There was a lot of scientific information to wade through, as much as the author tried to keep it simple--and to be honest, a lot of it went out much more quickly and easily than it went in--but there were a few points that made an impression I'm not likely to forget anytime soon.
For one thing, I'm seeing the brain as a processor, not of data, the way the mind is, but of chemicals. The brain is not an instrument of intelligence (although it functions in a highly organized, brilliantly efficient manner--at unimaginable speed); it's a manager of substances. Everything we eat is made up of a dizzying array of separate compounds, and to the degree that they succeed in crossing the "blood-brain barrier," these compounds impact the way the brain responds (and the way we subsequently feel). The faster a substance can cross this barrier and enter the brain, the greater the impact, because this means that a large dose will be delivered at once.
Whatever substance enters the brain regularly (and especially copiously), the brain comes to recognize and regard as "normal." For example, the brain runs primarily on glucose, so the presence of glucose in the brain is normal. When some time has passed since our last meal, our blood sugar level begins to drop, and glucose starts to become scarce in the brain, so the brain sends us craving messages we recognize as hunger. We respond by hunting down some food--either something sweet, or something that the body can synthesize glucose from. That's all very nice, but the same holds true of other substances that enter the brain in sufficient quantity and frequency--like nicotine, or amphetamine. The brain begins to regard the presence of these substances as "normal," and when they are depleted, the brain will send craving messages that they need replenishing (with no regard, by the way, for our health, safety, finances, relationships, or freedom). This is what addiction is. Once a period of time has passed in the absence of these substances, the brain is fully capable of readjusting to the new "normal," and will no longer send us out to score them.
Here's the main point I came away with: Since everything we ingest acts upon the brain like a drug, we can consider any type of food as one drug or another, with specific effects in the brain. We can become addicted to a food simply by consuming it regularly--to the extent that the compounds in that food cross the blood-brain barrier, these will become "normal," and hence, "needed." Similarly, if we refrain from eating those foods, after a period of withdrawal, their absence will also become normal (and not needed). Essential nutrients are excluded from this formula, because the body actually does need them in order to function properly, and cannot synthesize them, so we must obtain them from our diet, but these are relatively few (9 amino acids, 14 vitamins, 17 minerals, and 2 fats).
Why is this important? Well, think about the implications of having your brain considering the components of certain foods "normal" in exactly the same way as it might, say, cocaine. Those foods might not be all that helpful in maintaining optimum health--they may even be contributing to disease. But the brain is simply reading our continued ingestion of these compounds as just the right thing to do. Freaky, huh? See why I finally understood that the brain is not the seat of intelligence, but rather a processor of chemicals?
This is the good news: We are not our brain, and we don't have to be enslaved to any particular food (as long as we can find those few essential nutrients elsewhere). Just as we can detox from an addictive, destructive drug, we can detox from an addictive, destructive food. All it takes is a little attention to nutritional facts, and the will to live well. And it helps if we're trying to live consciously (the subtler, more fundamental definition of "well").
It may be challenging to switch from destructive food to constructive food, because our mind, which processes data with the same blind indifference as the brain processes chemicals, will be telling us to keep on eating the stuff that's fattening, sickening and killing us. It will be interpreting "tastes good" as "must eat," and "different" as "suspect." But just as the brain becomes accustomed to a new substance that shows up regularly, the mind will get on the bandwagon eventually--if we keep at it. We can, in fact, retrain our desires and our tastes. We don't have to do as we've always done, just because the advertising led us that way. We can uncouple ourselves from all the influences that don't serve us well and decide for ourselves what we want to do (and eat). How cool is that?