Olive oil, like other oils, contains nine calories per gram. In this regard, all oils are created equal.
But we all know that olive oil is not just another oil. The European Union recognized that consumption of oleic acid, vitamin E and polyphenols contained in olive oils have health benefits (Regulation 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods, other than those referring to the reduction of disease risk and to children’s development and health). Moreover, and as regards the polyphenols (which "contribute to the protection of blood lipids from oxidative stress"), the regulation establishes a recommended daily intake of 20 grams of virgin olive oils which contain at least 5 milligrams of hydroxytyrosol (a compound with antioxidant properties) contained in that same proportion of oil.
Some will think, then, that the greater the intake, the greater the health benefits, but science tells us this is only a half-truth. An oil-free diet is just as inadvisable as a diet rich in oil.
So what's the right amount?
Like everything in life, the issue is balance. It's important to eat olive oil, but never in excess. How much is just enough? Science can help us out on this one— specifically, the researchers in the PREDIMED Study (Effects of the Mediterranean diet on the primary prevention of cardiovascular diseases). For years, thousands of participants in the study ate a controlled Mediterranean diet supplemented with extra virgin olive oils, "advised to eat 50 milliliters per day, i.e. around 5 tablespoons of extra virgin olive oil. Over time we discovered that they were consuming around 40 milliliters per day (roughly 37 grams)", says Ramón Estruch, who coordinates the study.
In time, PREDIMED researchers confirmed that those people have lower blood pressure and are less likely to suffer from diabetes, depression and heart disease.
The study also confirmed other evidence: "According to what we've seen to date, people who ate a Mediterranean diet with extra virgin olive oil did not gain weight, despite a higher calorie intake than the control group (on a low-fat diet). In contrast, we have verified that there is a tendency to lose weight and waist circumference. Consequently, there's no concern about including olive oil in our diet just because it's a fat."