Trans Fats: The Science and the Risks

This man-made fat was developed to protect us against butter. Turns out, it acts like butter inside our bodies.

By Denise Mann
WebMD Weight Loss Clinic - Feature

Reviewed By Louise Chang, MD

What exactly are trans fats? How are they made? How bad are they, really? And just how solid is the science that the FDA consulted when they voted to list trans fats on nutrition labels? To get to the bottom of these and other questions about trans fats, WebMD spoke to leading nutritionists.

What Exactly Are Trans Fats?

Trans fatty acids or trans fats are formed when manufacturers turn liquid oils into solid fats. Think shortening and hard margarine. Manufacturers create trans fats via a process called hydrogenation. Hydro-what? In a nutshell, hydrogenation is a process by which vegetable oils are converted to solid fats simply by adding hydrogen atoms.

Why hydrogenate? Hydrogenation increases the shelf life and flavor stability of foods. Indeed, trans fats can be found in a laundry list of foods including vegetable shortening, margarine, crackers (even healthy sounding ones like Nabisco Wheat Thins), cereals, candies, baked goods, cookies, granola bars, chips, snack foods, salad dressings, fats, fried foods, and many other processed foods.