The World Turned Upside Down: The Second Low-Carbohydrate Revolution (28 page)

Living systems are not at
equilibrium. Living systems, in
fact, maintain themselves very far from equilibrium. They are
characterized by
an in-and-out flux of material and energy. In a dietary intervention,
material
fluctuates around a level far from equilibrium. In other words, changes
with
time become important and changes may be controlled by the presence of
catalysts, that is, enzymes, or other factors that affect the rate of
reaction.

Figure
14-6
shows the
theoretical fluctuations of fat within a fat cell. The key idea is that
the
reactions, breakdown and re-synthesis, are very far from equilibrium
where you
would have little fat, mostly fatty acid.

Looking at fat gain and loss (
Figure
14-6
), adipocytes cycle between states of greater or
lesser net
breakdown of fat (lipolysis and re-formation) depending on the hormonal
state
which, in turn, is dependent on the macronutrient composition of the
diet. A
hypothetical scheme for changes in adipocyte

TAG and a proposal for how TAG gain
or loss could be
different for isocaloric diets with different levels of insulin is
shown in the
figure. The basic idea is that fat fluctuates but if you slow storage
enough
that it hasn't had a chance to break down before you come in with
another meal,
fat will accumulate whatever the caloric input.

Figure
14-6
Hypothetical model for the effect of
insulin on efficiency
of storage. Black line indicates response under conditions of weight
maintenance, fluctuates but averages to no change. The upper blue line
shows
the effect of added insulin on hormone-sensitive lipase activity. The
important
point is that the energy differences are very small compared to the
equilibrium
value, which would be very far below the figure. The system is not
controlled
by energy but by rates.

Under normal control conditions of
weight maintenance, the
breakdown and utilization of TAG follows a pattern of lipolysis
(fasting) and
intake plus re-synthesis (meals). To make it simple, we assume a
sudden,
instantaneous spike in food at meals. Then the curves represents the
net flow
of material within the adipocyte. This averages out to a stable weight
maintenance (lower red dotted line in
Figure
14-6
).
If we keep each meal at constant calories but increase the percentage of
carbohydrate or otherwise generate a higher insulin level, the
hormone-sensive
lipases, the enzymes that break down fat will be inhibited (blue line
in the
Figure). Re-synthesis of TAG is less affected by the elevated insulin
(may
actually slow down). The net effects are changes in the direction of
accumulation
of TAG. It is theoretical but the model shows you how kinetics (how
fast it's
happening) may be more important than thermodynamics.

Summary
.

Metabolic advantage, or energy
efficiency, is not
contradicted by the laws of thermodynamics. The second law is more
important
than the first and it emphasizes inefficiency. There are several
biochemical
mechanisms, thermic effect of feeding, gluconeogenesis and substrate
cycling
that account for the observed variable efficiency which, in humans,
generally
support the advantages of low-carbohydrate diets. Because it is
physically
possible to have variable weight gain and because the experimental
observations
in people favor carbohydrate restriction, it is worth a shot. The
insistence
that only calories count is one of the bad ideas that has held back
research
and limited the ability of individual dieters to get good advice and it
has to
be addressed before we can move on. It is not the only bad idea,
however. These
should also be addressed. Next chapter.

Chapter
15

Summary:
Bad Ideas

A summary so far is that nutritional
thinking has followed two
really bad ideas: "You are what you eat," and "a calorie is a calorie."
If you
want to pick just two things that account for the nutritional mess in
this
country and around the world, these would be it. The ideas are, on the
face of
it, contradictory – if eating fat makes you fat or puts fat in your
arteries,
then fat is bad. If all calories are the same, then fat is neither good
nor
bad.

Bad Idea: "You are what
you eat."

At least unconsciously, people really
do
hold to the idea that
food gets packaged into your body as in refrigerator woman and we
really do go
with the assumption that fat makes you fat and that saturated fat clogs
your
arteries because it is greasy. These ideas are the first thing to get
rid of if
we are to make progress in dealing with nutrition. "You are what you
eat" is
not a real biological idea.
You
are what your body
, that is, your metabolism,
does with what
you eat
is
the better principle. Your body is not a storage container. It is a
machine.
Not one that grinds everything down to calories, but a chemical
machine. The
input to the machine is the digestive tract but even the digestive
system is
more than simple plumbing.

Within the cells of the intestine,
between
the absorption of food
and the entry into the circulation, transformations are taking place.
The
nutrients that intestinal cells process, for their own metabolism, and
those
that ultimately wind up in the blood may be very different from what
you ate.
For example, the components of protein, the individual
amino
acids
, are re-shuffled and
processed even in the cells of the intestine. The particular
arrangement of
amino acids for particular proteins that is encoded in your DNA
determines the
biologic activity of those proteins. There are about twenty amino acids
all
together. During digestion, protein is broken down to the component
amino acids
which are absorbed. Ten of the amino acids, the essential amino acids,
are
required in the diet. The others are inter-convertible. A re-shuffling
of some
of the amino acids by the process known as
transamination
provides the right mix of
amino acids for any particular protein in any particular tissue. So
this
process of interconversion of amino acids is going on all the time and
as early
in metabolism as the cells of the intestine. Beyond building blocks for
proteins, amino acids take part in metabolism on their own. The amino
acid
alanine, for example, is a key player in metabolism providing carbons
for
gluconeogenesis. Described in
Chapter 6
,
the process connects protein,
carbohydrate and energy metabolism. The amount of alanine leaving the
intestine
is typically three times the amount that came in. Providing amino acids
for
carbohydrate is, again, part of why you don't have to
consume
any; the glucose
that the brain requires can come from amino acids such as alanine or
other
metabolites. G
luconeogenesis
is one of the transformations going on all the time in your body
(mostly in the
liver where Claude Bernard found it originally). Sometimes described as
a "last
resort" for production of glucose, gluconeogenesis, like the
interconversion of
amino acids, goes on all the time. Your body does not need any dietary
glucose.
You are not what you eat.

Also not good: "a
calorie is a calorie."

The previous chapter described how
little
can be expected from
the idea that "a calorie is a calorie," that is, that the energy
(calories)
supplied in food is all the same, that it doesn't matter whether the
calories
come from
Tournedos
Rossini
, Twinkies
^®
or from
whole grain cereal. The implication is that if two people do the same
amount of
exercise, that they will gain or lose the same amount of weight,
calorie for
calorie. Despite arguments of the type we went through, many people
feel that
the idea makes sense and that it is perfectly intuitive. A tip-off on
what's
wrong with the idea that "a calorie is a calorie," is that if the
scientific
evidence really supported it, people wouldn't still be trying to prove
it, and
there probably wouldn't be any professors of biochemistry, not even
one, who
claimed that the idea is false.

Other bad ideas and the
nutrition mess

It's hard not to see a total
nutritional mess in the
population. Most people have the vague idea that eating a low-fat diet
must be
good in some way even though one scientific study after another shows
that this
is not true and the dire predictions on dietary fat have never panned
out. Some
of the experts are backing down on this; the American Heart Association
quietly
removed any recommendation on total dietary fat in 2000. What? You
didn't know
that? Their webmeister doesn't know that either. Their websites, for
example, "The
American Heart Association's Diet and Lifestyle Recommendations" at
http://bit.ly/1nJnjwh continue to recommend low-fat. The AHA is
officially down
only on saturated fat and, of course,
trans
-fats.
The dietary guidelines from the government also say that they don't put
any
limits on total fat but their recommendations are for low-fat milk,
lean meat,
etc. So, low-fat or not low-fat? And if it's not low-fat, why is
everybody
recommending it?

A simple problem.

When people tell you that a problem
is
very complex, there's a
good chance that what they mean is that they don't want to face the
part of it
that is really simple. And a lot of it really is simple. If you look
around,
you see that people are fatter than they used to be. Reliably fatter.
Not everyone.
Not everyplace. Much less in New York City or Vermont. But in what New
Yorkers
call America (starts someplace in New Jersey), people really are
fatter,
sometimes obese. Overweight is a real burden. Not that it's a health
risk the
way they say it is. What the data show is that life expectancy is not
really
dependent on how much you weigh except at the very extremes. It is true
that
the things that make you fat can also make you susceptible to disease
or
metabolic disturbances but weight
per
se
is not a health risk. It is, however, a
tremendous psychological
burden. For many people, it colors their whole life. It's a constant
strain.
Every meal is a battle and there is a constant, unwelcome overtone of
bad vibes
in eating. The sense of control is the key variable. It's not really
your
social life, at least for men. It's not just the subtle prejudice
against fat
people. All those count but it's more that people who might otherwise
have
great ability to plan their daily actions and to determine the course
of their
lives, can't seem to get control over their own body.

The causes are simple. We followed a
false
star in nutrition. The
fat people you see in the mall were encouraged to believe that fat was
an
enemy. Worse, they were encouraged to believe that the things that were
hurting
them, things like bread and potatoes were neutral, were part of life,
were
maybe even "healthy." You may see them eating a sandwich just at the
moment you
think about how everybody is fat.

Most of all, it is not just people
with a
weight problem but
people with diabetes, people with a disease of carbohydrate
intolerance. People
with diabetes were encouraged and are still encouraged to believe that
carbohydrates were a necessary part of life. Most nutritionists and an
unknown
number of physicians still believe in the low-fat dogma despite the
absolute
contradictory results from all kinds of experiments, large and small,
and
despite the one over-powering fact that sits on top of all this: what
happened
in the thirty or forty years of the epidemic of obesity and diabetes
was a
dramatic increase in the consumption of carbohydrate. Fat consumption,
if
anything went down. In the face of all the contradictory evidence, the
Dietary
Guidelines for Americans, the advice for the population sanctioned by
the US
Department of Agriculture (USDA) states flatly that "healthy diets are
high in
carbohydrates." Diets high in carbohydrate may be healthy if you are
healthy
or, more important, if you think that you have control over your weight
and
associated health problems. But, for most people, it's wrong and many
people
know it's wrong. Many physicians and scientists know it's wrong: they
may not
say it out loud because there is a lot of group-think out there and few
of us
are up to fighting with the group
.

How could they all be
wrong?

The Harvard School of Public Health
is very prestigious. How
could they all be wrong? How could it be as bad as the critics say?
Isn't there
peer review? And what do they have to gain? Won't it all come out in
the end?
It is a tough question to answer but the next section will show you
that it is
bad, very bad, however hard it is to say why. It may be a field that is
hopelessly corrupt intellectually. I have always drawn the analogy to
alchemy.
As an student, I could never understand how alchemy could persist for
as long
as it did. We were taught that alchemy was the quest for transmutation,
the
creation of gold from baser metals or other stuff which, of course, is
not
possible. How could the alchemists have kept going in the face of
failure? Part
of the answer is that there was more to alchemy than transmutation. The
alchemists contributed to pharmacology and metallurgy, for example. The
story
on gold, however, is probably that there were simply people who wanted
to think
that they owned gold. There were also people who were willing to
certify that
the "gold" that people had was genuine even if it was simple
copper-plate.
Finally, there were the makers of gold whose reputation might go up if
they
appeared to create gold even if they themselves knew that they were
only doing
some copper-plating. As long as no one broke into the circle,
everything was
smooth.

In a controversial field, there are
few
researchers with real
neutrality but if you sit on a granting agency study section or you are
the
editor of a journal, you are supposed to have self-awareness and know
when you
are unfairly squelching the opposite point of view. Most of the
establishment
in medical nutrition seems incapable of this behavior. Like the
alchemists, the
editors of the prestigious medical journals, The Journal of the
American
Medical Association and the New England Journal of Medicine, are quite
willing
to certify that researchers with like opinions have produced
confirmation. The
panel at the granting agency is willing to say that peer-reviewed
publication
means that the work (which is consistent with their point of view)
deserves
continue funding and it has proved very difficult to break into the
circle. The
media, in turn, pay attention only to these journals. The next section
examines
in detail some of the alchemists' "gold" in nutrition. The point is
that these
studies are poor and the conclusions are unjustified. On the positive
side, it
is informative to understand why it was done wrong and, therefore, what
it
would have taken to do it right. From the point of view of sociology
and
health, this bad practice should be swept away. This is unlikely to
happen and
it is important for individuals to understand how bad it is.