Jury Still Out on Low-Carbohydrate Diets
Scientific Evidence Lacking on High-Protein, Low-Carb Diets
WebMD News Archive
Bravata says those findings show that much more research is
needed to evaluate the long-term safety of lower-carbohydrate and very
low-carbohydrate diets as well as their effect on older people who may have
other health issues aside from obesity.
Researchers found that among obese people who participated in
the studies, successful weight loss was linked to limiting calorie intake and
longer diet duration, but not with limiting the amount of carbohydrates they
But Bravata says they found no evidence that these
high-protein, low-carbohydrate diets were unsafe over the short term. The
studies showed the diets had no significant effect on cholesterol, blood sugar
and insulin, and blood pressure levels.
And Bravata says they were also not able to evaluate the role
exercise or ethnicity may have played in the success or failure of the low-carb
diets in promoting weight loss.
In an editorial, George A. Bray, MD, of Louisiana State
University in Baton Rouge, says this study shows once again that "a calorie
is a calorie," and low-carbohydrate diets induce weight loss by reducing
The first low-carbohydrate diet was introduced by William
Banting in 1863. Since then, Bray says, the diets have become a persistent
theme and "cash cow" for authors and publishers of diet books for the
last 140 years because they produce quick weight loss, "something prized by
dieters and diet promoters alike."
But the quick weight loss induced by low-carbohydrate diets is
largely due to excessive urination. After seven to 14 days of this, Bray says
the rapid phase of weight loss slows.
Bray says the more important point is that, "Diets do not
cure obesity. If they did, Banting's diet would have eliminated overweight and
obesity and made the need for new diet revolutions unnecessary."
He says the question of whether a unique diet exists that will
produce lasting weight loss has yet to be evaluated, and long-term studies to
examine this are needed to address this issue.
"Given the increasing prevalence of obesity, studies such
as these deserve the highest priority," Bray concludes.