Cardiovascular disease (CVD) is the leading cause of death in women. Premenopausal women have a lower risk of CVD compared with men of a similar age. However, the incidence of CVD increases greatly after the menopause. The risk of heart disease is strongly associated with the health of an individual's blood vessels. It is thought that changes to the type of fat the investigators eat in their diet may affect the normal functioning and elasticity of the blood vessels, as well as affect cholesterol levels in the blood. Types of fat in the diet include monounsaturated fats (found mainly in olive oil), n-6 polyunsaturated fats (found mainly in sunflower oil) and saturated fats (found mainly in dairy products, such as butter and cheese). Since the investigators are in the fed (or postprandial) state for up to 18 hours of the day, it is important to see how these different fats affect the investigators blood vessels and blood fats over the course of the day after eating a meal. The aim of this study is to determine how consuming meals rich in saturated fats, n-6 polyunsaturated fats or monounsaturated fats influence the normal functioning and elasticity of the blood vessels throughout the day in postmenopausal women. A secondary aim is to determine the effects of these different dietary fats on a range of accepted heart disease risk markers including circulating levels of fats (lipids) and glucose in the blood.