When I started cutting dairy out of my diet, one of the effects was that I was eating a lot less fat. I joked to John that I would probably lose a lot of weight if I kept it up! It's a joke because I really don't care if I lose weight or not. I'm still about 10 lbs. up from my pre-pregnancy weight, but I'm still a healthy weight so I don't really let it bother me. (I'm more concerned about the flabbiness of my abs -- yikes!)
But less than a day in, I was already suffering. I ate and ate and ate -- carbs. I wanted fat. The thing about carbs is that an hour or two after you eat them, you're already starving again! (Particularly for me, since I have a very fast metabolism.) Rice milk is sweet, so it seems like it's hitting the spot, but pretty soon you have to go drink more because it doesn't really satisfy. I craved sugary food. I was eating much more than I usually do, feeling hungry all the time, and getting headaches.
Once I added dairy back in, I felt better almost instantly. There are so many different dairy products that you can eat, in so many different combinations. But I also found I was satisfied much more easily. A half cup of rice with sour cream and cheese is so much more satisfying than a half cup of rice with sugar and cinnamon, or with just salt. I ate less frequently. I made a batch of shortbread -- just flour, butter, and sugar -- and really enjoyed it, but after eating a few pieces, I found I didn't want to eat any more. I was satisfied. This is pretty amazing coming out of a person who has been known to polish off a whole box of cookies in a sitting. (Not a proud moment. John's comment: "It was like a wheat harvester.") I have a very hard time stopping eating sweets. But that shortbread, rich as it was, was satisfying even though it was comparatively low in sugar.
All this makes sense if you understand a bit about fat. Fat contains 9 calories per gram, whereas protein and sugar both contain 4 calories per gram. So, if you're eating fat, it's true that you should eat half as much. However, it also is slower to digest and sits heavier in your stomach, making you feel more satisfied with less.
Fat also carries flavors throughout the food. Have you ever added curry to a chicken dish that contains a little fat? The curry gravitates toward the fat, turning it bright yellow. The same holds true for most spices. Everyone knows that the cure for a burning mouth after eating a jalapeno pepper is a drink of whole milk. The fat in the milk carries the spicy oils away from your tongue.
This is why low-fat foods can often be very deceptive. In order to make them palatable while removing all the fat, the manufacturers usually add sugars. Why are we finding sugar in spaghetti sauce, in lasagna, in crackers? Because sugar tastes good, so it makes the food palatable despite the lack of flavor-enhancing fat. Next time you want to buy a low-fat substitute for a high-fat food, read the ingredient label and see what they've added to make up for the fat. Chances are, the grams of sugar will be much higher even though there are fewer grams of fat. Other commonly added ingredients are carrageenan, a thickener; MSG; and extra salt.
Dieters often cut out fat in the assumption that dietary fat produces belly fat. But that's not necessarily true. High blood sugar often produces belly fat, as the body tries to dump unwanted glucose by converting into fat. And high blood sugar often comes from the rush-and-crash cycle we get when eating too many carbs -- something dieters often do in the urge to quell their feelings of starvation and deprivation. A mix of carbs (particularly complex carbohydrates), protein, and fat will help stabilize the blood sugar, as carbs enter the bloodstream first, protein enters later, and fat enters last.
I read recently that some tribes of North American Indians knew of a disease called "rabbit starvation," wherein a person could eat all the (lean) rabbit meat he wanted and yet still feel constantly hungry and eventually starve. This is anecdotal, of course, but it jives with my experience of eating almost no fat and being hungry all the time.
If fat is to blame for all the obesity and high blood pressure and heart disease in this country, why is it that those disorders are rampant now and were rare 100 years ago, when people 100 years ago were eating much more fat? I don't have an answer, but I have a feeling that a more balanced diet, low in refined sugar and other artificial foods, is probably much healthier than a diet composed of modern, low-fat health foods.
This would also explain why the French and the Italians are so healthy, despite eating loads of foods our American sensibilities suggest are "bad for you." There are whole diet books to help us "eat like the French." But it isn't hard: eat real butter and enjoy it, and you won't feel the need to keep eating and eating. Enjoy bitter, sour, and savory flavors, and you won't crave sugar all the time.
Which fats should we be eating? Probably a varied sampling. Some, but not excessive, saturated (solid) fat; and some unsaturated (liquid) fat, balanced between omega-3's (found in fish and flax oils) and omega-6's (found in most other vegetable oils). The one fat no one should be eating is "trans" fat, which is unsaturated fat made into a solid by artificial means. The body doesn't recognize it, and it seems to cause all kinds of harm. Luckily it is going out of style now that we know how harmful it is. Still, it's best to avoid margarine and other highly processed fats. Peanut butter is another place where hydrogenated fats are found, and I'm afraid it's a habit I have trouble kicking. I was raised on it, and all-natural peanut butter just isn't the same!
One last benefit to fat: it carries the fat-soluble vitamins, such as A, D, E, and K. These can be found in fish oils, butter, vegetable oils, or the fat in wheat germ, but they can't be obtained in the diet without at least some fat. (However, vitamin D is also produced by the skin, and vitamin K by intestinal bacteria.)
I'm not saying you should be going out and eating spoonfuls of lard as a health food. But a reasonable amount of fat -- for instance, the amount that occurs naturally in food -- is part of a good diet for a normal, healthy person. Vegetables go down well with butter, which also aids in the absorption of its vitamins. Meat tastes better when not patted completely dry. A little olive oil is delicious on a salad, and complements its nutrition. Whole milk tastes better than skim, and it provides more vitamins.
Edited to add these links, suggested by Ryan:
The New York Times: What if it's all been a big fat lie?
Mark's Daily Apple: Fats
Four Hour Work Week: The science of fat loss: why a calorie isn't always a calorie
The first one, in particular, I highly recommend. Lots of information I hadn't heard before.