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Note 416.0 To Diet or Not to Diet No replies
ICARUS::CFIELD "Corey" 216 lines 9-MAR-1989 13:42
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Thanks, Mike for the article. It makes a lot of sense. I'm happy
now that I am losing only 1 - 1 1/2 lbs. per week with Nutri-System.
The following is the article that Mike was talking about in Note
415.0
DEATH-DEFYING DIETS
NEW RISKS OF YO-YOING
BY JERE DANIEL
If at first you don't succeed, diet, diet again.
Nowhere is this aphorism put more to the test than in the 50 million
Americans--predominantly women--who devote a good part of their
lives to repeated, usually futile, attempts to shed unwanted pounds.
About 95 percent of the patients who check into the noted St. Luke's
Hospital Nutrition Clinic in New York City are failed repeat dieters.
Thirty-one percent of American women surveyed in a Gallup poll said
they diet at least once a month. And in a national magazine survey
of 15,000 overweight readers, 42 percent confessed they were
"on-again, off-again" dieters.
Make that read "off-again" dieters.
More than half of all dieters ultimately gain back more weight than
they lose, estimates Dr. C. Wayne Callaway, associate professor
of medicine at George Washington University School of Medicine and
former acting director of the National Academy of Sciences Food
and Nutrition Board. The unfortunate truth is that the harder and
more often most people try to take weight off, the more likely they
are to bounce back to their former weight--and higher. They are
victims of a phenomenon causing increasing concern to obesity
authorities: the yo-yo effect.
It's bad enough that yo-yo- dieting is frustrating and destructive
to self-esteem. But its harmful effects are physical as well as
psychological. It increases the risk of high blood pressure and
heart disease; throws the body's metabolism out of whack; and
negatively affects the distribution of body fat. Also, the more
often weight rebound occurs, the more profound the effects. What
was begun as a way to prolong life may actually shorten it.
In their efforts to determine what causes yo-yoing and how to prevent
it, medical authorities have made two interesting observations.
o Unless done slowly, the weight-loss process itself may be harmful.
o More effort might be better devoted to urging people to accept
their bodies as they are.
"We have become a nation of yo-yo dieters, our weight constantly
cycling--down, up, down, up--always inching a bit higher than before,"
says Kelly Brownell, Ph.D., of the University of Pennsylvania's
Obesity Research Group. He is directing a national Weight Cycling
Project to probe the intricacies of the yo-yo phenomenon.
A typical yo-yo dieter might be the 40-year-old housewife who started
dieting at 16. She has "tried every diet and pill around." The
pattern is always the same: She loses 30 pounds and bounces back
with 45; tries another diet and loses the 45,then it's up to 55
pounds. Each time it's harder to lose. "I regain more than I lost,"
she says, ruefully regarding her 250-pound body.
"If the miracle diets really worked, surely weight loss wouldn't
be the big business that it is", Dr. Callaway asserts. "Americans
spend around ten billion dollars a year trying to lose weight."
One way yo-yoing can be harmful is that dieting in general disrupts
body metabolism. When people cut calories deliberately, the body's
metabolic rate drops dramatically--as much as 20 percent within
two weeks. The body adapts as it would during a famine, requiring
fewer calories to supply the energy it needs. This is one reason
dieters often stop losing weight after a few weeks.
Unfortunately, the drop in metabolism often persists even after
dieters regain their lost weight--or even if they keep it off.
At Rockefeller University in New York, Dr. Jules Hirsch and colleagues
studied grossly obese people who lost an average of 124 pounds each.
They required significantly fewer calories to maintain their new
weight--just 2,171 calories per day, less than the 2,280 calories
normal weight people need to fuel their bodies daily.
"We think yo-yo cycling disturbs the body's metabolism even more,
making weight loss progressively more difficult," Dr. Brownell says.
Studies seem to bear this out. Rats he put on an enforced diet
took 21 days to go from obese to normal and 46 days to regain their
former weight after they stopped dieting. On a second try, the
same rats took 46 days to lose the same poundage--and only 14 days
to regain it. A Swedish study found that after only one yo-yo cycle,
obese rats were five times more food-efficient than normal rats;
they could maintain their functions on only one-fifth the calories
they previously needed.
Pioneer researcher Dr. George Blackburn, associate professor of
surgery at the Harvard Medical School, found that patients who went
through his clinic's rigidly controlled weight-loss program twice
in nine years lost much less weight the second time--5.7 pounds
per week versus 7.25 pounds the first time.
Dieting, especially crash dieting, subjects the body to a constellation
of hormonal and physiological changes. These changes may initially
help to take weight off and reduce high blood pressure. But sometimes
these effects give way to harmful ones as the body tries to make
do with fewer calories. Dieting sets off many biochemical changes
to accomplish this. "Yo-yo dieting," says Dr. Callaway, "kicks
in these changes more quickly and may make their harmful effects
more profound." Among the upheavals:
NOREPINEPHRINE. Overeating increases the level of norepinephrine,
an adrenal gland hormone that constricts blood vessels--meaning
it helps raise blood pressure. Normally, during starvation (and
dieting is voluntary starvation), the brain produces less
norepinephrine. Initially, blood pressure falls. But according
to Paul Ernsberger, Ph.D, assistant professor of neurobiology at
Cornell University Medical School, yo-yoing ultimately makes the
norepinephrine-producing nerve cells permanently overactive; as
a result, his work with rats shows, blood pressure no longer drops
as animals go through the down side of weight swings.
INSULIN. Levels of this hormone, which controls carbohydrate
metabolism, drop during weight loss. Fat and muscle cells become
more insulin sensitive and burn more fat; weight falls. However,
when the weight is regained, insulin levels rise and may set off
an increased production of norepinphrine.
LIPOPROTEIN LIPASE. An enzyme called lipoprotein lipase governs
how much fat a body stores in its fat cells. In response to
starvation, it signals cells to store more--exactly what the dieter
doesn't want. Thus, a woman who has lost weight gains more fat from
an ice cream sundae than does her thin friend.
What impact do these changes have on you?
o Yo-yo and crash dieting may cause weight lost from lean muscle
tissue (even the heart) to be regained as fat.
o Regained fat tends to come back more in the belly than in the
butt. Abdominal fat may be easier to lose than fat on the hips
or legs--but it raises the risk of heart disease.
o Yo-yo dieting appears to increase the appetite for fatty foods.
Given a choice of carbohydrates, protein, or fatty food, rats
invariably select more fat after dieting. The phenomenon seems
to hold true in humans as well.
What specific health risks does yo-yo dieting pose? Dr. Callaway,
for one, says the more often body fat is lost and then regained
as abdominal fat, the greater the possibility of developing diabetes
and of augmenting factors that contribute to heart failure:
hypertension and higher cholesterol levels. Some evidence even
shows that yo-yoing adds to the risk of endometrial cancer in women,
though the link is unclear.
In a Northwestern University study, observes Dr. Brownell, the highest
risk of sudden death from coronaries was among men with the greatest
up-and-down weight swings. In the famous 40-year-long Framingham
heart study, people who lost only ten percent of their body weight
lessened their heart disease risk by 20 percent. But those who
regained that ten percent increased their risk of heart disease
by 30 percent.
Dr. Ernsberger cites an even more dramatic study of obese men conducted
by the West Los Angeles Veteran's Administration Medical Center.
After losing and regaining repeatedly, 80 percent ultimately developed
diabetes and 25 percent died of heart disease. Their premature
death rate was up to 13 times higher than equally obese non-dieters
in a Scandinavian study.
Overweight people are twice as likely to develop high blood pressure
than their leaner peers. Doctors have thought that excess poundage
alone caused high blood pressure. Dr. Ernsberger thinks differently.
His studies indicate it's not so much that people are heavy but
that they are dieters. Loss-gain cycles eventually cause "dieters
hypertension," set in motion by the stepped-up norepinephrine
production. He believes it makes yo-yoers especially prone to
congestive heart failure.
If weight remains constant--high or low--dieters hypertension goes
away after about two years. But recovery is harder with each yo-yo
cycle. And since fat cells fill up with more fat after each dieting
bout, subsequent dieting is tougher.
Given the frustrations and the risks of yo-yo dieting, what's an
overweight person to do?
The medical consensus is still that if you're 20 percent or more
above your proper weight, you should trim down. But, as Dr. Callaway
puts it bluntly, "Don't go on stupid starvation or fad diets," or
crash exercise programs. Combining exercise with a very low-calorie
diet can trigger dangerously low metabolic rates. And don't expect
pills or appetite suppressants to take weight off for good.
Second, you need not shed a lot of excess poundage to reduce high
blood pressure, cholesterol or blood sugar. Taking off just ten
percent of excess weight may do it.
Third, take it slow and easy. Losing as little as half a pound
a week may be far more permanent and less risky.
Fourth, don't try to diet unless you're really committed and your
life circumstances will support a long-term effort, Dr. Brownell
urges. If you're under a significant amount of stress--which could
take your energies away from dieting--it may be better to wait.
Fifth, realize that what you eat may be far more important than
how much. Albert Stunkard, M.D., head of the Obesity Research Group
at the University of Pennsylvania, emphasizes that fat contributes
more calories than do carbohydrates or proteins, though it provides
less energy when it burned. Watch the fat, and the calories will
take care of themselves.
Sixth, know that some people may be better off not dieting at all.
As Dr. Callaway puts it, "The woman who weighed 200 pounds at age
18 and now weighs 185 may be healthier than the woman who weighed
120 pounds at 18 and now weighs 150." In the future, he believes,
people should be classified not according to how heavy they are,
but whether they should--and can--lose weight. Dieting may be
self-defeating!
Taken without permission from the magazine "Longevity".
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