Not ALL fats are bad.  Mono-saturated and poly-unsaturated fats can actually lower cholesterol and improve heart health.

You need fat to help transport the fat-soluble vitamins such as A, D, E, & K, across the cell membranes.

Our cell membranes are made up  of fat.

Brain cells have the highest concentration of fats (about 60%).

Eating high levels of saturated fats increase our desires for sugar and carbohydrates.

Be careful of processed or partially hydrogenated oils and margarines.  Many times that process actually will make a polyunsaturated fat saturated, and include additives and preservatives that are more harmful to you.  A low fat option...take one pound of butter, add 1/4 cup of water and blend well with a mixer.  Store this in a sealed container in the fridge.  This should not be used for baking due to the increased amount of water. Another lower fat option is to mix 1 cup softened butter with 1/4 cup of canola oil and mix with mixer until smooth.  This can be used in cooking and baking.   Store this in the fridge as well. Both of these reduce your saturated fat while providing a  "spread" that is better tasting than any margarine.  Low fat and diet margarines often have water added to them.  This way you actually use less "fat".  A very YUMMY recipe for butter is to mix 1 pound of butter with  1/4 cup of honey or molasses. This is great on bread, roles, pancakes and biscuits!  (I know that butter is a saturated fat, but, most margarines are hydrogenated and have further additives.)

Many people think that saturated fats are only animal fats, such as found in marbleized red meats, poultry and fish skin.  Vegetables can also be a source of saturated fats.  A hint here...if the fat is solid at room temperature, it's a saturated fat and should be used sparingly or avoided.  Palm oil, palm kernel oil, coconut oil and cocoa butter have a much higher percentage of saturated fats than eating a double hamburger from your favorite fast food restaurant.