What it is: A diet that emphasizes high consumptions of oil, fruits, vegetables, legumes, nuts, and fish; moderate quantities of dairy; and a low amount of meat. Why it works: The Mediterranean diet’s most compelling component is its emphasis on antioxidants, which clean up after the toxic byproducts of burning calories, preventing them from causing cell damage. Olive oil is also lauded for providing a wealth of nutrients, including a high level of monosaturated fats that may reduce risk of coronary heart disease and regulate cholesterol. What the experts say: “Both men and women who report eating foods closest to the [Mediterranean diet] are about 10-20 percent less likely to die over the course of a study of heart disease, cancer or any other cause,” according to medical researchers in the October 2009 issue of Maturitas. Heavy amounts of vegetables and olive oil may also enhance bone metabolism, prevent cancer, rheumatoid arthritis, and age-related diseases like Alzheimer's and Parkinson's diseases.