In the mid-19th century, William
Banting first popularized the low-carbohydrate weight-loss plan that has once
again grabbed the media's collective attention. Banting was a well-meaning London
undertaker who grew so fat in middle age that he could not descend a staircase
face first, for fear of being toppled by his copious paunch.
His friend and physician, the noted British aural surgeon William Harvey, prescribed
a regimen focused on meat, small amounts of fruit and liberal lashings of Claret,
sherry and madeira, which helped Banting drop 35 pounds in 38 weeks. Delighted
by this result, Banting printed the diet at his own expense and distributed
2,500 free copies. The diet was so popular that when he died in 1878 nearly
60,000 additional copies had been sold at sixpence apiece. "Bantingism"
became synonymous for dieting, "bant" common usage for losing weight,
and Banting a legend.
Banting's plan has resurfaced in many forms over the years, more than a few
of them best sellers. Most recently the Dr. Atkins Diet Revolution—a 30-year-old
scheme—has gotten the buzz. Atkins's claim is that carbohydrates, not
fat, are to blame for the ballooning of Americans. But this theory loses credibility
when one considers that while Atkins's book was selling 10 million copies, obesity
blossomed into a full-blown epidemic.
The discovery of the obesity gene in humans half a decade ago offered evidence
that chronic weight gain is at its heart biological, the consequence of a mismatch
between nature and nurture. Simplistic explanations, such as blaming obesity
on a drop in fat consumption, ignore scientific reality. In countries like India
and China, obesity was virtually unknown until the introduction of a high-fat,
Western-style diet.
One well-known reason for this is that dietary fat converts to body fat more
efficiently than does protein or carbohydrate, but recently scientists have
uncovered what appears to be an equally important factor. Peter Havel, of the
University of California, Davis, and Michael Schwartz, of the University of
Washington, Seattle, are investigating the possibility that high levels of fat
and fructose are mucking up our brain chemistry, and thereby muting the signals
that would normally tell us to put down the fork. These signals are produced
by peptides, which are regulated by a number of hormones, namely insulin, leptin
and ghrenlin. Under normal conditions these hormones help maintain a stable
body weight by adjusting levels of the peptides that control eating. But a diet
loaded with fat and fructose hampers the regulation of these hormones. Complicating
matters still further, Schwartz says, is that the brain loses its ability to
respond to these hormones as body fat increases, so the obese are doubly penalized.
Other researchers are finding evidence that constant exposure to fat and sugar
can cause some humans to crave them as they do an addictive drug. A Princeton
University psychologist recently showed that rats fed a high-sugar diet were,
when the sugar was removed, thrown into a state of anxiety similar to that seen
in withdrawal from morphine or nicotine. Sarah Leibowitz, a neurobiologist at
Rockefeller University, believes that frequent exposure to fatty foods may configure
the brain to crave still more fat. She has shown in animal studies that galanin,
a brain peptide that simulates eating behavior and decreases energy expenditure,
increases when the animal eats a high-fat diet.
There are many factors contributing to the explosion of obesity in the United
States, and the world, but the radical changes in the composition of our diet
are first among them. While scientific work in this arena is in its infancy,
it's already clear that varying the amount of fat and other nutrients in the
diet affects brain chemistry by activating certain genes, and this in turn directs
our dietary preferences. By submitting ourselves to a steady dose of highly
processed, sweet, high-fat foods, we have unwittingly entered into a dangerous
experiment, the long-term consequences of which are only now beginning to surface.
Shell is author of "The Hungry Gene: The Science of Fat and the Future
of Thin," published this by Atlantic Monthly Press.
© 2002 Newsweek, Inc.