Recent media reports have publicized the short-term
weight loss that sometimes occurs with the use of
low-carbohydrate weight-loss diets. Some of these
reports have distorted medical facts and have ignored
the potential risks of such diets. Past experience
with the fen-phen drug combination and other
weight-loss regimens has shown that some people may
disregard even serious long-term health risks in hopes
of short-term weight loss.
The American Heart Association,1,2 American
Dietetic Association,3 and the American Kidney Fund4
have all published statements warning about the
various dangers associated with low-carbohydrate,
high-protein diets. We would like to notify you of (1)
the potential risks from the long-term use of
low-carbohydrate, high-protein diets, (2) currently
circulating misunderstandings and deceptive statements
made in support of such diets, and (3) the
establishment of a registry for individuals who feel
they may have been harmed as a result of following a
low-carbohydrate, high-protein diet.
What Is a Low-Carbohydrate Diet? The theory
behind low-carbohydrate diets is that if dieters avoid
foods containing carbohydrate, they won't gain weight.
JAMA Call For More
Studies on Low Carb Diets
More Evidence Needed for Low-carb Diets
Researchers have expressed the need
for long-term studies on the effects of
low-carbohydrate diets. A review of this currently
popular regime suggests that although successful, and
with no obvious short-term adverse effects, it is not
clear how the diet impacts people in middle age.
People who go on low-carbohydrate
diets typically lose weight, but restricted caloric
intake and longer diet duration are the biggest
reasons why, according to the study from Stanford
University Medical Center and collaborators at Yale
University.
“”Low-carbohydrate diets have been extremely
popular as of late, and the lay press has suggested
they’re a safe and effective means of weight
loss,”" said lead author Dr Dena Bravata,
social science research associate at Stanford’s
Center for Primary Care and Outcomes Research.
“”While these diets are effective in the short
term, weight loss results from reduced calories, not
carbohydrate restriction.”"
The study appears in the 9 April issue of the
Journal of the American Medical Association.
Despite the popularity of low-carbohydrate/
high-protein diets, and the concern of some in the
medical community that these diets are too high in fat
and can lead to kidney and liver problems and other
health risks, Bravata said little evidence exists on
the efficacy and safety of low-carbohydrate diets.
Bravata and her colleagues collected literature on
low-carbohydrate diets published between 1966 and
2003. They reviewed a total of 107 diet studies, which
involved 3,268 people from around the world. The
studies were small and heterogeneous, with
carbohydrate and caloric intake, diet duration and
participant characteristics varying greatly.
However all of the studies had two things in
common: none had participants with a mean age over 53
and none of the randomised and controlled studies
lasted longer than 90 days.
“”Information on older adults and long-term
results are scarce at best, and this should be kept in
mind when looking at our findings,”" noted
Bravata.
The researchers’ meta-analysis found that people
on diets of 60 or fewer grams of carbohydrates a day
(a threshold used in some of the popular
low-carbohydrate diets) did lose weight. But the
weight loss was associated with restriction of caloric
intake and longer diet duration, not with reduced
carbohydrate intake. It also found that the greatest
weight loss occurred among those participants on diets
with the highest baseline weight and lowest caloric
content.
“”The greatest predictors of weight loss appear
to be caloric intake and diet duration,”" she
said. “”The findings suggest that if you want to
lose weight, you should eat fewer calories and do so
over a long time period.”"
The researchers found no significant adverse
effects on cholesterol, glucose, insulin and
blood-pressure levels among participants on the diets.
But, Bravata stressed, the adverse effects may not
have shown up within the short period of the studies.
She also said losing weight typically leads to an
improvement in some of these levels, so this could
have had an impact on the numbers.
The researchers concluded that there is insufficient
evidence overall to make recommendations for or
against using the diets. Bravata said studies are
now needed on the role of exercise in weight loss
(as exercise information was excluded from this
analysis), the long-term effects of these diets and
the effectiveness and safety of these diets for
people over the age of 53.
Co-author Christopher Gardner agreed that more
studies on low-carbohydrate diets are needed.
“”There wasn’t a lot of information from
well-designed, randomised controlled trials…The
obesity epidemic involves people having weight
problems for years or decades, and we need long-term
data on these diets’ effectiveness and
safety.”"
~Compliiments of SS
