It’s
a grim fact that only a minority of Americans―one adult in
three—enjoys a normal weight.
It’s
not as if the majority of us aren’t trying to slim down. We spent
an estimated $40
billion on
diet-related products in 2009, yet the only thing we thinned was our
wallets.
So
if fad diets, weight-loss products and the latest exercise craze
aren’t the solution, can researchers help us find the answer?
Responding
to the urgent need for a remedy, scientists are exploring the
chemistry and mechanisms of weight gain. Their research begins with
an effort to answer key questions. For example, since so many of us
are overweight, is it possible that certain foods are addictive? Are
we programmed to overeat?
The
notion that certain foods, like narcotics, are addictive and that
this addiction explains the compulsion to overeat is gaining
traction. Recent findings based on research with rats reported in
Science
News
(November 21, 2009)
provide support for this idea.
Rats
fed a diet rich in junk food (processed cakes, sausage, bacon,
cheesecake, etc.) quickly adopted the habits of drug addicts. They
wanted more and more junk food and needed more and more to feel
satisfied; they refused to eat regular food once they were hooked on
the rich, sweet food, even if rejecting normal food meant starving;
they continued to eat junk food even when consuming it triggered an
electric shock to their feet; and once they went back to nutritious
rat chow, their bodies took a long time to recover. In fact, some
never did return to normal eating habits.
Tests
on the rats’ brains and intestines during and after the rats
consumed junk food showed biochemical changes. Researchers concluded
that the rats’ brains and digestive systems had become captive of
the chemical changes resulting from eating junk food—the very
definition of addiction. And like drug addiction, junk food addiction
can produce changes that are difficult to unwire.
If
the experiment with rats is predictive of human behavior, then the
chemical changes in the rats’ bodies and the rats’ addictive
habits could explain the growing problem of obesity in the United
States. As we consume more and more rich, sugary food, we want more
and more, and we gain more and more weight.
That
brings us to the next question: If overeating is inevitable, can we
somehow avoid storing the surplus calories as fat?
Breakthroughs
is a publication of the UC Berkeley College of Natural Resources
featuring scientific advances with far-reaching implications. The
lead article in the fall 2009 issue, titled “Burn,
Baby, Burn:
Key Enzyme Tunes Fat Metabolism,” explains the findings of Hei Sook
Sul, professor of nutritional sciences and toxicology, a scientist
with a lifelong passion for understanding metabolism.
When
explaining the mechanism of obesity, Dr. Sul’s research on one
particular enzyme confirms what we all have observed: that some of us
can eat whatever we want and stay lean while others of us eat very
little and gain weight.
Dr.
Sul, the principal investigator on the research team, reports, “We
have discovered a new enzyme within fat cells that is a key regulator
of fat metabolism and body weight, making it a promising target in
the search for a treatment of human obesity.”
In
their experiments, the investigators gave two groups of mice an
appetizing buffet of tasty, high-fat mouse food. One group had the
gene that expressed the enzyme; the other group did not. The presence
of the enzyme did not affect appetite: both groups ate the same
amount of food. But as the mice grew older, the group without the
enzyme gained weight while the other group stayed lean.
For
more on “Fat Mouse, Skinny Mouse,” go here.
If
Dr. Sul and her investigators could work with drug companies to
patent and
market an inhibitor of this enzyme in a pill that
I and others could take without side effects, we could eat whatever
we wanted without fear of gaining weight.
My
first question to Dr. Sul was, “How long will it be before this or
an equivalent enzyme is available in prescription form?” Her answer
was more prudent than I would have preferred: “We are far down the
road from translating research on this enzyme in mice into an
application for humans for the management of obesity. What works with
mice doesn’t always work with humans.” Dr. Sul added that
researchers across the nation are exploring different approaches to
understanding the chemistry of obesity, and her research is only one
piece of this larger effort.
My
second question involved the difference between the metabolism rates
of the mice that stayed lean compared to those that gained weight.
Here, Dr. Sul’s insight was more hopeful: “The range is tiny.”
But, she explained, the results are cumulative. Over time, even a
small amount of excess calorie consumption will eventually result in
excess fat. Conversely, because the range is tiny, we can
underconsume a small amount each day and trigger a cumulative weight
loss.
The
dialogue with Dr. Sul was enlightening, even though her answers were
not what I might have hoped for. Given her brilliant background as a
leading researcher in metabolism, I shouldn’t be surprised that she
confirmed the hard truth: there are no magic pills when it comes to
fitness and weight loss—at least not yet.
I
am, however, reassured that she and other researchers are exploring
the mysteries of metabolism and obesity. Their efforts reminded me of
a passage from T. S. Eliot that was quoted by another scientist to
explain his passion for research:
We
shall not cease from exploration
And
the end of all our exploring
Will
be to arrive where we started
And
know the place for the first time.
For
those of us pursuing fitness and trying to maintain a reasonable
weight, the place where we started and now return to (at least for
the foreseeable future) is the same: exercise regularly and eat
healthfully.
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