The World Turned Upside Down: The Second Low-Carbohydrate Revolution (24 page)

Chapter
13

Hunger.
What it is.
What to do about it.

The reporter from Men's Health asked
me:
"You finish dinner, even
a satisfying low-carb dinner" – he is a low-carb person himself – "you
are sure
you ate enough but you are still hungry. What do you do?" I gave him
good
advice. "Think of a perfectly broiled steak or steamed lobster with
butter,
some high protein, relatively high-fat meal that you usually like. If
that
doesn't sound good, you are not hungry. You may want to keep eating.
You may
want something sweet. You may want to feel something rolling around in
your
mouth, but you are not hungry. Find something else to do – push-ups are
good.
If the steak
does
sound good, you may want to eat. Practically speaking, you might want
to keep
hard boiled eggs, kielbasa, something filling, around (and, of course,
you
don't want cookies in the house)." I think this was good practical
advice. It
comes from the satiating effects of protein food sources, or perhaps
the
non-satiating, or reinforcing effect of carbohydrate. But the more
general
question is: what is hunger?

We grow up thinking that hunger is
somehow
our body's way of
telling us that we need food but for most of us that is not the case.
Few of us
are so fit, or have so little body fat, or are so active, that our
bodies start
calling for energy if we miss lunch. Conversely, those of us who really
like
food generally hold to the philosophy that "any fool can eat when
they're
hungry." Passing up a really good chocolate mousse just because you are
not
hungry is like .. well, I don't know what it's like. Of course, if you
are on a
low-carb diet, you may pass it up for other reasons, or at least not
want to
eat too much.

Getting to the point here, if I
presented
you with a multiple choice
question that asked what hunger is, the answer would be "all of the
above." We
feel hunger when we haven't eaten for a while. We may feel hunger if
the food
looks good or if we are in a social situation in which eating is going
on, the
spread of
petits fours
that were in the lobby at the break in an obesity conference, the
congressional
prayer breakfast or the Pavlovian lunch bell.

Or we may eat because we think it is
time
to eat. This point was
made by the Restoration poet and rake, John Wilmot, Earl of Rochester.
Rochester is famous for his bawdy poetry which is raunchy even by
today's
standards (you must be over eighteen to
follow this link
) but his
Satyr against
Reason and Mankind
makes fun of dumb rules and phony reason:

My reason is my friend, yours
is a cheat;

Hunger calls out, my reason
bids me eat;

Perversely, yours your
appetite does mock:

This asks for food, that
answers, "What's
o'clock?"

This plain distinction, sir,
your doubt secures:

'Tis not true reason I
despise, but yours.''

Figure 13-1
.
Johnny Depp as the Earl of Rochester (
The Libertine
,
2004).

Americans have not conquered this
problem and may have made
it worse. A diet experiment invariably includes a snack as if it has
the same
standing as breakfast, lunch and dinner, the first of which is itself
of
questionable generality. Visitors remark on how Americans are eating
all the
time, not just at meals. If you do that, it doesn't take long until you
are
hungry all the time.

Different people have different
response to external cues.
In experiments in which subjects are interrogated but incidentally have
snacks
available, it is not surprising that thin people regulate their intake
by the
clock on the wall. Overweight people, in distinction, are less
sensitive to
this input and dip into the snacks even if "it's almost dinner time."
Similarly, at the Union Theological Seminary in New York, the school
for
training Rabbis, it is the overweight students who adhere better to
fasting on
high holy days. Consumption is less connected to internal (physiologic)
cues
and external (religious) reasons can have control.

The psychologist B. F. Skinner
[74]
described the problem in a typically dense way.

"I am hungry" may be equivalent to
"I have
hunger pangs," and if the verbal community had some means of observing
the
contractions of the stomach associated with pangs, it could pin the
response to
these stimuli alone. It may also be equivalent to "I am eating
actively." A person who observes that he is eating voraciously may say,
"I really am hungry," or, in retrospect, "I was hungrier than I
thought," dismissing other evidence as unreliable. "I am hungry"
may also be equivalent to "It has been a long time since I have had
anything to eat," although the expression is most likely to be used in
describing future behavior: "If I miss my dinner, I shall be hungry."

What he is getting at here is that
whatever the actual
causes of eating behavior, the behavior itself may
precede
the description of the "motivation
to eat." In other words, we tend to identify a feeling that is
associated with
eating behavior as the
cause
of the behavior.

"I am hungry" may also be
equivalent to "I
feel like eating" in the sense of "I have felt this way before when I
have started to eat." It may be equivalent to... "I am thinking of
things I like to eat" or "I am 'eating to myself.'" To say,
"I am hungry," may be to report several or all of these conditions. .
. ."

The point is that "hungry" only means
you are in a situation
where you are used to eating. It doesn't mean that feeling hungry will
make you
eat, or, more important, that you have to eat.

Lessons from Vagotomy

The vagus nerve contains many nerve
fibers that provide
communication between the brain and other parts of the body (a nerve is
a
collection of nerve cells or neurons whose long extensions or axons are
referred to as fibers). Cells that send signals from the brain to
distant
organs are called
e
fferent
(pr. Ee-fer'-ent). Efferent fibers in the vagus nerve regulate the
digestive
tract – enlargement of the stomach, secretions from the pancreas,
change to
accommodate a larger volume of food (known to doctors as
accommodation).
However, most of the fibers in the vagus nerve are sensory afferents (
a
fferents
carry
information from the body to the brain) providing sensations of satiety
and
hunger as well as feeling of discomfort when we are full.

Vagotomy, cutting the vagus nerve,
was practiced as a means
of controlling ulcers and is still a target, at least experimentally,
for
treating obesity. A surgeon, Dr. John Kral in the Department of Surgery
at
Downstate who had performed such operations described to me how
patients
complained that they had lost their appetite. He had to explain to them
that
you do not have to eat all the time, that nothing will happen if you
miss a few
meals.

Hunger is a signal that you are used
to eating in a
particular time or situation. You are not required to answer the signal.

"You eat because you
are fat."

In trying to go beyond energy
balance, there is a tendency
to think of hunger in terms of hormones, emphasizing regulation by the
hypothalamus analogous to temperature regulation. The hormones are
referred to
as orexigenic, increasing appetite (from the Greek; the Greek
equivalent of
bon appetit
is
kali
orexi
), or
anorexigenic, depressing appetite. While this is part of the picture,
in the
analysis of eating, it leads to some confusion because the endocrine
approach emphasizes
hormonal
output
from the fat cell and, in some sense, bypasses the question of how the
fat cell
got fat in the first place, that is, it bypasses metabolism. More
important, in
the end, for animals and humans outside of a laboratory setup, behavior
trumps
hormones. The analogy is also not entirely accurate in that animals
(and
humans) regulate their temperature hormonally only to a small extent.
The major
control of temperature is behavioral: we put on clothes and we hide in
caves. '

An important aspect of this problem
is the
attempt to understand
the error in "a calorie is a calorie." One critique of the energy
balance model runs something like this: dietary carbohydrate
→
insulin
→
(other hormones
→
) increased appetite
→
greater consumption. In
the extreme case, some explanations might boil down to "you don't get
fat
because you eat; you eat because you got fat" On the face of it, it
doesn't
make any sense (which is why I am not attributing it to anybody in
particular).
It sounds like one of the seemingly profound academic aphorism that
Woody Allen
was so good at parodying: "All of literature is just a footnote to
Faust. "
I understand that it implies that the hormonal secretion from adipose
tissue
encourages eating. But again, it does not tell you why you got fat in
the first
place. It mixes up metabolism with behavior and has implicitly accepted
the
idea that calories are what count, that is, macronutrients affect how
much you
eat (total energy), rather than how it is processed. Although
macronutrients
clearly differ in satiety, regardless of your hormonal state, if there
is no
food, you will not increase consumption. Also, the effects of insulin
are not
so clear
cut.
Whereas
metabolically, insulin is anabolic, at the level of behavior it is
probably
anorexigenic in most cases.

Why do we get fat? We get fat because
we
eat too much of the
stuff that encourages excessive weight gain. We don't know what that is
but we
know that it is not fat
per
se
. Given the unambiguous effectiveness of
carbohydrate restriction
in
reducing
excess weight, it would be surprising if carbohydrate weren't a big
part of the
picture.

The so-called metabolic advantage,
less
weight gain per calorie,
where it exists, is a metabolic effect. The most likely mechanism is
that, due
to the effect of insulin on rates of reaction, anabolic (storage) steps
may
increase accumulation before competing feedback (breakdown) can catch
up.
Explained in the
next
chapter
, it rests on non-equilibrium
thermodynamics
[75]
, which
recognizes the importance of rates as well as
energy.

What Can you do about
it?

The suggestion at the beginning of
this section was to make
sure you know what kind of hunger you are talking about. In this,
behavioral
psychology stresses the difference between "tastes good" and the
technical
term, reinforcing, which only means that the food increases the
probability
that you will keep eating. Anecdotally, we all have the experience of
somebody
(else?) saying "I don't know why I ate that. It wasn't very good."

However little you have to eat to
answer feelings of hunger,
it is certainly bad advice to eat if you are not hungry. Professional
nutritionists, even the Atkins website, are always telling you to have
a good
breakfast. Why you would want to have a good anything if you are trying
to lose
weight is not easy to answer. They say that you will eat too much at
the next
meal as if, in the morning, you can make the rational decision to eat
breakfast
despite no desire for food while, at noon, you are suddenly under the
inexorable influence of urges beyond your control. More reasonable
might be:
"if you find that you eat too much at lunch when you don't eat
breakfast,
then.." but that is not the style of traditional nutrition.