Cake mixes and frostings

Even if you find a cake or muffin mix that's trans fat-free, you could still see the telltale word "shortening" on many ingredients lists, which means there are trace amounts.

Plus, you still need to worry about how you're going to top your creation. Duncan Hines's frostings contain 1.5 grams per serving, while Betty Crocker's contain up to 2 grams. (Betty Crocker's homestyle fluffy white frosting mix, however, is trans fat-free.)

Pancakes and waffles

Pancake and waffle mixes, too, often contain hydrogenated oils.

Bisquick's original pancake mix still contains 1.5 grams trans fat per serving, so opt for the newer (and trans-fat free) Bisquick Complete, Gluten Free, or Heart Smart formulas.

Fried chicken

Although you are less likely to find trans fat in frozen fried chicken, including Banquet and Walmart brands, there are still some offenders out there: Kid Cuisine All American Fried Chicken meal— — a children's product — —has 1 gram of trans fat.

Dining out at a restaurant? The same rules that apply to french fries apply to fried chicken (and fried fish, for that matter), says Giancoli. Unless you know an establishment does not fry in hydrogenated oils, assume that it does — —or ask for clarification.

Ice cream

Certain flavors of Haagen-Dazs ice cream — —including pineapple-coconut, cherry-vanilla, caramel cone, green tea, and even plain old vanilla— — contain 0.5 grams of trans fat per serving. But if you read the ingredients list, the telltale listing of partially hydrogenated oils is missing.

That is probably because there are naturally occurring trans fats in fat-containing dairy products, says Giancoli. However, it is not clear if these naturally occurring trans fats are as bad for you as the trans fats in processed food. They're high in calories, however, so you should still watch your intake.

Nondairy creamers

For coffee lovers, nondairy creamers can become an integral part of your morning. Over time, however, they can also add a considerable amount of trans fat to your diet. Take Coffee-Mate products, for example: Each serving contains 0 grams trans fat, yet, for most flavors (even the fat-free and low-fat varieties), partially hydrogenated oils are the second or third ingredient listed.

"At breakfast when you're making coffee, you're not usually thinking about nutrition or reading labels," says Giancoli. "The amounts can really sneak up on you if you drink a lot of coffee."

Microwave popcorn

Popcorn in itself is a healthy snack, and a serving of whole grains to boot. But when you pour on the gooey toppings, there's no telling what you're really adding.

Case in point: Orville Redenbacher's microwave popcorn. The Pour Over Movie Theater butter flavor contains 0.5 grams of trans fat per serving, and the Pour Over Caramel flavor contains 1.5 grams.

Pop Secret is even worse: The butter and extra-butter flavors each contain 5 grams of trans fat per serving— — about 15 grams per bag!

Ground beef

Just as with dairy products, beef can also contain natural trans fat. So although the big chains have worked hard to remove hydrogenated oils from their fried foods, most restaurant burgers still contain significant levels of trans fat.

You'll also find trans fat in many frozen burgers, beef sausages, beef hot dogs, and ground beef.

"Most of us should be reducing our consumption of animal products anyway, so it's a good idea to limit these products and choose plant-based foods instead," says Giancoli.

Cookies

Oreos phased out trans fat in 2006 after Kraft Foods was sued by the Campaign to Ban Partially Hydrogenated Oils. (The lawsuit was dismissed.) Chips Ahoy!, Nilla Wafers, and Girl Scout cookies also now fall below 0.5 grams per serving, although some still contain partially hydrogenated oils.

Check other store-bought cookies and cookie dough: Carr's ginger-lemon creme cookies contain 2 grams of trans fat per serving and Pillsbury's Ready To Bake cookies contain up to 2.5 grams of trans fat per serving. "Anything that can sit on a shelf or in a package for a while needs to be stabilized, which often means it's hydrogenated," Giancoli says.

Biscuits and sweet rolls

Many chains — —Burger King, McDonald's, and Popeyes— — now offer biscuits with 0 grams of trans fat per serving. Although most Cinnabon locations are trans fat–free (including all locations in California and New York), it still creeps into the products at some. Krispy Kreme's large cinnamon and pecan rolls still have 1 gram each.

And check the grocery-store type. Pillsbury's refrigerated Grands! Homestyle Butter Tastin' and Grands! Homestyle Buttermilk contain 3 grams each. The brand's caramel and Cinnabon cinnamon rolls with icing contain 1 and 2 grams of trans fat per serving, respectively, and many of the varieties that list 0 grams still contain hydrogenated oil.

Breakfast sandwiches

Doughnuts are often the poster-child food for trans fat, but in 2007, Dunkin' Donuts reformulated their menu so most items now contain 0 grams per serving (or at least fall below 0.5 grams).

Unfortunately that's not always true for breakfast sandwiches served on biscuits, such as Burger King's, some of which contain 1 gram of trans fat. And at the grocery store, steer clear of Jimmy Dean packaged sandwiches, which have up to 3 grams of trans fat each.