Most dieters regain their lost weight. Scientists say the
newly discovered appetite-stimulating hormone ghrelin is
what makes this happen.
Jamie Cohen writes in abcnews.com that the hormone, which
is secreted in the stomach, sends messages to the brain that
fluctuate throughout the day, depending on how full the
stomach is. Ghrelin produces hunger by rising shortly before
meals and dropping soon after.
A team at the Veterans Affairs Puget Sound Healthcare
System and the University of Washington compared blood
samples of 13 obese patients, before and after six months on
a low-fat, low-calorie diet, with those of five patients who
had undergone gastric bypass surgery. While dieters lost 17
percent of their body weight, their ghrelin levels rose by 24
percent. In contrast, gastric bypass patients dropped 36
percent of their body weight yet their ghrelin levels were 72
percent lower than the dieters.
Unlike ghrelin levels in the diet group, the hormone levels in
the surgery group did not increase and decrease in relation
to meals. In fact, "ghrelin levels not only failed to rise but
dropped profoundly," says Dr. David Cummings, an
endocrinologist at VA Puget Sound Healthcare System and
the University of Washington in Seattle. The reason is that
bypass surgery shrinks the stomach to only 5 percent of its
original size by rerouting the way food passes through the
digestive system. The tiny new stomach can hold only two
teaspoons of food, which then travels into the small
intestine. It?s the presence of ingested food in the stomach
that activates the ghrelin cells there. The permanent absence
of food in the stomach eventually suppresses ghrelin
production.
After a diet-induced weight loss, researchers observed a rise
in blood-ghrelin levels. In addition to increasing food intake,
they discovered that the hormone also slows down the
body's metabolic rate. It?s as if Ghrelin wants us to get back
to our former weight, even if we were dangerously heavy.
Ghrelin is part of the body's built-in defense mechanism to
protect against starvation. Over the course of evolution,
natural selection developed genes that in plentiful times put
weight on our bodies in order to prepare for times of famine.
During famines, our metabolism decreased in order to keep
weight on our bodies, says Cummings. Although our lives
have changed, our hormones still work the same way they
did in prehistoric times.
This is why "weight loss occurs fast at first but then slows as
the body fights vigorously to regain this predetermined set
point," says Dr. Michael Meguid, editor-in-chief of Nutrition
magazine and director of surgical research at the State
University of New York's Upstate Medical University in
Syracuse, N.Y.
Ghrelin triggers hunger, says Frank Chae, assistant professor
surgery and head of obesity surgery at the University of
Colorado Health and Sciences Center in Denver, and "Hunger
is the chief reason for which most dieters quit dieting and
regain the excess weight."
So is the only way to lose weight to have our stomachs
stapled? Not so?researchers believe they can use ghrelin to
help ordinary dieters lose weight and keep it off. One
possibility is the development of a drug that, like gastric
bypass surgery, blocks the production of ghrelin. You can be
sure that drug manufacturers are rushing to develop it right
now.
To learn more,
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Scientists at the U.S. Department of Energy's Brookhaven
National Laboratory have discovered that the sight of food
causes the brain to react with pleasure. This looks very
different from the way the brain lights up when people
actually eat. "This shows us why all the advertisements
about food are so powerful and why we are having problems
with obesity in this country--because we are constantly
being bombarded with food stimuli," says Dr. Nora Volkow,
the psychiatrist who led the study.
If people are aware of what?s going on they may be able to
consciously to block the effects of advertising, the smell of
bread in the supermarket and other stimuli that make people
want to eat when they know they shouldn?t.
Volkow and her colleagues used positron emission
tomography (PET) brain scans to measure dopamine levels in
10 hungry volunteers. Dopamine is a chemical associated in
the brain with pleasure. "They were all of normal weight,"
Volkow says. "We asked them what their favorite foods were.
Then first we studied them under a condition where there
was no stimulation of food --we just asked them to please
tell us about their family genealogy." While this was going
on, each volunteer underwent a PET scan. This gave the
researchers a baseline measurement.
"Then we exposed them to the food they said they liked. But
we told them they wouldn't be able to eat it," Volkow
says. "We were being a little mean for the good of science."
Dopamine levels shot up, which Volkow says is normal.
"It is obviously a mechanism by which nature ensures that
we actually consume food when food is available," she
says. "We never know when food is going to be available.
Well, now we do because we have (convenience stores). But
when we were evolving we didn't, and when there was food
accessible you had to eat it. Unfortunately, we really have
created a system where we are flooded with information
about food.?
Trying to make their results easier to measure, they gave
their volunteers Ritalin (methylphenidate), which is given to
children with attention deficit hyperactivity disorder. It can
amplify the effects of dopamine in the brain, and it increased
the responses of the volunteers to food. "Methylphenidate is
known to take away your appetite," she says. "It's a problem
because children don't want to eat while on
methylphenidate."
So why did it increase the response of people who were
shown images of food? Volkow thinks methylphenidate
actually increases appetite, but only when food is presented
under unusual circumstances. She says, "So if you want your
child to eat while on Ritalin, try to give him the food in non-
regular way. Don't sit him down but present him with food
that he is not expecting to have and then entice him to eat.
Give him a novelty."
To learn more,
click here.
We're spending about $222 billion on dining out each year,
and the Center for Science in the Public Interest says this is
becoming a dangerous habit. The non-profit group makes
some surprising claims about the nutritional value of typical
restaurant dishes.
"More than half of Americans are overweight and it's no
coincidence that we are eating out in record numbers,"
CSPI?s Jayne Hurley says. "More restaurants are serving
huge portions of high-calorie food. An entree or appetizer or
dessert that is less than 1,000 calories is tough to find.
That's half of what you need for the whole day."
CSPI nutritionists spent nine years and several hundred
thousand dollars analyzing about 250 menu items. They
examined national chains like Bennigan's and Applebee's, as
well as family-style, Chinese, Italian, Mexican, Greek,
seafood, steakhouses, pizzerias and some fast food
restaurants. They also looked at mall food, drinks and movie
snacks.
The average person needs about 2,000 to 2,500 calories a
day, containing about 65 grams of fat.
One of their most disturbing discoveries about restaurant
food was the huge amount of calories and fat in appetizers,
Hurley says. Some appetizers contain over 3,000 calories. An
appetizer of deep-fried onions, for instance, has 2,000
calories. Buffalo wings have 1,000 calories.
A plate of cheese fries from the Outback Steakhouse chain
was the worst, with over 3,000 calories and 217 grams of
fat, including 90 grams of saturated fat. This one appetizer
contains the maximum amount of saturated fat that a person
should eat in four days. "It's like starting your meal off with
two T-bone steak dinners with Caesar salad and baked
potatoes and butter, for one person," Hurley says.
If you are going to eat pizza, the wisest thing to do
nutritionally is to stick to one slice of regular cheese pizza,
which contains half the day's supply of saturated fat. "It's
not the crust ? it's the cheese," Hurley says. "And when you
go to the extra cheese and the toppings you have a big
problem."
The Pizza Hut Big New Yorker Sausage pizza contains 570
calories per slice, along with 33 grams of fat and 14 grams of
saturated fat. That amounts to three-quarters of a whole
day's suggested caloric requirements. In terms of health
value, the pizza slice is worse than a Big Mac from
McDonald's. But while most people wouldn't eat more than
one Big Mac, almost everyone has more than one slice of
pizza. Hurley suggests that pizza lovers order half cheese,
and choose vegetable toppings, which cut down on calories
and fats. They should also avoid stuffed crusts.
At Starbucks, a Venti White Chocolate Mocha with whipped
cream contains 600 calories, 25 grams of fat and 15 grams
of saturated fat. That is the equivalent of a Quarter Pounder
with Cheese from McDonald's. If you add a scone, that extra
snack adds 530 calories, 26 grams of fat and 16 grams of
saturated fat. That is the equivalent of a Quarter Pounder.
You can easily reduce the calories by asking for skim milk
and skipping the whipped cream. A latte with skim milk is
only 150 calories and a cappuccino with skim milk is only
100 calories.
A tuna salad sandwich might seem like a healthy choice, but
the tuna is usually drowned in mayonnaise, and that is
where the problem is. An average tuna sandwich has about
830 calories, 56 grams of fat and 10 grams of saturated fat.
If you add potato chips, that equals 1,000 calories. At
Subway, a light mayo version of the tuna salad sandwich is
about one half of the calories.
A chicken Caesar salad may sound healthy, but it isn?t. A
typical one contains 660 calories, 46 grams of fat and 11
grams of saturated fat. Most of the fat is in the salad
dressing, because restaurants put too much on. Try ordering
the dressing on the side, or asking for less of it.
Hurley says restaurants should have to put nutritional values
on their menus. The big chains already have that
information, and they should give it to consumers, so that
they know how what they?re eating.
To learn more,
click here.
Household chores are included in the 30 minutes per day of
moderate physical activity recommended by the U.S.
government as part of a healthy lifestyle, but researchers in
England say there is no evidence that it has any health
benefits. Shah Ebrahim and colleagues at University of
Bristol recruited 2341 women between the ages of 60 and 79
from 15 British towns to fill in questionnaires about their
activity levels. The team also gathered information on the
women's weights, medical history, and heart and lung
function.
Housework turned out to make a huge contribution to
whether or not most women met the U.S. health guidelines.
More than two-thirds of the women were considered healthily
active if housework was included, but 4 in 5 were not
sufficiently active if it was removed.
Regular physical activity such as brisk walking and cycling
significantly reduced average weight, pulse rate and fitness.
But people who spent two and a half hours a week on
housework scored the same on a series of health measures
as those who did no exercise at all. "Housework doesn't
seem to count", says Shah. "I would strongly recommend
that women share the housework with their partner and use
the time afforded to do some more interesting and beneficial
activity."
For more information, click here.
