 Recently, researchers in Spain wondered what would happen if they replaced much of the refined olive oil in people's diets with extra virgin olive oil, or walnuts, or almonds. What were the effects on people's cardiovascular risk factors after a month on each of the different diets? Same people, but three different months diets different only by the main source of fat, and this is what they found. The people in the nut groups did significantly better, dropping their total cholesterol about 7%, knocking about 20 points off their bad cholesterol. However, the extra virgin olive oil did do somewhat better than the refined olive oil, presumably because it retains a few more phytosterols, but nuts and seeds remain the best source of fat. Whole food sources of fats, like everything else, tend to be preferable. One can think of extra virgin olive oil like fruit juice. It's got nutrients, but the calories you get are relatively empty compared to the whole fruit. Olives are, after all, fruits. You fresh squeeze them and you get olive juice, less nutrition than the whole fruit, but then it gets even worse. They throw away what's called the olive waste water, which contains all the water-soluble nutrients in olive. So the oil just has a small fraction of the nutrition of the whole fruit. So why not just eat the olives? Well, the problem is that they're soaked in brine, such that a dozen olives could take up half your sodium intake for the day. So I suggest eating them only in moderation.