things they normally eat.”

The FDA has not yet responded to Dworsky’s suggestion to include teaspoons on the labels. They also haven’t responded to CBS 2’s requests for comment.

According to dieticians, women should not have more than 24 grams of sugar a day, or about 6 teaspoons. For men it’s about 36 grams, or 9 teaspoons.

The companies cited in this story are doing what they’re legally required to do, listing sugar in grams on their nutrition labels.