Final answer:
Trans-fatty acids, commonly found in fast food, can increase the risk of heart disease by elevating LDL cholesterol levels and promoting plaque deposition in the arteries. Many fast food restaurants have eliminated trans fats from their menu items.
Step-by-step explanation:
Trans-fatty acids, commonly found in fast food, are a concern to nutritionists because they can increase the risk of heart disease. Trans fats are created through a process called hydrogenation, where unsaturated fats are chemically treated to produce partially hydrogenated fats, resulting in the formation of trans fats. These trans fats can elevate LDL ("bad") cholesterol levels and lead to plaque deposition in the arteries, which can ultimately result in heart disease. Many fast food restaurants have taken steps to eliminate trans fats from their menu items due to these health risks.