Your body depends on fat for protection, warmth and to help carry out essential functions. Dietary fats, however, can affect cholesterol. According to New York University's Langone Medical Center, unsaturated fats help reduce low-density lipoprotein: bad cholesterol, which increase the risk for heart disease and stroke, and increase high-density lipoprotein: good cholesterol, which decreases the risk of coronary heart disease. Include in your diet foods that contain unsaturated fats, such as olive oil, avocados, nuts and seeds. Fish like salmon and trout are rich in polyunsaturated fats and heart-healthy omega-3 fatty acids. Because saturated and trans fats raise bad cholesterol and lower good cholesterol, limit your intake of animal products, such as red meat, and whole-fat dairy and avoid deep-fried foods.