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especially carbohydrates. Call it applied reductionism. Humans have been
refining grains since at least the Industrial Revolution, favoring white
flour (and white rice) even at the price of lost nutrients. Refining
grains extends their shelf life (precisely because it renders them less
nutritious to pests) and makes them easier to digest, by removing the
fiber that ordinarily slows the release of their sugars. Much industrial
food production involves an extension and intensification of this
practice, as food processors find ways to deliver glucose - the brain's
preferred fuel - ever more swiftly and efficiently. Sometimes this is
precisely the point, as when corn is refined into corn syrup; other
times it is an unfortunate byproduct of food processing, as when
freezing food destroys the fiber that would slow sugar absorption.

So fast food is fast in this other sense too: it is to a considerable
extent predigested, in effect, and therefore more readily absorbed by
the body. But while the widespread acceleration of the Western diet
offers us the instant gratification of sugar, in many people (and
especially those newly exposed to it) the "speediness" of this food
overwhelms the insulin response and leads to Type II diabetes. As one
nutrition expert put it to me, we're in the middle of "a national
experiment in mainlining glucose". To encounter such a diet for the
first time, as when people accustomed to a more traditional diet come to
America, or when fast food comes to their countries, delivers a shock to
the system. Public-health experts call it "the nutrition transition",
and it can be deadly.