There's something that every food you buy has in common: The nutrition label. Do you read it? We have come to expect certain brands or types of foods to just be healthy without paying any attention to whatever they are actually made from. Just skimming through the percent daily values (%DV) is not enough to truely tell how good or bad that food may be for you. If a food has a small enough quantity of a nutrient, you will see it listed as 0 grams. But if there really is just the small of an amount, then surely it is not significant and might as well be zero, right? Consider this: What if everything you ate throughout the entire day had 0.1g of trans fat. It will not be long before you have accumulated a much larger quantity. Furthermore, your body is affected by even the smallest amount. The affect will be correlated with the amount you consume, but considering the trans fat example again, if you live by the "a little bit won't hurt me" principle, then you are probably consuming more than "a little bit."
In this content section you can read about how to identify the different kinds of fats as good or bad. Then see first hand examples of how "healthy" foods can sneak in minimal amounts of some pretty bad stuff in
Health Foods that Really Aren't (some the ingredients actually counteract the ways the product claims to be good for you).