One of the interesting parts of the rationale for the proposed nutrition labels is that "calories from fat" will be eliminated as a category, since the type of fat is more important than the amount. This is actually a huge departure from the mentality that our country has had for years - that fat is bad. We've been fat-phobic for generations, with a myriad of "fat free" and "low-fat" labels slapped on every food product for miles.
So why have we not been any healthier as a population as a result? That's obviously a larger question than I can answer here, but there are several reasons why "fat free" and "low-fat" options are not always the way to go.
First, taste. I mean, have you ever tried to eat fat
free "cheese"? I can't even write cheese without the quotes there
because it's obviously some laboratory science experiment when cheese
doesn't melt and tastes like silly putty. Blech.
More important, though, is nutrition and health. When items need a label to tell you their healthy qualities, they usually aren't that healthy. This is why they don't put a "fat free" label on apples. You typically see the label on dairy products and packaged foods of one kind or another. Products that need to be "health washed," like fat free cookies or chips are ones you should stay away from in general, so there's no point in eating the fat free variety. A fat free Cheez-It is still a Cheez-It. There is also research that shows that a hormone produced by fat cells can help send satiety signals to your brain. So when you binge on a whole bag of fat free cookies and justify it by saying "they were fat free!" that could be part of the problem.
Your body needs fat to function. It helps to absorb vitamins - fat soluble A,D,E and K, specifically. It contains things like omega-3s and omega-6s, essential fatty acids that help with brain function and mood (and which you can only get from food). Low-fat or fat free diets also lower your HDL (referred to as "good cholesterol"), which your body needs to be high to help fight heart disease.
There's a gentle balance to a healthy diet between carbs, fat and protein. Usually if you drastically reduce one, you jack up another. (Hence the crazy popular diets like Atkins or South Beach.) Most fat-free snacks are insanely high in carbs, which have their share of issues as well. Sometimes when you cut out fat in dairy and meat, you are also reducing your protein, especially if you don't make up for it in other sources.
As a side note, I find it interesting that people freak out when I say I drink whole milk. But that's so fattening!, they say. They then go on to tell me they drink 2% milk. Well, whole milk is 3% fat. Not 100% fat. And more studies are showing a correlation between whole dairy products and reduction of body fat. Not that you should go nuts with the whole fat dairy. Or some red meats, which can be high in saturated fat.
Choosing good fats, like poly and mono unsaturated fats and limiting saturated fats (and not eating any trans fats, which you usually find in processed foods) is the key. I use real butter, not margarine. (Really the only thing margarine is good for is a lubricant to help you remove a tight ring from your finger or grease up the bottom of a sled.) I just don't use it all the time. You don't get high cholesterol by eating a tablespoon of butter or having a serving of whole milk or three ounces of steak. The key, like many things in life, is balance and moderation.