Eating a diet rich in monounsaturated fat reverses insulin resistance compared to diets rich in carbohydrates or saturated fat.  Monounsaturated fat also increases HDL cholesterol and lowers triglycerides compared to high carbohydrate diets.

The so-called Mediterranean diet, generally regarded as protective against heart disease, involves replacing some carbohydrates with monounsaturated fats.  Monounsaturated fats are not as susceptible to oxidation as polyunsaturated fats (Omega-3 and Omega-6), so you can use them for light cooking.

Olive oil, nuts and avocados are excellent sources of monounsaturated fat.

PMID: 17914131