I've saved carbohydrate
for last because it's the food group that affects blood sugar most
profoundly—both by eating it and by not eating it. If you're like
most diabetics—or even most inhabitants of industrialized
countries—you probably eat a diet that's mostly carbohydrate.
Breakfast cereal. Grains. Fruit. Bread. Cake. Beans. Snack foods.
Rice. Potatoes. Pasta.
No doubt you've heard the
endless talk in the popular media about carbohydrate. Books tout the
value of a high "complex carbohydrate" diet. Athletes
"carbo-load" before big games or marathons. TV and radio
commercials extol the virtues of Brand X sport drink over Brand Y
because it contains more "carbos."
What if I, a physician,
told you, a diabetic, to eat a diet that consisted of 60 percent
sugar, 20 percent protein, and 20 percent fat? More than likely, you'd
think I was insane. I'd think I was insane, and I would never make
this suggestion to a diabetic (nor, in reality, would I even make it
to a nondiabetic). But this is just the diet to which I was subjected
for many years. The ADA made this recommendation to diabetics for
decades. On the surface, these recommendations seemed to make sense
because of kidney disease, heart disease, and our elevated lipid
profiles. But this is what is known as single-avenue thinking. It
seemed logical to insist that dietary intake of protein and fat be
reduced because no one had looked at elevated blood sugars and the
high levels of insulin necessary to bring them down as the possible
culprits.
So if you eat very little
fat and protein, what's left to eat? Carbohydrate.
As I discovered in my
years of experimentation on myself, and then in my medical training
and practice, the real dietary problem for diabetics is fast-acting
and large amounts of carbohydrate, which result in high blood sugars
requiring large amounts of insulin to try to contain them.
So what are carbohydrates?
The technical answer is
that carbohydrates are chains of sugar molecules. The carbohydrates we
eat are mostly chains of glucose molecules. The shorter the chain, the
sweeter the taste. Some chains are longer and more complicated (hence,
simple and complex carbohydrates), having many links and even
branches. But simple or complex, carbohydrates are composed entirely
of sugar.
Sugar? you might ask,
holding up a slice of coarse-ground, seven-grain bread. This is sugar?
In a word, yes, at least
after you digest it.
With a number of important
exceptions, carbohydrates, or foods derived primarily from plant
sources, such as vegetables, grains, and fruits, have the same effect
on blood glucose levels that table sugar does. (The ADA has recently
recognized officially that, for example, bread is as fast-acting a
carbohydrate as table sugar. But instead of issuing a recommendation
against eating bread, its response has been to say that table sugar is
therefore okay, and can be "exchanged" for other
carbohydrates. To me, this is nonsense.) Whether you eat a piece of
the nuttiest whole-grain bread, drink a Coke, or have a dollop of
mashed potatoes, the effect on blood glucose levels is the
same—blood sugar rises, fast.
How can this be?
As noted in the
introduction to this chapter, the digestion process breaks each of the
major food groups down into its basic elements, and these elements are
then utilized by the body as needed. The basic elements of most
carbohydrates are glucose molecules. We usually think of simple
carbohydrates as sugars and complex carbohydrates as fruits and grains
and vegetables. In reality, most fruit and grain products, and some
vegetables, are what I prefer to talk about as "fast-acting"
carbohydrates. Our saliva and digestive tract contain enzymes that can
rapidly chop the longer chains down into the shorter, sweeter chains.
We haven't the enzymes to break down some carbohydrates, such as
cellulose, or "undigestible fiber." Still, even our saliva
can break down starches into the shorter chains and even pure glucose,
on contact.
Pasta, which is often made
from durum wheat flour and water (but can also be made from plain
white flour and egg yolks, or other variants), has been touted as a
dream food—particularly for runners carbo-loading before
marathons—but it quickly becomes glucose, and can raise blood sugar
very rapidly.
In the Type II diabetic
with impaired phase I insulin response, it takes hours for the
pancreas to catch up with the levels of sugar in the blood, and day
after day, during that time, the high blood sugars can wreak havoc. In
the diabetic who injects insulin, there is a tremendous amount of
guesswork, rarely successful, involved in finding the proper dosage of
insulin and timing it to cover a carbohydrate-heavy meal. Then the
injected insulin doesn't work fast enough.
Some carbohydrate foods,
like fruit, consist of high levels of simple, fast-acting
carbohydrates. Maltose and fructose—malt sugar and fruit sugar—are
slower-acting than sucrose—table or cane sugar—but they will cause
the same increase in blood sugar levels. It may be the difference
between nearly instant elevation and elevation in 2 hours, but the
elevation is still high, and still requires a lot of insulin to bring
it into line. Despite the old admonition that an apple a day keeps the
doctor away, I haven't had fruit in more than thirty-one years, and I
am considerably healthier for it. Some foods, like broccoli, contain
lots of cellulose, or undigestible fiber, which slows the digestion
and dilutes the small amount of digestible carbohydrate they contain.
As noted previously, most
Americans who are obese are overweight not because of dietary fat, but
because of excessive dietary carbohydrate. Much of this obesity is due
to "pigging out" on carbohydrate-rich snack food or junk
foods, or even supposed healthy foods like bread and pasta. It's my
belief that this pigging out has little to do with hunger and nothing
at all to do with being a pig.
I'm convinced that people
who crave carbohydrate have inherited this problem. To some extent, we
all have a natural craving for carbohydrate—it makes us feel good.
The more people gorge on carbohydrates, the more people will become
obese, even if they exercise a lot. But certain people have a natural,
overwhelming desire for carbohydrate that doesn't correlate to hunger.
These people in all likelihood have a genetic predisposition toward
carbohydrate craving, as well as a genetic predisposition toward
insulin resistance and diabetes. This craving can be reduced for some
by embarking upon a low-carbohydrate diet.
Richard
K. Bernstein, M.D., F.A.C.E., F.A.C.N., C.W.S.
