Olives that are Greek kalamata olives are considered some of the best and healthiest olives in the world. A serving of about four kalamata olives provides around 1 gram of protein, 1 gram of fiber, 320 calories, and 8 grams of fat. Although they’re about 80% water, the fat they contain is ‘good’, a monounsaturated fat known as oleic acid that can help fight cholesterol, reduce inflammation and combat heart diseases.