Fats, they are added to foods for flavor and taste. Some people eliminate them all together while others don't know where to draw the line. To tell you the truth, not all fats are created equal. First, let me explain the chemical composition of fats. Below you will see the general structure of fats (a glycerol backbone and 3 fatty acid chains attached...a little over your head at this point, lol).
Now here is how the structure plays into what fats are good and which ones are bad.
Saturated Fats: As you can see in the structure above this fat is "saturated" because it has the maximum amount of hydrogens present on its fatty acid chains. This means that saturated fats are easy to pack in our bodies. This is why a diet high in saturated fats causes plaque buildup in blood vessels and causes all kinds of cardiovascular problems. These fats are found in solid form at room temperature and are found in butter, lard, deep-fry oils, shortening, and heavy cream. Basically saturated fats are found in dairy and animals.
Trans Fats: trans fats have gone under a chemical process known as hydrogenation which basically takes unsaturated fats (better for you) and converts them into saturated fats. These fats are then called trans fatty acids. Trans fats are even worse for you than saturated fats. Trans fats are commonly added to boxed food, cookies, etc. to increase its shelf life. If you see "partially hydrogenated oil" then steer clear of this food.
Cholesterol: Our liver makes cholesterol so it is not needed in our diet. Cholesterol is found in animal products. For example an egg yolk contains about 200 mg of cholesterol. There are two types of cholesterol: HDL and LDL. LDL is the "bad cholesterol" and HDL is the "good cholesterol." By eating a lower fat diet and exercising you can help lower your bad cholesterol and increase your good cholesterol. A simple blood test can determine your cholesterol levels in the blood. Cholesterol is important in the body but our body can make enough of it; try to aim to eat no more than 300 mg of cholesterol.
Better for you Fats:
Unsaturated Fats: these fats have double bonds in them and do not have the maximum amount of hydrogens possible. This means that they are liquid at room temperature. These fats are not as likely to block arteries. Unsaturated fats are found in most nuts, olive oil, canola oil, soybean oil, etc. These are healthier options compared to saturated and trans fats.
Essential Fatty Acids: I am sure you have all heard of Omega-3 and Omega-6 fatty acids. These are unsaturated fatty acids found in fish, some vegetable oils (soybean and canola), plants (flax), soybeans, etc.
Fat is not always the enemy. Yes, it helps cushion our organs and give us insulation but too much fat can lead to excess weight, clogged arteries, cardiovascular problems, etc. In general fats have to be consumed in moderation of course. You should aim to make about 20-35% of your diet each day come from fats. Remember to choose healthier fat options as we discussed above. Stay away from trans and saturated fats as much as possible. Fats provide 9 kcal/gram so be careful not to overdue it!