No-Carb Diets May Impair Memory

[Guest guest]

No-Carb Diets May Impair Memory

Memory Improved When Carbs Reintroduced to Diet

By Salynn Boyles

WebMD Health News

Reviewed by Brunilda Nazario, MD

Dec. 12, 2008 - Eliminating carbohydrates from your diet may help you lose

weight, but it could leave you fuzzy headed and forgetful, a new study suggests.

One week after starting a weight loss diet that severely restricted

carbohydrates, participants in the Tufts University study performed

significantly worse on memory tests than participants who followed a low

calorie, high-carbohydrate diet.

The low-carb dieters' memory-test performances improved in the following weeks

after they began eating some carbohydrates.

" The connection between the foods we eat and how we think doesn't really enter

into most people's minds, " study co-author and cognitive psychologist Holly A.

, PhD tells WebMD. " But this study demonstrates that the foods we eat can

have an immediate impact on brain function. "

Carbs Are Brain Fuel

The body breaks carbohydrates into glucose, which it uses to fuel brain

activity. Proteins break down into glycogen, which can also be used for fuel by

the brain, but not as efficiently as glucose.

So it stands to reason that eliminating carbohydrates from the diet might reduce

the brain's source of energy and affect brain function. But there has been

little research examining this hypothesis in people following low-carb weight

loss diets.

The study by and colleagues included 19 women between the ages of 22 to

55 who were closely followed after beginning a low-carb weight loss plan similar

to the Atkins diet or the low-calorie diet recommended by the American Dietetic

Association that includes plenty of fruits, vegetables, and whole grains.

Before starting the diets, the women underwent testing designed to measure long-

and short-term memory and attention. The tests were repeated one, two, and three

weeks after the diet began.

Low-carb dieters ate virtually no carbohydrates during their first week on the

diet. In testing conducted after week one, they performed worse on memory-based

tasks than the women following the ADA diet.

Reaction times for those on the low-carb diet were slower and their

visual-spatial memories were not as good as the low-calorie dieters.

They did perform better than the low-calorie dieters in testing that measured

attention and the ability to stay on task, however.

And their performance on the memory tests improved after week one, when limited

carbohydrates were reintroduced into their diets.

" Although this study only tracked dieting participants for three weeks, the data

suggest that diets can affect more than just weight, " notes in a news

release. " The brain needs glucose for energy and diets low in carbohydrates can

be detrimental to learning, memory, and thinking. "

The study is published in the February 2009 issue of the journal Appetite.

More Study Needed

Australian research scientist Grant D. Brinkworth, PhD, tells WebMD that the

findings, while intriguing, do not prove that low-carbohydrate weight loss diets

affect memory.

In a study published in 2007, Brinkworth and colleagues performed cognitive

function testing on dieters after they had been on either a low-carb or

high-carb weight-loss diet for eight weeks.

Both groups lost weight and showed improvements in mood.

The low-carbohydrate dieters showed slight impairments in cognitive processing

speed, but no difference was recorded between the two groups in working memory.

Brinkworth says if eliminating carbohydrates from the diet does affect memory,

the effect may only be temporary.

" What ( and colleagues) recorded may be an acute, transient effect that

may just be the body readjusting to an unfamiliar diet, " he says. " We really

need studies that examine the long-term impact of these diets on cognition. "

Calls to a representative from the private equity firm North Castle Partners,

which owns controlling interest in Atkins Nutritional Holdings, were not

immediately returned.

View Article Sources

SOURCES:

D'Anci, K.E. Appetite, February 2009; vol 52: pp 96-103.

Holly A. , PhD, professor of psychology, Tufts University, Medford, Mass.

Grant D. Brinkworth, PhD, research scientist, Commonwealth Scientific and

Industrial Research Organization, Human Nutrition, Adelaide, Australia.

© 2008 WebMD, LLC. All rights reserved.