Olive oil has some health advantages over butter, but that doesn't mean you can dip crusty Italian bread into it without restraint.
Because oil is a liquid, the bread tends to soak up more olive oil than the amount of butter you'd normally spread on the same slice of bread, researchers have found. The labs for their experiment were two Italian restaurants, where they used hidden cameras.
Over the course of several evenings, 341 diners were served Italian bread with either a small dish of olive oil or the same amount of butter. After the diners left the restaurants, the remaining oil, butter and bread were weighed.
People consumed about 26% more olive oil than butter per slice of bread. This resulted in 44 calories of fat per slice of bread with olive oil, compared with 33 calories of fat for bread and butter. The good news here is that the penalty wasn't as great as it might seem -- the oil dippers actually consumed 230 fewer calories on average because they ate less bread.
So, on the calorie front, "If you can limit yourself to only one piece of bread, you're better off eating butter," says lead author Brian Wansink. But if you have a difficult time keeping your hand out of the bread basket, use oil, he suggests.
"Olive oil is a rich mouth experience, so we tire of it a lot faster than butter. Also, we tend to overeat familiar flavors, which is one reason why those who used butter ate three or more slices of bread compared to 2 1/2 slices for those who used olive oil," says Wansink, who is professor of nutritional science and consumer psychology at the University of Illinois at Urbana-Champaign.
Olive oil is a monounsaturated fat, which appears to lower the risk of clogged arteries and is more healthful for your heart and blood vessels than the saturated fat of butter.
The study was published in the July issue of the International Journal of Obesity.