There has recently been a
resurgence of diets promoting low carbohydrate intake,
but the scientific evidence supporting the safety and
effectiveness of these diets is limited. This is the
first published scientific study of the popular
low-carbohydrate Atkins diet in two decades, and
research is continuing.
The study appears in the July
2002 issue of the American Journal of Medicine and was
funded by an unrestricted grant from The Dr. Robert C.
Atkins Foundation.
"Study participants were
put on a very low carbohydrate diet of 25 grams per day
for six months," said Eric Westman, M.D., associate
professor of medicine at Duke and principal investigator
of the study. "They could eat an unlimited amount
of meat and eggs, as well as two cups of salad and one
cup of low-carbohydrate vegetables such as broccoli and
cauliflower a day."
Researchers found that 80
percent of the 50 enrolled patients adhered to the diet
program for the duration of the study and lost an
average of 10 percent of their original body weight. The
average amount of weight lost per person was
approximately 20 pounds.
"While we're impressed with
the weight loss of this diet, we still are not sure
about the safety of it," Westman said. "More
studies need to be done in order to be confident about
the long-term safety of this type of diet."
For example, all participants
developed ketonuria, the presence of measurable ketones
in urine. The level seen in this study translates to
roughly that of a non-dieting person if they didn't eat
for a couple of days, said Westman. "This is a
finding that we need to learn more about. The level of
ketones present was not terribly high, but we don't know
if this is safe or harmful to one's health over a long
period of time."
The study further showed that
patients' cholesterol levels improved by the end of six
months—a finding that was unexpected, according to
Westman.
"We were somewhat surprised
to find that patients' blood lipid profiles improved,
even though there was much more fat in the diet,"
he said. "We had thought the fat in the diet would
increase the cholesterol."
Cholesterol is a fat-like
substance that circulates in the blood stream and can
accumulate to the point of blocking blood vessels and
arteries. Having a high level of blood cholesterol is a
major risk factor for heart disease, according to the
National Heart Lung and Blood Institute, part of the
National Institutes of Health. Although exercise was
recommended, it was not a requirement for the study.
Half of the subjects didn't exercise at all and still
lost weight, according to the researchers. Because of
the intensity of this type of diet program, Westman
cautions that "if someone has a medical problem or
is taking medications, they should only do this diet
under the supervision of a health care provider."
Studies suggest Atkins
diet is safe
NEW YORK, Feb 18 (Reuters
Health)
The extremely
carbohydrate-restricted Atkins diet is a safe, effective
way to lose weight, according to studies presented at
the Southern Society of General Internal Medicine in New
Orleans.
A study of the diet conducted at the Durham VA Medical
Center in North Carolina showed that on average, mildly
obese people lost about 21 pounds in four months on the
diet, and had positive changes in heart risk factors
such as reduced cholesterol and increased HDL or
"good cholesterol." These results are
supported by a second study from researchers at the
Atkins Center for Complementary Medicine in New York.
The Durham study included 41 mildly obese, healthy
people who attended an outpatient clinic. The study
participants followed a program that reduced
carbohydrate intake to less than 20 grams per day, and
included vitamin supplements, fish oil supplements and
20 minutes of exercise at least three times per week.
Over four months on the diet, the participants lost an
average of 21.3 pounds, and showed a 6.1% drop in
cholesterol, and almost a 40% drop in the level of
triglycerides in their blood. In addition, their HDL
levels increased by about 7%.
In a press release, the researchers also say that their
study did not find any of the safety concerns voiced by
the American Dietetic Association, such as potentially
dangerous effects on liver and kidney function.
"In four short months on the Atkins Diet, we were
able to confirm scientifically what Dr. Atkins states he
has seen in his practice over the past decades. The diet
lowers cholesterol and triglycerides and raises HDL...
which may represent an entirely new approach to the
control and prevention of heart disease," said lead
researcher Dr. Eric C. Westman, assistant professor of
medicine at North Carolina's Duke University.
The study is continuing in order to assess the long-term
effects of the diet.
Reporting the results of the second study, Colette
Heimowitz, director of nutrition at the Atkins Center in
New York, said that it was based on 319 overweight or
obese patients treated at the Center for at least a
year. Investigators collected information on weight,
blood pressure, cholesterol, kidney and liver function
and other parameters during the study.
"What we found is what we already knew from
anecdotal data," Heimowitz told Reuters Health in
an interview after the meeting on Friday. "There
were some pretty impressive benefits in body
composition, HDL levels went up, LDL levels went down
and blood pressure decreased," she reported. Where
HDL is the good cholesterol for its association with
reduced heart risk, LDL has earned the name of being the
"bad" cholesterol because high levels are
associated with heart disease.
"We now have data for the scientific
community" on the healthful benefits of the Atkins
diet, Heimowitz asserted.
The Atkins diet severely restricts carbohydrate intake
to induce a state of ketosis, or metabolic starvation.
Dieters are encouraged to measure urinary ketone
excretion as an indication of how effective the diet is
in inducing fat breakdown. "Ketosis is a benign
byproduct of fat burning," Heimowitz asserted.
"With an adequate protein and fat intake, there is
no loss of muscle mass...There is no change in (blood)
pH if the diet is properly done," she said.
However the diet is not for everyone, Heimowitz warned.
"It's for those who need a correction in their
sugar and carbohydrate metabolism...We encourage
(vitamin) supplementation and an intake of 'good' fats,
such as fish oil," Heimowitz commented.
