It's been open warfare in the cutthroat
world of diet doctoring since the March 7 issue of the
Journal of the American Medical Association carried
a study comparing four leading plans in women, and declared
the Atkins diet the clear winner.
Atkins not only appeared to leave
two other 'private' diet plans in its wake, the Ornish
plan of Dr Dean Ornish and the Zone plan of Dr Barry
Sears, but it also outperformed the US government's
own diet recommendations. Across the board, though,
participants had one key thing in common: almost none
actually stuck to the rules. To the study's critics,
this is its greatest weakness; to its defenders, its
greatest strength.
DIETS
BY DESIGN
In a nutshell, the Zone demands a 40:30:30 ratio of
carbohydrates to protein to fat. The Ornish plan is
very high in carbohydrates and very low in fat. The
LEARN plan, based on the US Department of Agriculture's
food pyramid, is quit similar to Ornish, with plenty
of carbohydrates and low fat. It also places the most
emphasis on lifestyle changes like exercise. The Atkins
plan eschews carbohydrates but allows plenty of fat,
and demands lots of protein to suppress appetite.
Overall, after 12 months, the average
Atkins dieter had lost 4.7kg. Ornish dieters lost an
average 2.2kg, and Zone dieters an average 1.6kg. Those
following Yale University's LEARN diet (Lifestyle, Exercise,
Attitudes, Relationships and Nutrition), the state-sanctioned
way to lose weight, lost an average 2.6kg.
But Atkins scored on more than
just pounds shed. Participants' lipid levels and blood
pressure were also measured, and the Atkins dieters
did surprisingly well here. The Ornish diet was best
at reducing LDL cholesterol, but the greatest increase
in HDL cholesterol — and the greatest reductions
in triglycerides and blood pressure — were seen
in the Atkins group.
The study had 311 subjects —
hardly huge but bigger than any well-controlled study
to date. All were premenopausal women aged 25 to 50
with a body mass index between 27 and 40.
CHEATERS,
THE LOT
To be fair, the study didn't really compare the four
diet plans. What it did was compare how real people
fared when given one of the diet books and told to get
on with it. Each group also attended eight weekly classes
explaining their plan. Participants had to buy and prepare
their own food. And then they broke all the rules.
The study "had a good concept and
incredibly pathetic execution," Dr Barry Sears, creator
of the Zone diet, complained to the Associated Press.
"People didn't really follow the
diet I recommend. What [this study] really found was
that if you give people a book and a few classes with
a dietician, they won't follow the diet very well,"
Dr Ornish told the Baltimore Sun.
The Atkins dieters nearly tripled
their permitted carbohydrate intake, while the Ornish
dieters ate three times their allowed fat limit. LEARN
dieters doubled their permitted saturated fat targets.
Zone dieters mostly exceeded both their carb and protein
limits.
LAW
OF LOW-CARB
The study's lead author, Dr Christopher Gardner of Stanford
University, admits he was one of those who initially
dismissed very low-carb diets like Atkins. Now, he has
several theories to explain why Atkins outperformed
the others.
For on thing, he suspects many
people underestimated the simplicity of the message
to lower carbohydrate intake, and what a big impact
it would have. "Both the Atkins and the Ornish plans
are fairly simple. Atkins says 'severely restrict your
carbohydrates', while Ornish says 'severely restrict
your fat'. The average American diet is about 45-50%
carbohydrate and about 35-40% fat, so logically it would
seem that if you're going to restrict one of those two
you'd get more bang for your buck with carbohydrates,"
he explains. "It could also be that Atkins cutting back
so strictly on sugared, refined carbohydrates may go
to the heart of what led to this rise in obesity in
the first place," he adds.
A third plausible explanation,
he says, has less to do with the carbohydrate than with
protein. "The women in the Atkins group not only ate
the least carbohydrates, they also ate the most protein
and the most fat. In half a dozen or so recent studies,
protein seems to be winning in terms of satiety, appetite
reduction, weight loss and metabolic profile improvements."
LONG-TERM
WOES
Nutritionists have always said that over the long-term,
a high-protein diet may disrupt kidney function or could
even leach calcium out of bones. "Given that our study
was only a year in length and didn't measure kidney
function or bone density, I'd have some reservations
about recommending high-protein diets," Dr Gardner agrees.
In fact, he isn't really recommending
Atkins. "It isn't the solution for the obesity problem,"
he says. What this study showed most clearly was how
difficult it is to change people's habits.
All four treatment groups showed
more weight loss at six months than at 12. Although
lipid profile and blood pressure continued to improve,
participants were regaining weight at the study's end,
and the gap between the four plans was narrowing.
Nevertheless, the findings would
have pleased the much-maligned Dr Atkins. His ideas
have been considerably rehabilitated since his death
in 2003, when the world's media falsely reported that
he'd died obese from a heart attack. In fact, he suffered
a heart attack due to cardiomyopathy, and survived it.
He died the following year from head injuries after
slipping on the ice in front of his clinic.
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