Why do trans fat and saturated fat get such a bad rap?

Perp No. 1: Saturated Fats

Little kids need fat in their diets more than adults do for things like brain and nervous system development. That's why they down whole milk and gobble up cheese cubes.
Little kids need fat in their diets more than adults do for things like brain and nervous system development. That's why they down whole milk and gobble up cheese cubes.
Jean Louis Batt/Getty Images

Fat is good for you. Necessary for your health, even. When we eat fat that we obtain from plants or animals we supply the body with energy. Those ­calories we obsess about really are pure energy. Without them, we wouldn't have the gusto to chase the ice cream truck down the street. Fat also helps the body with other important functions, such as absorbing vitamins, controlling blood pressure and keeping us warm. In toddlers, fat is critical for development of the brain, the immune system and those pinchable, cherublike cheeks.

As we get older, though, we often consume more fat than we burn, and we get, well, fat. When we become overweight, getting into last year's jeans should be the least of our worries. Excess fat contributes to coronary heart disease, which can result in heart attacks or strokes. Storing too much fat also increases your risk of developing type 2 diabetes, gallbladder disease and even cancer [source: MedlinePlus].

But why exactly is saturated fat bad? You have two types of cholesterol -- LDL, the low-density lipoproteins usually known as the bad kind, and HDL, the high-density lipoproteins simply known as the good kind. While some fats, such as monounsaturated or polyunsaturated fats, don't raise your LDL level, saturated fats unequivocally do. Saturated fat raises our bad cholesterol level more than anything else we put in our bodies. These fats are generally solid at room temperature and earn their name from the fact that the fat molecule's carbon atoms are saturated with hydrogen atoms.

Saturated fats are naturally occurring and can be found in foods such as that marbled steak on your plate, the skin on your cooked chicken and the whole milk filling your glass. The problem is that not only do saturated fats raise your cholesterol level; they're usually found in foods that already have cholesterol in them, such as cheese, ice cream and beef.

Health experts advise limiting your intake of saturated fats to 7 percent of your total calories, or about 16 grams a day [source: AHA]. To put this in perspective, 1 tablespoon of mayonnaise has 1.5 grams of saturated fat, 1 cup of whole milk has 5 grams of saturated fat and, if you fix yourself a treat in the form of a breakfast sandwich with egg, cheese and sausage, that sandwich alone will have about 18 grams of saturated fat.

As you can see, one tasty breakfast can put you over the recommended daily limit. Cutting down on your intake of butter, margarine, whole milk, cheese and lard doesn't seem too difficult, but it's tricky because so many products are made with at least one of those ingredients. While it's easy to eliminate a daily piece of pie or leg of lamb from your diet, you should also keep an eye on cheese pizza, chocolate, pastries and breads.

Cooking with coconut oil or palm oil will also increase the amount of saturated fat in a meal. Try to use vegetable oils such as corn oil, olive oil or sunflower oil because these items contain unsaturated fats. Unsaturated fats won't send your cholesterol through the roof. In fact, they don't raise it all and may even lower it a little. Replacing some of the meats you eat with fish, beans and nuts will also lower your total intake of saturated fats.

In the next section, we'll talk about another type of fat that wholly deserves its bad rap -- trans fat.