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The Atkins diet, which restricts carbohydrate
intake and prescribes high protein intake in order to lose
weight, was developed by Robert Atkins about 20 years ago.
He was a cardiologist who believed that a high protein diet
would facilitate weight loss and improve serum cholesterol
and thus reduce the incidence of heart disease and other complications
associated with excess body weight.
Atkins (1992) believed that his diet works because
it limits production and excretion of insulin, an anabolic
hormone, which does not promote fat oxidation when elevated,
whereas the lack of insulin leads to mobilization of body
fat for production of energy, as evidenced by the increased
production of ketone bodies. He argued that the increased
production of ketone bodies also reduces appetite, which allows
for better weight maintenance. Although he never conducted
a scientific study to prove that his diet works and is safe,
he used his patient cases in his bestselling book, Dr. Atkins'
New Diet Revolution, as evidence that his diet works. So,
does the diet work as claimed?
Bravata, et al. (2003) attempted to answer this
question by conducting a meta-analysis study. In this study,
the authors examined 107 studies published from 1966 through
2003 that dealt with low carbohydrate (20-60 grams per day)
and high carbohydrate (greater than 60 grams per day) caloric
restricted diets. The majority of the studies had a randomized
research design with a control group. The dietary variables
included the grams of carbohydrate, fat and protein and total
calories that were given to participants per day. Another
variable was the duration of dietary intervention or the number
of days (4-90 days) which the participants received the intervention.
The participants' variables were age, sex, BMI, serum lipid
levels and glycemic control such as blood glucose and insulin
level. The participants were divided in two groups, with one
group receiving a low carbohydrate, high protein diet and
the other group receiving a caloric restricted, high carbohydrate
diet.
The conclusion of this study indicated that the
higher weight loss was achieved by the participants who had
a lower caloric intake and were on the diet for a longer period
of time, but there was no correlation with reduced amounts
of carbohydrate intake. Furthermore, the authors found that
low-carbohydrate diets did not have any adverse effects on
fasting serum lipids, glycemic index or blood pressure. The
authors then concluded that they could not draw any conclusions
for or against low carbohydrate diets.
Brehm, Seely, Daniels, & D'alessio (2003)
conducted another study, titled "A randomized trial comparing
a very low carbohydrate diet and a caloric restricted low
fat diet on body weight and cardiovascular risk factors in
healthy women." For this study, 43 obese females were randomly
assigned to either a carbohydrate restricted diet or a caloric
restricted low fat diet in which the total calories for both
groups were comparable. Body composition, blood pressure,
and fasting blood glucose were measured at baseline, at three
months, and at the end of the study at six months. Each subject
was also given an electrocardiogram during each of these three
test intervals.
The results clearly indicated that the subjects
on the low carbohydrate diet lost more weight (8.5 lbs) and
body fat than the subjects on the restricted low fat diet
(4.8 lbs). The other measurements were within the normal range
at the baseline, however, the lab data showed improvement
at the three-month interval and the six-month end of study
interval. The authors of this study concluded that the low-carbohydrate
diet is more effective in promoting weight loss than the low-fat
diet for a short period of time. They also concluded that
the low-carbohydrate diet does not have adverse effects on
the cardiovascular system in healthy women.
So, this last study indicated that the low-carbohydrate
diet can be more effective in initial weight loss and both
of the studies indicated that a low-carbohydrate diet does
not have any adverse effects on health during a short period
of time. Of course, neither of these studies discusses the
side effects of low fiber with this kind of diet. Fiber, which
is the nondigestible part of complex carbohydrates that is
fermented by the bacteria of colon, is not only necessary
for the healthy function of the gastrointestinal tract; it
has also been linked to the reduced risk of colon cancer (Lieberman,
Prindiville, Weiss, Willett, 2003). The other problem with
this kind of diet is that too much protein can increase excretion
of calcium, and thus, cause bone damage. Reddy, Wang, Sakhaee,
Brinkley & Pack (2002) demonstrated that in human subjects
who received a high protein diet, urinary calcium excretion
level increased from 160 mg /dl to 258 mg/dl, an almost two-fold
increase in calcium losses, which can led to bone demineralization.
High intake of fat has also been associated with increased
risk of some types of cancer, which may not be seen with the
above studies since the study durations were short.
From:
"Fad Diets Analyzed" by Jaleh Dehpahlavan (full citations
are available
on the webpage) http://www.chiro.org/nutrition/FULL/Fad_Diets_Analyzed.html
The FDA published a bulletin detailing its intentions
to classify "low carbohydrate" and "carbohydrate free" terminology.
They also are seeking to define what a "net carbohydrate"
is. See their bulletin at
http://www.fda.gov/oc/initiatives/obesity/factsheet.html
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