Good Calories, Good Science

or Bad Calories, Bad Science?

by Barry Rein

There is little doubt that the United States,
along with much of the rest of the world, is in the midst of an epidemic of
obesity. As we get fatter, the diseases associated with obesity — diabetes,
cardiovascular diseases, cancer — continue to rise. Despite the fact that we
are constantly exhorted to eat less and exercise more, we continue to get
fatter. A neutral observer might conclude that there is something wrong with
the science here. Gary Taubes claims to be one such observer, and he’s
convinced that there is definitely something wrong with the science of
nutrition as it is being practiced today.

The
central thesis of Taubes’ new book, Why
We Get Fat is that carbohydrates in our diet is the cause of this
epidemic. While his thesis is unquestionably controversial, Taubes builds a
strong scientific case that this is indeed what is happening. If he is right —
and his work has the ring of scientific truth about it — it means that much of
the dietary advice we have been following is flat-out wrong.

This book
reviews much of the same ground that his previous work, Good Calories, Bad Calories covered. That
work was nearly five hundred pages of densely-written, heavily annotated
scientific prose. Unsurprisingly, many readers found it to be hard going as it
was aimed at a scientifically-oriented audience. One of Taubes’ aims in Why We Get Fat is to cover
the same ground but, as he says in the introduction, in a form that husbands,
wives, parents, or friends and siblings can read without difficulty.

Gary
Taubes is no neophyte in writing about scientific controversies. Before he
turned his attention to dietary science, Taubes wrote about physics, such as
the highly acclaimed Bad Science: The Short Life and Weird Times of Cold Fusion,
about Pons, Fleischman, and the problems that ensue from announcing a major
scientific discovery by press conference before anyone has a chance to
replicate your findings; and also Nobel Dreams, a critical look at Carlo
Rubbia and the harm to science in general and to a scientific career in
particular that can result from the pursuit of the Nobel Prize. For such work
Taubes won the Science in Society Award of the National Association of Science
Writers three times. He is currently a Robert Wood Johnson Foundation
Investigator in Health Policy Research at the University of California,
Berkeley School of Public Health. So Taubes’ bona fides as a researcher and
writer are impeccable. But is his science?

Why
We Get Fat
is divided into two major sections. The first, Biology, not Physics, is generally a debunking
section that endeavors to break down much of what we think we know about
getting fat. Among other themes, it explains why the calories-in/calories-out
hypothesis is false. The second section, Adiposity
101, clarifies the science behind fat accumulation, and comes up
with some startling, but well-supported conclusions as to why we’re really
getting fat.

Book I
covers a theme that should be familiar to skeptics: that should draw our
conclusions from the evidence, wherever the evidence might lead — in this case,
why we get fat. If the evidence contradicts our beliefs, do we ignore the
evidence, or do we change our beliefs? Taubes wants us to change our beliefs.

The
conventional wisdom describing the obesity epidemic is that we eat too much and
don’t exercise enough. We live in a “toxic environment” where food is too
readily available and where we don’t move around enough to burn off what we
eat. Too much food too easily available, sedentary lifestyles — that’s what’s
making us fat.

Not
quite, says Taubes, beginning with the fact that obesity correlates more
closely with poverty than prosperity. He gives examples of several obese populations
that had no access to any of the factors that we assume are making us fat
today. For example, the Native American tribe known as the Pimas were remarked
upon by mid-19th century explorers as being lean and in fine health. By 1900,
however, the Pima had been consigned to reservations, living on government
rations that consisted largely of white flour and sugar. And, according to the
anthropologists who documented their fate, they were fat.

The Pima
are just one example of several populations that Taubes references who became
fat despite (or because of?) poverty, and despite the absence of the several
factors we assume are making us fat today.

Next,
Taubes goes into the “Elusive Benefits of Undereating,” and “The Elusive
Benefits of Exercise.” Eating less may work in theory, but as Taubes shows,
many medical studies show that it doesn’t work in practice. Calorie starved
patients didn’t lose much weight, and those who did regained it shortly
thereafter. Is this due to the moral weakness of the patients, or is there a
biological reason?

Likewise
exercise: Taubes acknowledges that exercising may well be good for us, but that
it is, generally speaking, not an effective method for losing weight or keeping
it off. In an amusing example, he asks: if you knew you were going to a huge
feast in the evening, what would you do to ensure you had a good appetite?
You’d follow the exact advice we are given to lose weight: eat less and
exercise more. So, the method you would use to make yourself as hungry as
possible for the evening is the same as the advice for losing weight!

For some,
exercise is something we do in a gym, or on a track, or at a sporting venue.
While many of us work in sedentary occupations, domestics, gardeners,
construction workers and other physical laborers get plenty of exercise as a
normal part of their jobs. Taubes points out that, 1) many of the jobs
involving physical activity are done by the poor and disadvantaged and, 2) many
of these people are still fat. So, if physical activity is the key to staying
lean, why do the poor tend to be more obese? This is another argument against
the calories-in/calories-out hypothesis.

One other
example: A 2006 study of 13,000 habitual runners, all subscribers to Runner’s World magazine, found that,
indeed, those who ran the most tended to weigh the least, but that all the
runners tended to get fatter with each passing year. The implication is that in
order to keep weight constant it is necessary to increase running mileage year
after year, as the runner gets progressively older. As Taubes notes, maybe it’s
time to question these underlying beliefs.

There is
a fairly widespread belief that the calories-in/calories-out hypothesis is
supported by the first law of thermodynamics. The first law, also known as the
law of energy conservation, roughly states that energy cannot be created nor
destroyed, but only changed from one form to another. In a section entitled Thermodynamics for Dummies,
Taubes neatly explains why this law does not explain weight gain and loss any
more than Newton’s laws of motion or Einstein’s laws of relativity would. While
it is true that in order to gain weight we must eat more calories than we
expend, the first law explains nothing about causality: it does not explain why we overeat. This is the
real question that must be answered in order to deal with the obesity epidemic,
and it is dealt with in Book II.

Finishing
up Book I, Taubes attempts to take some of the blame away from the obese
themselves. This may not be a popular viewpoint, but if the cause of obesity is
biological (genes and physiology) and not moral (gluttony and sloth), then we have
been barking up the wrong tree when looking for causes and cures. Why, he asks,
would someone voluntarily subject themselves to the opprobrium, and the
debilitating effects, of obesity?

Having
dispensed with many weighty misconceptions, in Book II Taubes goes into what he
argues is the real science of fat. He discusses the role of insulin and insulin
resistance in fat regulation, why some people get fat and not others, and
individual variations in the way fat is regulated. Little of the science Taubes
discusses here is controversial: The operation of insulin, for example, has
been established for decades. What Taubes does, however, is to gather and
synthesize the known science into a coherent whole. This does not mean his
conclusions are not controversial, just that the science itself isn’t.

For
example, in a chapter entitled A
Primer on the Regulation of Fat, Taubes reviews the details of the
science behind fat metabolism, explaining the processes by which fat is
regulated, stored, and released. Basically, when insulin increases fat is
stored; when insulin decreases, fat is released. If we keep our insulin levels
low, fat will be burned. There is more to it than this, which Taubes explains
clearly, but that is the basic idea. There might be a lot less confusion about
weight loss and gain, Taubes insists, if facts like these were more widely
understood.

Taubes
discusses what we can do about the dietary fix we’ve eaten ourselves into. If
you haven’t guessed yet, he considers the culprits to be carbohydrates in all
their forms: “In a world without carbohydrate-rich diets, obesity would be a
rare condition.”

We all
know people who can eat as much as they like yet remain slender. Subsequent
chapters explain why some of us get fat and others stay lean eating
approximately the same amount of food. There is seemingly no justice here! Also
covered is why many of us get heavier as we age. Hint: Taubes reckons it has to
do with insulin resistance.

Taubes
considers fructose to be a serious contributor to being overweight. He quotes
biochemists who called it the most “lipogenic” of carbohydrates, the one
converted most easily to fat. Many of us are aware of, and try to avoid, the
high-fructose corn syrup in sodas and other products. But what about the
fructose in fruits? The fruits we eat have undergone hundreds of years of
selective breeding to increase their size and sweetness. Many contain
substantial amounts of fructose, so Taubes suggests that maybe we should track
the amount of sugar we get when we consume fruit, as well as our sodas.

There is
a lot more controversy in the remainder of the book. Without reviewing all the
details here, Taubes shows how many human cultures in the past obtained most of
their calories from animal foods without suffering from heart disease or any of
the other diseases that plague Western civilization.

Some
other subjects covered that are likely to induce cognitive dissonance in
readers accustomed to the party line on obesity:

• Saturated fat is either
  harmless or beneficial, and is not responsible for heart disease.
• Eating fat is not the cause of
  getting fat.
• Why there is little genuine
  scientific support for the benefits of a low-fat diet.
• A low carbohydrate diet is the
  best diet for humans.

To be
sure, much of what Taubes says is going to be a hard sell. It is diametrically
opposed to the dietary advice outlined by such organizations as the American
Heart Association. Nevertheless, throughout the book Taubes clearly supports
his positions in a way that leaves little room for argument (which is not to
say there won’t be any).

Diet and
nutrition is not a field that has received much scrutiny by the skeptical
community, but Why We Get Fat
fits squarely within the canon of skeptical analysis. We skeptics like to
believe that we reach our conclusions based on reason and evidence, and we are
supposed to be willing to change our opinions in the face of new evidence.
Well, here it is: a book that turns upside-down almost everything we think we
know about human nutrition.

If Taubes
is wrong, well, his error is a doozy! Following his advice will lead to
increases in obesity, cancer, heart disease, diabetes and all the other
conditions Western civilization is heir to. Ironically, this is exactly what we
are already experiencing. If bad science leads to bad results, then maybe it’s
time for a paradigm shift. That is certainly what Taubes believes.