Not-so-healthy ingredients are hiding in your otherwise healthy food.

A new study, published in the Journal of the American Dietetic Association, looked at how much consumers actually pay attention to Nutrition Facts labels on food products.

When the study participants were asked about their label-reading habits, many said they read the nutrition facts: for example, 33 percent reported "almost always" reading the calorie content. (The number of people who reported reading other components of the label, such as fat and sugar content, was lower.) But when the researchers put the study participants to the test with an eye-tracking device, those who truly read the Nutrition Facts label was much lower (only 9% looked at calorie counts, for example)-and even when consumers did examine the nutrition information, very few assessed every component of the label.

As a dietitian and nutrition editor of EatingWell Magazine, I'm not terribly surprised by these findings. Nutrition Facts panels can be tedious to read-and, frankly, they aren't nearly as visually appealing as the rest of the food package and the claims on it. Which is why, unless you're a dedicated, detailed label-reader, you might be surprised to learn that sometimes there are not-so-healthy ingredients hiding in food you'd otherwise think is healthy.

Here are four food categories that, surprisingly, contain not-so-healthy ingredients that you should watch out for:

-Brierley Wright, M.S., R.D., Nutrition Editor, EatingWell Magazine

Trans Fats in Margarine and Buttery Spreads

Trans Fats in Margarine and Buttery Spreads

Choosing a butter substitute can help you cut calories, but it's not necessarily a heart-healthier choice. When it comes to margarine and buttery spreads, you'll find all sorts of oil-based spreads in this category. "Margarine" is a product that has 80 percent fat, like butter, but because it's made from vegetable oils, it delivers more "good" fats than butter. Many (but not all) other "soft spreads" or "tub" buttery products have less total fat as well as less saturated fat and/or fewer calories. But not all products are created equal: some contain trans fat, which, like saturated fat, raises your "bad" LDL cholesterol, but possibly even more than saturated fat does, according to research. Trans fat also lowers your "good" HDL cholesterol. Be sure to scan the ingredient list for the words "hydrogenated" or "partially hydrogenated." If the ingredient list includes one of these, then the product is not really trans-fat-free. (The FDA allows manufacturers to round down on the label: when a food has less than 0.5 gram trans fat per serving it can be rounded down to 0 and labeled as trans-fat free.)

Pictured Recipe: Gorp

Added Sugars in Dried Fruit

Dried fruit is a great snack-delivering fiber and important vitamins and minerals, plus it's easily packable and doesn't need to be refrigerated. Even better, 1/2 cup of dried fruit counts as one of your daily servings of fruit! But there's a catch: dried fruit can also deliver unnecessary added sugars (an ingredient that we already overconsume)-and those added sugars can sometimes add an extra 50 calories to 1/2 cup of dried fruit. It's difficult to know how much added sugar is in most processed foods because food manufacturers aren't required to disclose the amount of natural versus added sugars in their products on the Nutrition Facts panel-when "sugars" are listed, the total number includes both naturally occurring and added sugars. To find out if there's added sugar in your foods, look at the ingredient list for sugar and all its aliases: corn sweetener or syrup, high-fructose corn syrup, fruit juice concentrates, invert sugar, malt sugar, syrup and sugar molecules ending in "ose" (dextrose, fructose, glucose, lactose, maltose, sucrose).

Trans Fat

Oils in Packaged Foods

Packaged convenience foods that you would assume are healthy, such as commercial salad dressings, crackers, breads, granola bars, etc., often contain palm oil and soybean oils-as well as corn, cottonseed, safflower and sunflower oils-all of which are rich in omega-6 oils. Why does that matter? Omega-6 fats compete in your body with healthy omega-3 fats, which benefit your heart and may also keep you happy. So look for products that don't include these oils-or at least contain "high oleic" versions of oils that are rich in omega-6 fats. (These high-oleic oils are produced using plants that have been bred or engineered to have more monounsaturated fats and fewer omega-6 fats.)

Artificial Sweeteners

Artificial Sweeteners in "Lower-Sugar" And "Sugar-Free" Products

Most of us eat too much sugar. On average, Americans consume 475 calories of added sugars every day (that's 30 teaspoons), which is three or four times what's recommended by the American Heart Association. And according to a new report from the Centers for Disease Control, 16 percent of kids and adolescents' total daily calories comes from added sugars! To cut back on added sugars, food products labeled "lower sugar" or "sugar-free" may seem like a healthier alternative. But you might be surprised to know that some of these food products-like some lower-sugar instant oatmeals and sugar-free jams and jellies-may be made with artificial sweeteners. If you want to limit your artificial-sweetener consumption, check the ingredient list for these terms: sucralose, aspartame, saccharin and stevia.