I make a lot of casseroles and stews, using both mince and diced meat but rarely, if ever have any fat on top of the dish after it has cooled. Is there a lot of fat on the meat you are using, in which case, just cut it off before you cook.
We all need some fat in our diet. Fat helps you absorb vitamins A, D, E, and K, the so-called fat-soluble vitamins. Fat also fills your fat cells and insulates your body to help keep you warm. The fats your body gets from your food give your body essential fatty acids called linoleic and linolenic acid. So do not to keen to eliminate all the fat in your food.
An excess of any food type is likely to do you harm. I have always used butter. I have yet to find an alternative I like and I think unless you do eat out of the frying pan, you are unlikely to consume damaging quantities of saturated fats.