How to Spot Sneaky Fat: The Truth About Hidden Trans Fats
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How to Spot Sneaky Fat: The Truth About Hidden Trans Fats

Trans fats are the new dietary demon and are twice as bad as any other fat. To protect yourself, you need to do a lot more than just read the new food labels.

Coming Clean About Trans Fats

Full disclosure: I am a baked-goods junkie. This is not something a health writer should admit. But it's my only vice. I am slim. I exercise regularly. And my eating habits are pretty healthy overall. I never have fast food, order fries maybe three times a year, remove the skin from my chicken, eat only lean red meat, drink skim milk, and make most of my meals from scratch using fresh ingredients. But every afternoon, the sweets craving hits. I may have a few cookies or buy a cupcake at the bakery. Occasionally I lust after a brownie. Once a month I bake a pie.

So when my doctor called me recently to tell me that my cholesterol was still 211 (despite having banned cheese and butter from my kitchen and upping my exercise to reduce it from 225), I was shocked. "I'm practically a vegetarian!" I insisted. After I hung up the phone, I wondered what was wrong. Now I may have the answer: trans fatty acids.

Trans fats have been present in our nation's food supply since early in the 20th century, lurking in many of the foods I love (packaged cookies, brownies, and piecrust, some bakery pastries) and many of those I avoid (fast-food fries, chips, prepared foods, doughnuts).

Trans fats occur naturally in low levels in foods such as milk, beef, and lamb, but the big problem comes from all the manufactured fats we eat: They're what keep foods from turning rancid on grocery store shelves and give croissants their flakiness. They keep muffins moist, make fries and chips finger-licking good, and satisfy my sweet tooth.

Though trans fatty acids account for only 5 to 10 percent of the fat in our diet, that's enough to wreak havoc on our cholesterol, clog our arteries, and take a staggering toll on our hearts. "Trans fat is, gram for gram, twice as bad for your cholesterol score as saturated fat," says Meir J. Stampfer, MD, professor of epidemiology and nutrition at the Harvard School of Public Health and a senior investigator for the Nurses' Health Study, an ongoing look at health issues confronting nearly 240,000 female nurses.

According to researchers, trans fats are to blame for anywhere from 70,000 to 288,000 heart attacks (fatal and nonfatal) in Americans each year. That's why as of this past January, the FDA requires all food manufacturers to list the trans-fat content of their products on food labels directly under the amount of saturated fat. (Some manufacturers started doing this voluntarily before the January 1 deadline.)

"Eating foods that contain trans fatty acids is like riding in a car without using a seat belt," says Michael F. Jacobson, PhD, executive director of the Center for Science in the Public Interest (CSPI), a Washington, D.C.-based consumer advocacy organization concerned with health and nutrition issues. But here's the rub: While we know what a healthy level of saturated fat is (10 percent or less of your daily calories), no one knows what a healthy level would be for trans fatty acids. And worse, you can't always trust the new food labels. But there are ways to find the hidden fat even the label doesn't reveal.

What Is Trans Fat?

To understand what a trans fat is, you first need a short primer on fats. Fats come in solid or liquid form and are a combination of saturated fat -- which is bad for your heart -- and unsaturated fat, which is not. Some fats are higher in saturated fat and others have more of the unsaturated variety.

Saturated fat, which raises cholesterol, is found in animal products -- think butter, whole milk, and steak -- and in tropical oils such as palm and coconut. Unsaturated fats, which can lower LDL (bad) cholesterol, are always liquid and found in vegetable oils. They come in two forms: monounsaturated (olive and canola oils) and polyunsaturated (safflower, sunflower, corn, and soybean oils). All fats are calorie dense, so eat even good ones in moderation.

Unlike the natural trans fats found in milk and some meats, man-made trans fatty acids are by-products of heating polyunsaturated liquid vegetable oil in the presence of hydrogen, which is done to create a fat that remains solid at room temperature and that won't go bad as quickly -- useful traits for cooking. The resulting partially hydrogenated fat is the artery clogger. (In a similar process, polyunsaturated oil can be fully hydrogenated, which makes it even more solid. This form doesn't have quite as harmful an effect on cholesterol levels, but is less useful for cooking.)

Trans fats were developed because they're cheaper to produce in mass quantities than animal fats, such as butter, and they can be reheated over and over again without breaking down. In the '60s, when heart-disease concerns were raised about saturated fats, some research claimed that margarine -- which is made from trans fats -- was healthier than butter, and food makers began to use trans fats widely. But since the '90s, evidence has been accumulating that trans fats may be even worse for the heart than butter.

We all know the dangers of saturated fat. It raises your LDL cholesterol, causing a buildup of plaque in your arteries, which in turn can cause heart disease. But at least saturated fat leaves your HDL alone, or slightly raises it (though you shouldn't turn to it to bump up your good cholesterol).

Trans fats, however, deliver a damaging one-two punch: They not only raise your LDL, they also lower your HDL. In one study, researchers found that replacing a diet high in heart-healthy monounsaturated fats (such as olive or canola oil) with a diet high in trans fatty acids increased LDL cholesterol by 14 milligrams per deciliter of blood and decreased HDL by 7 mg per deciliter. While replacing monounsaturated fat with saturated fat (such as butter) caused a similar rise in LDL, it had no effect on HDL. Trans fats also boost blood levels of C-reactive protein (CRP), a marker for inflammation that has been associated with heart disease, according to a study published in the Journal of Nutrition.

In fact, trans fats are so bad for the heart, says Dr. Stampfer, that if you replaced just 2 percent of the calories in your diet that now come from carbohydrates with trans fat, your risk for heart disease would skyrocket by 93 percent.

Hidden Dangers

No one knows how much trans fat a typical American eats -- estimates range from 2.6 grams to 12.8 grams per day, according to the American Heart Association -- or how much constitutes a safe amount. In adjusting our diets, how low should we go? The Institute of Medicine of the National Academy of Sciences recommends that levels be kept as low as possible, as does the government's Dietary Guidelines for Americans.

The new labels help, but not completely. The FDA is now permitting any food that contains less than 0.5 gram of trans fat to carry a label that proclaims 0 grams of trans fats or "not a significant source of trans fat." (Canada, on the other hand, draws the line at 0.2 gram.) "Some people will still get a significant amount of trans fat if there is 0.3 gram in one food and 0.2 gram in another," says Dr. Jacobson, whose organization has been leading the charge against trans fats in the food supply.

And, of course, food labels help you keep tabs on the trans-fat content of foods you buy at the grocery store only. There's no way to tell how much trans fat is in the carton of fries you devour at your favorite fast-food place, in the meal you order at a restaurant, or in the cupcake you buy at the corner bakery. Restaurants and bakeries don't have nutrition-labeling requirements.

Avoid the Sneaky Fat

In response to health concerns about trans fats, many food manufacturers have reformulated some or all of their products to reduce, or eliminate, trans fats. "People now have the option of choosing products made without partially hydrogenated fat," says Alice Lichtenstein, DSc, professor of nutrition science and policy at the Friedman School of Nutrition Science at Tufts University, in Boston.

For example, in anticipation of the labeling change, Frito-Lay began listing the trans-fat content of its foods on labels in 2003. It also began eliminating trans fats from most of its products, including Cheetos, Doritos, and Lays chips, by cooking them in corn and sunflower oils rather than hydrogenated oil. Kraft Foods has replaced many of its products, including Triscuits and Oreos, with trans fat-free versions. In December 2005, Kellogg announced it would reduce trans fats in some of its products, such as Cheez-It crackers and Pop-Tarts, by using a new soybean oil that reduces the need for hydrogenation.

How much will you miss the taste of trans fats? Ladies' Home Journal staffers did a blind taste test of the original Oreo and the new zero-trans-fat variety to see whether they could taste a difference. The verdict? A three-way split: Some preferred the new cookie; others, the original; the rest liked both equally.

Whether you decide to banish trans fatty acids from your kitchen or eat as few as possible, you still need to scrutinize a packaged food's ingredients listing. One sign a food is not trans fat free: You'll see "partially hydrogenated oil" on the list.

If you balk at reading labels each time you shop, Dr. Lichtenstein suggests visiting the Web sites of food manufacturers whose products you buy regularly. Read up on each food's nutrition information and create a shopping list of foods that are low in trans fats or trans fat free.

To make sure you don't overdo trans and saturated fats, add up the total amount of both fats listed on the food label, advises Katherine Tallmadge, RD, national spokeswoman for the American Dietetic Association and author of Diet Simple. Then follow the heart-healthy guidelines established for saturated fat: If your LDL is lower than 130, don't exceed 10 percent of daily calories -- or 22 grams -- from saturated fats, based on a 2,000-calorie-a-day diet. If your LDL is above 130, don't get more than 7 percent of calories -- or 15 grams per day -- from saturated fats. No more than 1 percent of daily calories should come from trans fats -- if that!

Navigating your way through a restaurant menu or bakery will be trickier. Some restaurants, such as Legal Sea Foods, no longer use partially hydrogenated oil. In August 2005, the New York City Department of Health and Mental Hygiene asked city restaurateurs and food suppliers to voluntarily eliminate partially hydrogenated oils from their kitchens. And the Tiburon, California-based group BanTransFats actually got all 18 restaurants there to agree to a ban, making Tiburon America's first "Trans Fat-Free City." (For the latest news on trans fats, go to or, a project of CSPI.)

But many restaurants have not embraced the trans fat-free movement. You can question the waitstaff about the oil a food is cooked in, but they may not know. Sometimes even chefs don't know: A restaurant that refrains from frying in partially hydrogenated oil may still serve foods precooked in it by a food distributor.

As vital as it is to minimize trans fats, it's best not to fixate on them the way some people did on, say, low-fat cookies or low-carb foods. "No one food is ever going to make much of a difference on its own," says Marion Nestle, PhD, MPH, professor of nutrition, food studies, and public health at New York University, in New York City, and author of What to Eat: An Aisle-by-Aisle Guide to Savvy Food Choices and Good Eating. "Rather it's the totality of what people eat that counts."

Dr. Nestle calls trans fats "calorie distractors," and on this matter she's not alone. Overeating is at the root of our nation's obesity crisis, and many experts worry that focusing on trans fats will shift attention away from the need for a balanced, nutritious diet and portion control. "The biggest health challenge for most Americans is eating fewer calories," says Dr. Lichtenstein. An occasional slice of pie, even with trans fats, won't kill you. Just don't have one too often.

The Trans-Fat Trap

It's easy to rack up an unhealthy intake of trans fat. Take this 1,800-calorie diet. Just a few modest indulgences give you almost 5 percent of calories from trans fat.


No Trans Fat:

  • 8 oz. orange juice with calcium
  • Coffee with 1 tbsp. half-and half

Trans Fats:

  • 1 doughnut (3.19 grams)


No Trans Fat:

  • Ham on 2 slices rye bread
  • 1 slice nonfat American cheese
  • 1 tbsp. ketchup
  • 1 bottle water

Trans Fats:

  • 1 small fast-food French fries (3.43 grams)


No Trans Fat:

  • 1 8-oz. glass skim milk

Trans Fats:

  • 2 cookies (1.72 grams)


No Trans Fat:

  • Spaghetti (1 cup)
  • 1/2 cup chunky vegetable-style tomato sauce
  • 1 small green salad with 2 slices tomato, 2 slices cucumber
  • 1 tbsp. vinaigrette
  • 1 piece Italian bread
  • 1 glass (3 1/2 oz.) white wine
  • 1 cup fresh strawberries

Trans Fats:

  • 2 tsp. stick margarine (1.24 grams)

TOTAL TRANS FAT: 9.58 grams

Source of trans fat counts: Adapted from the Harvard School of Public Health

What the Food Label Doesn't Tell You

If a label says zero trans fats, don't take that literally -- or lightly. FDA rules let a manufacturer market a food as having no trans fats if it contains less than half a gram per serving. To find the truth read the ingredients list.

If it includes "partially hydrogenated vegetable oil," the food has a small amount of trans fat even if the label says zero. The higher up on the list the mention occurs, the more trans fat it has. (Remember, too, that "one serving" can be very small; the amount you actually eat will likely rack up even more fat.)

Sometime the ingredients label hides trans fats by using words that mask the truth. Here's how to find them anyway:

If the label mentions...

  • Partially hydrogenated oil, it has trans fats
  • Fully hydrogenated oil, it does not have trans fats
  • Shortening, it likely has trans fats (may contain partially hydrogenated oil)
  • Hydrogenated oil, it possibly has trans fats (it could be the partially hydrogenated type)

Is Butter Now Better?

Now that trans fats have been demonized, is it okay to switch back to butter or even lard when you cook or bake at home? Sadly, no. Both are high in artery-clogging saturated fat. Instead, use a monounsaturated oil, such as olive or canola oil, recommends Katherine Tallmadge, RD, national spokeswoman for the American Dietetic Association. For best results, you may need a recipe that calls for oil: Tallmadge includes a few in her book Diet Simple. Another good source of recipes: The Trans Fat Free Kitchen, by Ronni Julien, MS, RD. We also like The Sonoma Diet's Apple-Blueberry Tarts, a recipe with a canola-oil crust. There's also a trans fat-free vegetable shortening you can try for piecrust and other baked goods.

If you can't imagine Grandma's chocolate-chip cookies without butter or a family birthday party without the mocha cake from the neighborhood bakery, indulge. An occasional treat won't do in your health or your daily diet. Here's how some common shortenings and spreads stack up.

Butter: Derived from milk fat. High in saturated fat and cholesterol, but has zero trans fats. One tablespoon of extra-creamy unsalted stick butter has about 110 calories, 12 grams of total fat, and 8 grams of saturated fat. One tablespoon of regular unsalted stick butter has about 100 calories, 11 grams of total fat, and 8 grams of saturated fat. One tablespoon of whipped unsalted butter has roughly 50 calories, 6 grams of total fat, and 3.5 grams of saturated fat.

Margarine: Made from vegetable fat; no dietary cholesterol. Stick margarine is high in trans fats, but the softer a margarine is, the fewer trans fats it contains. Case in point: Stick margarine has about 100 calories per tablespoon, 11 grams total fat, and 5 grams of saturated and trans fat. One tablespoon of light margarine spread has around 40 calories and zero grams of saturated or trans fat.

Vegetable Shortening: Usually made from partially hydrogenated soybean and cottonseed oil. You can find zero trans fat versions of vegetable-oil shortening made from fully hydrogenated cottonseed oil. Both have the same calorie (110 per tablespoon) and total fat (12 grams) counts.

Lard: Melted, rendered pork fat (think of the fat that remains in the frying pan after you cook bacon). It's high in calories, artery-clogging fat, and cholesterol. One tablespoon of pure lard has 115 calories, 12.8 grams of total fat, and 5 grams of saturated fat.

Originally published in Ladies' Home Journal magazine, April 2006.