Whether one wants to lose weight, gain weight, or just be healthy, the concept of caloric density is an important one to understand.
The caloric density of a food is the numbers of calories that are contained in 1 gram of that food. For instance, brown rice has a caloric density of 1.2, which means that brown rice has 1.2 calories per gram.
That's a relatively low caloric-density food. Most fruits and vegetables are. For instance, an apple has a caloric density of 0.59—it has only 0.59 calories per gram. A carrot is 0.44. A banana is 0.6. A potato is 0.76.
By contrast, a rib roast has a caloric-density of 3.31. A chicken thigh is 2.12. A pork chop is 2.28. Processed meats such as liverworst (3.32) or salami (4.20) are even higher. Bacon is 5.56.
It's a little oversimplified, but largely true: in general, foods from the plant kingdom tend to have low caloric densities and foods from the animal kingdom tend to have high caloric densities.
So what? Why is that important?
Let's take an example: Suppose we want to lose weight but we're eating mostly high caloric-density foods. What this means is that it doesn't take much of such foods to give us a lot of calories. Conversely, if we try to cut down on the calories, we won't feel full. We'll feel hungry. And eventually, that will cause us to leave the diet and binge, gaining back whatever weight we've lost.
If we want to lose weight, the smart thing to do is to eat mostly foods of low caloric density, like fruits and vegetables and grains, not just as a temporary diet but as a lifetime diet.
These foods also just happen to be, in countless epidemiological studies, the healthiest foods—and also the foods eaten by the four healthiest peoples in the world (the Hunzas, Vilcabambans, etc.).
But I should mention a very interesting phenomenon whereby foods of low caloric-density (CD) get transformed into high caloric-density foods: In general, it's when foods get ground up or refined.
For instance, potatoes, as mentioned before, have a caloric density of 0.76. But when ground up into potato flour and made into potato pancakes, the CD goes up to 6.51. Wheat bread (where the grain has been ground) has a CD of 2.61.
And, too, fats often get added into foods made of ground-up grains. Thus crackers have a caloric density of 4.46. Corn muffins have a CD of 4.14. And so on.
In fact, corn provides a very good illustration of this phenomenon. Corn as corn kernels or corn-on-the-cob, whether fresh or steamed, has a caloric density of only 0.92. You can eat a lot of fresh corn without gaining weight (as well as adding to your health).
But corn bread has a CD of 4.27, a taco shell has a CD of 4.55, and corn chips have a CD of 5.46. See the difference? You don't have to eat much of those before you've started packing in the calories.
In general, grains (and foods in general) are best eaten in the whole state. Besides the issue of caloric density, there are other issues, such as rancidity. As soon as a grain is ground, for instance, its germ is exposed to the air and it begins to go rancid. (Or the germ and bran are refined out, as in white flour, in which case the food loses nutrients and becomes an "empty-calorie" food.)
On the whole, then, we'll be healthier and trimmer if we eat our grains (and foods) in their whole form, such as when we cook brown rice or millet (or eat a baked potato instead of french fries or chips). This is only a subset of the more general principle that foods are healthiest in their unrefined state, that is, when they're closest to the way nature made them.
—jim sloman, for 2/18/02