Fat is the not same thing as cholesterol. These modified fats are called trans fatty acids and can elevate your blood cholesterol level. All fats contain the same amount of calories. Margarine is always better for you than butter. Not always true.
Many margarines contain trans-fatty acids.
Choose soft tub margarine over stick to avoid the trans fats. Read the labels and avoid products that contain partially hydrogenated shortenings. Vegetarian diets are naturally low in fat. Some vegetarian diets replace meat with cheese and eggs as a primary protein source and can contain a lot of fat, especially saturated fat. Eating less cholesterol is the best way to lower your cholesterol.