As a society, we have developed a fear of fat in our quest to stay healthy and lose weight. The low-fat movement, which arose in the 80's, is what started this trend. In order to make foods still taste good after the fat had been reduced, food makers replaced the fat with sugar. The problem, then, became that sugar was actually more of a culprit in fat accumulation and weight gain than fat was! So, in reality, the products didn't become any healthier by becoming "low-fat".
Our bodies need a particular amount of fat, but healthy fat. Proper amounts of healthy fat are a good addition to our diet. Examples of healthy fats are avocados, nuts and nut butters, seeds, olives and unrefined oils such as coconut oil, olive oil and flax seed oil.
We need to be especially careful of trans fats when evaluating the types of fats that we consume. The omega-3 fatty acids in liquid oil cause it to go rancid rather quickly. So to prolong the shelf life of various processed and packaged foods, liquid oil is converted into a solid through the partial hydrogenation process. Think about the fact that trans fats are prolonging the shelf life of some foods. Then we ingest those foods. What might that be doing to your body? What does it do to YOUR shelf life?
Fortunately, food makers are now required to report the amount of trans fats on the nutritional labels of their products. Any amount less than .5 grams of trans fats will translate to zero on the label. So to be sure that the product is free of trans fats, check the ingredient list for hydrogenated or partially hydrogenated oils. Also be aware that many restaurants use trans fats to fry their foods.
I challenge you to start reading labels and see what the labels in your house say. It might be unrealistic to completely rid your house of trans fats overnight, but being aware is the first step. Once you are aware, then you can take baby steps to try and reduce or eliminate the amount of trans fats that you are consuming.
In an effort to be semi-brief, I have only scratched the surface of all the information out there on different types of fats. If you are interested in reading more, I found the following article to be quite comprehensive on the topic.