There is so much misinformation in regards to the use of fats and oils and their health benefits. This study proves those who consume extra Virgin olive oil have lower sugar and cholesterol levels.
So what oil should you use in cooking? The best oil is light olive oil. It has a higher heating temperature (takes longer to convert into nasties) and doesn't have any strong taste. Extra Virgin olive oil is best used for salad dressings and is best not to cook with.
Overall, olive is a great source of polyunsaturated fatty acids and is part of the reason why the traditional Mediterranean diet is still considered the healthiest!
Here is a great article for some extra reading: