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Low carbs cause memory loss? Not so fast!

Recently the media had a field day reporting a Tufts University study (1) that supposedly showed low carb diets have a negative effect on memory. Once again, the media got it wrong, and in two critical ways. First, they reported conclusions that were not found by the study and two; they omitted findings that were critically important to understanding what was actually discovered.

In the study, half the people were put on a low-calorie high carbohydrate diet and the other half were put on a low-carb diet. The researchers then gave the participants tests for long and short-term memory and attention after one, two and three weeks on their respective programs.

The first thing to note is, the low-carb group was on a basically no-carb diet, at least for the first week. And they did indeed score slightly worse on the reaction time part of the test that week. (What the media buried deep in their reporting was, the low-carbers performed better than the other group in tests that measured attention and the ability to stay on task!)

Also buried in the reporting - when it was reported at all - the low-carbers improved on the tests as the study went on.

These results are really exactly what you might expect. There is a short period of adaptation when the brain and body switches over to fat burning and ketones as a fuel source, which most certainly was happening in this situation, as the dieters were consuming no carbohydrates whatsoever. This adaptation period is natural and mental and physical performance returns as soon as the adaptation period is over. Stephen Phinney, PhD has even done research showing that, after a brief period of adaptation, world-class cyclists on a ketogenic diet are back to cycling at their previous levels of intensity and endurance within a month.

The second detail that was omitted involves the fact that limited carbohydrates were introduced in the second week - much like the OWL stage of Atkins - and the performance on the memory tests went right back up.

While the researchers put out a news release saying, “diets low in carbohydrates can be detrimental to learning, memory and thinking,” this was not supported by their research at all. Larry McCleary, MD, one of the country’s top neurosurgeons and author of “The Brain Trust Program” says, “there is a groundswell of medical evidence that documents how too much sugar can make the brain shrink, wither, atrophy and just plain work badly.” (2)

It’s interesting that a study last year in the September issue of the American Journal of Clinical Nutrition that compared low-fat to low-carb diets found improvements in mood and memory in both groups. And it’s also worth noting that a Colorado biotech company called Accera is currently working on a drug to help the liver create more ketones because their Phase ll studies showed rapid and significant cognitive improvements in Alzheimer’s when patients were provided with this alternative fuel source. (3)

Let’s remember that the Atkins Nutritional Approach is not a no-carb diet - like the one used in the first week of the Tufts study. With the Atkins Nutritional Approach, good carbs are added back to your diet as your body adapts to better nutrition. Today’s refined Atkins Nutritional Approach places greater emphasis on a balance of the right healthy foods and active lifestyle, allowing more flexibility when it comes to healthy carbs. And as far as memory goes? “If you want to age your brain, just eat the typical diet most Americans consume,” says Dr. McCleary.

1) Appetite, Feb 2009
2) Interview with Larry McCleary, MD,

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