Though grilling and boiling is a tasty option to cook your meats, it's not as healthy as cooking in water. A chemical process occurs when you cook proteins and sugar without water that produces AGE's - or advanced glycated endproducts. It seems fitting to labeled them AGE since they cause DNA damage which is basically what happens when we age. Think of what happens to your food when you cook without water. They brown. AGE's are concentrated in bread crust, browned meats, char-broiled fish, you get the point.
Because oils are susceptible to rancidity when exposed to heat, it is important not to cook with an oil with a low smoke point and not to cook over an oil's smoke point - the temperature at which the oil starts to break down. At this point, the heat will cause oxidation in the oil, destroying the protective properties of the oil. Imagine the process of iron turning to rust and that playing out in your food and eventually damaging your cells. This would be counter-productive to eating good quality oils.