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What is Transfat?

Michael Pollick
Updated: Feb 21, 2024

If it were your job to create the world's unhealthiest food product, you might do well to duplicate trans fat, otherwise known as trans fatty acids. Trans fat's qualifications include increasing LDL (bad) cholesterol levels, reducing HDL (good) cholesterol levels, increasing arterial plaque production and causing general digestive disorders. There are also suggestions that trans fat reduces the absorption rate of essential vitamins and minerals. From a health standpoint, trans fat is often described as a heart attack in a box.

Food-based fats generally fall along three lines: saturated, unsaturated and trans fat. Broadly speaking, saturated fats are found in meats and other animal-based foodstuffs. Saturated fats are not especially healthy, but the body can tolerate modest amounts. Unsaturated fats occur naturally in vegetable-based oils and some seafood. Most unsaturated fats are considered very healthy, because they do not collect in the bloodstream and help reduce levels of LDL (bad) cholesterol found in saturated fats. The final category, trans fat, has become very controversial in recent years.

Trans fat shares many of the same characteristics as saturated fat, including the negative effect on cholesterol levels and the tendency to clog arteries. However, the base of many trans fat products is vegetable oils, which ordinarily provide healthy unsaturated fat. Trans fat is the result of an artificial process converting vegetable oil into a more stable form of shortening. Instead of using a saturated fat product such as butter, food companies often use trans fat products like Crisco or margarine.

Trans fat is created through a process called hydrogenation. Ordinary vegetable oils are placed in tanks with a reactive metal such as cobalt. Hydrogen gas is bubbled through the oil until the entire contents partially solidify. The resulting product is called partially-hydrogenated vegetable oil, since the hydrogenating process is stopped before the oil becomes completely saturated with hydrogen. There are some commercial examples of fully-hydrogenated vegetable oils, such as a form of Crisco shortening intended to replace the less healthy partially-hydrogenated variety.

The process for creating trans fat was created around the turn of the 20th century and has been a source of controversy ever since. The introduction of such consumer-friendly products as margarine and shortening were embraced by the public at first, since they replaced fats which often became rancid and unusable. Warnings against the prolonged use of margarine and other trans fat products were largely ignored or downplayed by the food industry. From a business standpoint, trans fat shortenings allowed convenience foods to be produced inexpensively, and with an increased shelf life.

Recent studies on the long-term effects of trans fat have led medical groups to speak out against the continued use of partially or fully-hydrogenated oils and shortenings. Beginning in 2006, commercial food producers must provide trans fat information on their nutritional labels, along with saturated and unsaturated fat contents.

WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Michael Pollick
By Michael Pollick
As a frequent contributor to WiseGeek, Michael Pollick uses his passion for research and writing to cover a wide range of topics. His curiosity drives him to study subjects in-depth, resulting in informative and engaging articles. Prior to becoming a professional writer, Michael honed his skills as an English tutor, poet, voice-over artist, and DJ.
Discussion Comments
By comfyshoes — On Feb 23, 2011

Suntan12 - I think that it is a good idea but I know that the restaurant industry would fight it because they would not want you to know how many calories and fat is laden in their meals.

Most people that go to a restaurant go to enjoy the food, but if they had this information restaurants know that many people would make different choices and they may exclude their restaurant from future consideration because the food is so fattening. This is why McDonald's offers its nutritional information on the bottom of a placemat when you would never notice it.

I know that everything in moderation is okay, but I feel so guilty eating something that I know is so bad for me that I would probably be one of those people that would not return to the restaurant if I knew how the foods were prepared.

I do feel better when I see that a food is transfat free, but I always double check the ingredients because much of the processed foods do still use traces of transfat.

By suntan12 — On Feb 20, 2011

Mutsy - You know in New York City all of the restaurants are required to list all of the nutritional contents of any meal that they serve. It is amazing how many calories and how much fat is in some of the entrees.

Having all of that nutritional information in front of you does influence your decision on what to order. I went to a Friday’s restaurant and the healthiest thing to order was a cobb salad that had over 900 calories. Most of the entrees were well over 1,300 calories.

I can see if you eat out a lot how you can easily gain weight because these foods have so many calories and their portion sizes are about three times the average serving size.

If you factor the amount of fat in these foods you will be really in for a shocker. It does feel strange to see the caloric content of the foods up front like that but I think that it would be a good thing.

By mutsy — On Feb 20, 2011

Icecream17 - I have tried those Wendy’s French fries and they are really good. I am glad that more attention is being placed on the use of transfat, but we really need to pay attention to all of the food labels because a product may not register any transfat when you look at the caloric section of the label but it will contained hydrogenated oil in its ingredients which is considered transfat.

So this can be tricky because there are so many foods that contain transfat you would not believe it. Looking at the label will help us determine if the food is right for you.

Sometimes companies will add more sugar or salt in order to enhance the flavor when they remove the transfat so we really cannot take the companies at their word we have to check the label ourselves and make sure we know what we are eating.

By icecream17 — On Feb 18, 2011

Obsessedwithloppy - That is great to hear. I know that a lot of states now have bans on transfat food. As a result a lot of fast food restaurants have removed most of the transfat from their products.

For example, Wendy’s and McDonald’s have removed the transfat from their French fries which used to contain almost five grams of transfat per serving.

There was some controversy when McDonald’s altered its formula of its French fries but they are still delicious. I have also tried the new Wendy’s French fries with sea salt and they taste terrific and they are also transfat free. They still do contain fat so you have to eat these fries in moderation.

I also wanted to add that the Mc Donald's burgers do contain a small amount of transfat and I think that is due to the processed cheese that they use. The hamburger has no transfat which is why I mention it.

By obsessedwithloopy — On Jul 26, 2008

A new law was signed in California that will ban trans fats from restaurant food and baked goods. California is leading the way that will most likely be followed by the rest of the country.

Michael Pollick
Michael Pollick
As a frequent contributor to WiseGeek, Michael Pollick uses his passion for research and writing to cover a wide range...
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