From: Harvey Newstrom (mail@HarveyNewstrom.com)
Date: Thu May 22 2003 - 21:55:00 MDT
gts wrote,
> Atkins Diet Shows Surprising Results, Researcher Says; One-year
> Study Shows
> Diet May Be As Effective And Safe As Conventional Diets
> http://www.sciencedaily.com/releases/2003/05/030522083022.htm
Here is an abstract of the study itself:
<http://content.nejm.org/cgi/content/short/348/21/2082>
This study looked very interesting. It confirmed one of my complaints,
which was that no previous scientifically-controlled studies have been
performed on the Atkins diet. This is the very first one. I was very eager
to see the results of this, since it claims to be the first and only
controlled study to be performed on the Atkins diet.
I purchased this article for review. It was not as interesting as the
abstract or media hype made it appear.
In summary:
It is not a very good study because they didn't make sure people followed
the diets. The study admits a lot of adherence and attrition problems.
There were some results at first at the three-month point, but these
disappeared by the end of the year-long study. This was when compliance was
at its worst. The main claim of the study is that Atkins was no different
than conventional diets at the end, but it's not clear that anybody was
following Atkins by then. I think the earlier results are more conclusive,
and they did not fare well for the Atkins diet.
Details:
They did not control the foods eaten by people. People were supposed to
follow the diets assigned to them, but there were a lot of adherence and
attrition problems. It is not clear how much the people followed the diets.
Many of the measurements, including keytones, cholesterol, weight loss,
etc., had changes at the three month point, but went away at six months and
twelve months. It seems that the participants were not following the diets
as well later in the year. This means that the final results may not be as
accurate as the first few months. The study itself concluded that more
studies need to be done to determine the safety or efficacy of the Atkins
diet. It does not support or vindicate the Atkins diet, despite the media
hype.
They seemed to refute the basic keytone theory of the Atkins diet. They
noted that there was no correlation between the excretion of keytones and
weight loss. Again, the weight loss seemed directly proportional to the
number of calories consumed. Keytosis did not seem to speed up or assist
the process. They also noted that ketosis was not present after six months.
Either the keytosis stopped working, or the participants were no longer
following the diet at that point.
They seem to refute that macronutrient ratios had any effect. The weight
loss in the beginning of the Atkins diet was due to the consumption of less
total calories. They concluded that "When the energy content of an
energy-deficit diet is stable, macronutrient composition does not influence
weight loss." It appears that equal calories produce equal weight loss no
matter what the macronutrient combination is. This seems to refute the idea
that different calories contribute to weight gain differently. It supports
the idea that reducing total calories is equally effective for weight loss
on high-carb, low-carb, high-fat, low-fat, high-protein, or low-protein
diets.
There seemed to be little difference between diet results. It appears that
most of the blood measurements showed no difference between the two diet
groups. There was no difference in weight loss, blood pressure, insulin
sensitivity or total cholesterol between the groups. There were some
difference in the beginning, which I think are more significant due to the
latter attrition rates, but these do not look good for the Atkins diet.
For total cholesterol, the conventional diet dropped it, while the Atkins
diet increased it. The difference between the groups lessened toward the
end of the year.
For LDL (bad) cholesterol, the conventional diet dropped it while the Atkins
diet increased it. The difference between the groups lessened toward the
end of the year.
For HDL (good cholesterol), both diets increased it, while the Atkins
increased it at a higher rate.
For triglycerides, both diets decreased it. For some reason, the
conventional diet reversed direction and went back up toward the end of the
year.
They even mentioned that "These data do not demonstrate an effect of
macronutrient composition, independent of weight loss, on insulin
sensitivity in obese subjects without diabetes." This even implies that
high-carb diets are not worse for insulin sensitivity and causing diabetes
than the equivalent number of protein or fat calories! (This had a
disclaimer about the study's unreliability, small size, etc.)
In summary:
It looks to me that calorie restriction is the clear winner for either kind
of diet. The high-carb diet seemed to be better at improving cholesterol
factors, while the high-protein and high-fat diet seemed to worsen these
factors. (The only good news for Atkins was on the triglycerides, maybe at
the end of the year where the diets were less reliable.) This seems
consistent with my understanding of nutrition. It also gives even more
weight to calorie restriction being more important and the specific
macronutrient ratios being less important.
Disclaimer:
Since the study participants were so poor at following the diets, it is not
clear that any conclusions can be drawn from this study, especially a year
later. Even the study itself has disclaimers and says more studies are
needed. This study is definitely not definitive for anything, is the first
study, is unproven and not reproduced, and at best says Atkins isn't any
worse than other diets. This is not very good support for the diet at all,
despite the media hype for it.
-- Harvey Newstrom, CISSP, IAM, GSEC, IBMCP <www.HarveyNewstrom.com> <www.Newstaff.com>
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