我們為什么會發胖？
[ 2007-04-25 11:41 ]
人為什么會發胖？比較常見的說法是我們攝入的脂肪高于消耗掉的脂肪，所以就發胖了。但是一項新的研究似乎找到了更科學的原因。想要減肥的人們要注意看啦！
 The discovery of the obesity gene in humans half a
decade ago offered evidence that chronic weight gain is 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. Some researchers in universities 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. 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 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,
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 area 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.
converts to: 轉換為
muck up: 擾亂
crave: 渴望
（來源：英語閱讀網 實習生江?。?/P> |
