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Artificial
Sweeteners Make
Calorie Counting Hard
Using artificial sweeteners may throw
off our ability to monitor how many calories we consume, new animal
research suggests.
Rats that had been fed an artificially
sweetened diet tended to overeat when given naturally sweetened
high-calorie food compared with rats that had never consumed artificial
sweeteners.
Researchers also found that the
thickness of a sweetened drink seems to interfere with rats' abilities
to keep their calorie consumption under control.
The results are preliminary, but
they raise the possibility that artificially sweetened foods and
high-calorie beverages may interfere with the ability to keep
calorie consumption under control, one of the study's authors
stated.
"We propose that humans and other
animals use sweetness and viscosity to help estimate the caloric
content of the foods they eat, with sweeter and thicker foods
signaling more calories and less sweet and thinner foods signaling
fewer calories," said Dr. Terry L. Davidson of Purdue University
in West Lafayette, Indiana.
Along with Purdue co-author Dr.
Susan E. Swithers, Davidson hypothesized that consuming foods
and beverages that are either low-calorie but very sweet or high-calorie
but very thin may interfere with the ability to rely on taste
and thickness to regulate caloric intake.
"The data presented in our paper
suggest that such interference increases the tendency to overeat
and gain weight in rats," Davidson said.
Davidson explained that one way
that people and other animals are thought to control their weight
is by reducing the amount of food they eat on some occasions to
compensate for pigging out at other times.
"I think many people who now struggle
to keep off extra pounds remember a time when they could perform
this type of compensation almost effortlessly, without consciously
trying to watch and control their caloric intake," Davidson said.
The Purdue researcher said he doubts
that there is a single explanation for the diminished ability
to control calories without much conscious reckoning. But it is
possible that certain foods that have become popular in recent
years may play at least some part, he said.
For instance, the number of Americans
who consume sugar-free products has risen from less than 70 million
in 1987 to more than 160 million in 2000, Davidson and Swithers
note in a report in the International Journal of Obesity. Consumption
of high-calorie soft drinks has also surged during the past few
decades.
The researchers conducted two rat
studies to evaluate the impact of artificial sweeteners and high-calorie
drinks on calorie consumption.
In the first, one group of rats
was fed a naturally sweetened liquid while another group was given
an artificially sweetened liquid. After consuming the sweet drink
for more than a week, the rats were offered a high-calorie, sweet
chocolate treat before having a meal of normal rat chow.
Rats that were used to drinking
the naturally sweetened liquid compensated for the pre-meal snack
by eating less rat chow. But the rats accustomed to the artificially
sweetened liquid ate more rat chow, suggesting that they were
less adept at figuring out how many calories they should eat.
In the second study, rats were
given a high-calorie dietary supplement that had the consistency
of either chocolate milk or chocolate pudding. Even though the
thick and thin supplements had the same amount of calories, rats
given the thin one consumed more and gained more weight during
the study.
"Our preliminary research indicates
that the effects of consuming certain types of processed foods
on longer-term caloric intake and body weight deserve additional
study," Davidson said. Future studies should try to determine
to what extent people normally use taste and viscosity to gauge
calories, he said.
SOURCE: International Journal of
Obesity, July 2004.
Reference
Source 89
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