The researchers randomly assigned study patients to 1 of 2 diets that had identical amounts of total fat, saturated fat, carbohydrate, and cholesterol. However, the first low-fat diet included a number of reduced-fat prepared foods, such as low-fat cheeses, low-fat frozen lasagna, and high-sugar snack foods. The second diet included high amounts of vegetables, fruits, legumes, whole grains, and fruits. Before and after 4 weeks of the study diets, researchers measured levels of total cholesterol, LDL cholesterol (“bad” cholesterol), high-density lipoprotein (HDL) cholesterol (“good” cholesterol), and triglycerides. (Triglycerides are another type of fat in the blood that has been linked to heart disease.)