Sugar substitutes may offer sweet treats for calorie-conscious dieters,
but a new study shows that they may also play tricks on the body and
sabotage weight-loss efforts. Researchers say artificial sweeteners may
interfere with the body's natural ability to count calories based on a
food's sweetness and make people prone to overindulging in other sweet
foods and beverages.
For example, drinking a diet
soft drink rather than a sugary one at lunch may reduce the calorie
count of the meal, but it may trick the body into thinking that other
sweet items don't have as many calories either. Researchers say the findings show that losing the ability to judge a
food's calorie content based on its sweetness may be contributing to
the dramatic rise in overweight and obesity rates in the U.S. But don't
ditch your diet drink yet.
"The message is not to give up your diet soda and go drink a regular soda," says researcher Susan Swithers, PhD, associate professor of psychological sciences at
Purdue University. "But when you do drink beverages you probably need to
pay a little more attention to whether they have calories or not and
what the consequences of that fact will be on the rest of your diet."
Sweetness Provides Calorie-Counting Clues
Swithers
says that in the past, a food's sweetness provided valuable clues about
its caloric content, and something sweet was usually a good source
of energy. "Before things like artificial sweeteners, these
relationships would be very reliable," says Swithers. "Animals needed to
find good sources of calories and needed to know whether eating
something provided them with lots of calories." "It's only been
relatively recently that foods have been introduced that violate those
kind of relationships, such as something very sweet that has no
calories," Swithers tells WebMD.
According to researchers, the
number of Americans who consume sugar-free, artificially sweetened
products has grown from less than 70 million in 1987 to more than 160
million in 2000. At the same time that more people are drinking and
eating foods sweetened with low-calorie sweeteners, such as aspartame
and saccharin, they're not getting any thinner. In contrast, more people
are becoming overweight or obese.
That prompted researchers to test
whether not being able to use sensory clues to predict the calorie
content of foods might contribute to overeating and weight gain.
Artificial Sweeteners May Trick the Brain
In the study, published in the July issue of the
International Journal of Obesity,
two groups of rats were fed either a mix of high-calorie,
sugar-sweetened, and low-calorie, artificially sweetened liquids; or
sugar-sweetened liquids alone. This was fed to the rats in
addition their regular diet. After 10 days, they were offered a
high-calorie, chocolate-flavored snack. The study showed that rats fed
the mixed liquids ate more of their regular chow after the sweet snack
than those who had been fed sugar-sweetened liquids alone.
Researchers
say the results show that the experience of drinking artificially
sweetened, low-calorie liquids had damaged the rats' natural ability to
compensate for the calories in the snack.
Manipulating Food Can Derail Diets
Health psychologist Daniel C. Stettner, PhD, says damaging the body's
natural ability to count calories based on food's sweetness is just
one way in which food can be manipulated to change eating habits and
contribute to obesity. "We do more to manipulate food than just add
artificial sweeteners. The food industry plays with the sugar, the fat,
and the salt," Stettner tells WebMD. "It's like a shell game."
Stettner
says that when manufacturers lower the sugar content in foods, they
typically increase the fat or the salt content to compensate for
any change in how it tastes or feels in the mouth. For example,
sugar-free ice
creams can be made higher in fat content. "Sugar-free foods can still be calorie-dense, and that can mess
up weight," says Stettner, who specializes in weight issues at Northpointe Health Center in Berkley, Mich.
Stettner
says the body's natural calorie counter and sense of balance is also
affected by genetics, environment, marketing, and physical activity
level, which were not taken into account by this study. "So many
factors contribute to obesity," says Stettner. Although artificial
sweeteners may alter the eating behavior of rats, he says the
same principle may not necessarily apply to humans.
Susan
Swithers, PhD, adds that many types of learning processes
translate from rats to humans, but she acknowledges that the loss of the
ability to judge the calorie content of sweet foods is probably just
one of the contributors to the rise in overweight and obesity. However,
she says humans also have a distinct advantage over rats when it comes
to controlling how many calories they put into their body.
"Rats
can't read the labels, but we can," says Swithers. "We have to take
that extra step of reading the labels or asking how many calories are in
there. That may be enough so that we can compensate for those sweet
calories."
Source:
http://www.webmd.com/diet/news/20040630/artificial-sweeteners-damage-diet-efforts