TIPPING THE SCALES TO HEALTH

is now open!

The online world has a wonderful new resource
for desperate dieters and
anybody else who is determined to make health a priority in 2009.

Join old friends and new as we kick the New Year off
with a renewed dedication to health and weight loss!

Tufts study compared women’s cognition on low-carb and reduced-calorie diets

MEDFORD/SOMERVILLE, Mass. — A new study from the psychology department at Tufts University shows that when dieters eliminate carbohydrates from their meals, they performed more poorly on memory-based tasks than when they reduce calories, but maintain carbohydrates. When carbohydrates were reintroduced, cognition skills returned to normal.

“This study demonstrates that the food you eat can have an immediate impact on cognitive behavior,” explains Holly A. Taylor, professor of psychology at Tufts and corresponding author of the study. “The popular low-carb, no-carb diets have the strongest potential for negative impact on thinking and cognition.”

Taylor collaborated with Professor Robin Kanarek, former undergraduate Kara Watts and research associate Kristen D’Anci. The study, “Low-carbohydrate weight-loss diets. Effects on cognition and mood,” appears in the February 2009 edition of the journal “Appetite.”

While the brain uses glucose as its primary fuel, it has no way of storing it. Rather, the body breaks down carbohydrates into glucose, which is carried to the brain through the blood stream and used immediately by nerve cells for energy. Reduced carbohydrate intake
should thus reduce the brain’s source of energy. Therefore, researchers hypothesized that diets low in carbohydrates would affect cognitive skills.

Study participants included 19 women ages 22 to 55 who were allowed to select the diet plan they preferred — either a low-carbohydrate diet or a low-calorie, macronutrient balanced diet recommended by the American Dietetic Association. Nine women chose a low-carbohydrate diet and 10 selected the low-calorie diet.

“Although the study had a modest sample size, the results showed a clear difference in cognitive performance as a function of diet,” says Taylor.

The 19 dieters completed five testing sessions that assessed cognitive skills, including attention, long-term and short-term memory, and visual attention, and spatial memory. The first session was held before participants began their diets, the next two sessions occurred during the first week of the diet, which corresponded to the week when low-carb dieters eliminated carbohydrates. The final two sessions occurred in week two and week three of the diets, after carbohydrates had been reintroduced for those on the low-carb diet.

“The data suggest that after a week of severe carbohydrate restriction, memory performance, particularly on difficult tasks, is impaired,” Taylor explains.

Low-carb dieters showed a gradual decrease on the memory-related tasks compared with the low-calorie dieters. Reaction time for those on the low-carb diet was slower and their visuospatial memory was not as good as those on the low-calorie diet. However, low-carb dieters actually responded better than low-calorie dieters during the attention vigilance
task. Researchers note that past studies have shown that diets high in protein or fat can improve a person’s attention in the short-term, which is consistent with the results in this study.

Participants were also asked about their hunger levels and mood during each session. The hunger-rating did not vary between participants on a low-carb diet and those on a low-calorie diet. The only mood difference between dieters was confusion, which was higher for low-calorie dieters during the middle of the study.

“Although this study only tracked dieting participants for three weeks, the data suggest that diets can affect more than just weight,” says Taylor. “The brain needs glucose for energy and diets low in carbohydrates can be detrimental to learning, memory and thinking.”

Another study where a faulty hypothesis is “confirmed.” What does the study actually say?

The LC participants was told to eat 0 carbohydrates during week 1, and that’s when the “cognitive impairment” was recorded. Why 0 carbs? I know of no lowcarb diet that recommends such a low carb intake, even during an induction phase.  And hadn’t they heard about “induction flu?” The test was done at a time when the body was switching over from burning glucose to burning fat and many people feel slighlty sick during this period.

I am convinced that if the test had been done at a later stage, no “impairment” would have been found. And, actually, it wasn’t. The test was repeated at week 2 and 3 after the LC group had “added back carbs.” So how much carbohydrate did they add back? 5-8 grams in week 2, and another 5-8 in week3. They were still below Atkins’ induction levels! And that very small amount of carbs eliminated the “cognitive impairment” recorded in week 1.

Perhaps they should have tested in week 2 and 3 without adding any carbs back. Or even better, started out with a higher level of carbs as recommended by any lowcarb diet. What would the results have been then? Would any “impairment” have been detected?

But of course, any impartial evaluation was not the purpose of the study. They just wanted to show that LC diets are bad for you.

For instance, they conclude:

Performance on the reverse digit span was significantly worse for participants in the low-carbohydrate condition after 1 week on the diets relative to the ADA diet (mean number correct + SEM). Performance at other time points did not vary as a function of diet.

“Performance at other time points did not vary as a function of diet?” That’s not exactly true. The LC dieters showed a better performance than the ADA dieters in week 3, at the time limited to 10-16 grams of carbs per day.

Or:

……..suggests that the two diet groups reported similar confusion rates for the 48-h and 3-week test sessions, but that ADA dieters reported higher confusion for the 1-week and 2-week sessions

The majority of the tests showed no difference between the groups.

And this “study” proves that low carb diets cause “‘cognitive impairment?” I question the cognitive ability of the researchers!

So does Kimorexia: Benefits of cigarette smoking

I doubt it but it wouldn’t hurt to try. Kimkins Review has a call-out for how you can help. Only by getting some low carb proponents on the panel can we influence how the new food pyramid will look. At least we can hope for some improvement.

And quoting Dr. Michael Eades who got the question why it matters as nobody follows the USDA recommendations anyway:

I explained that although he may not pay attention to them, plenty of other people do. The law that established the guidelines mandates that every bit of food or money for food that the government doles out has to follow the Nutritional Guidelines. Approximately 54 million people are fed daily by the government, and they all have to be fed according to the guidelines. Who does the government feed? The military, people in the prison system, school lunch programs, numerous people who receive commodities from Uncle Sam, Federally funded daycare centers, the list goes on and on. So the Nutritional Guidelines are not a meaningless, harmless little bit of government doodling - they are of great importance. It would be nice to see them move away from a diet that composed primarily of carbohydrate. The only way this will happen is to get some low-carb advocates on the panel.

I never paid much attention to the food pyramid but looked at it on Dr. Eades blog. It looks a lot more scary when you see it that way than just looking at the numbers above (not that 65% carbs don’t look scary in themselves). No wonder people get fatter and fatter.

Just to amuse myself, I decided to redo the food pyramid for a low carb woe (way of eating). I didn’t add any food items so the “fats” segment ended up pretty empty - just a jar of mayo that is on the top in the USDA version.

It didn’t surprise me that the pyramid is pretty much flipped upside down. But notice that the “oh so important veggie” segment is in the same place and no smaller in the lowcarb variant.

And to further amuse myself, I created a Kimkins food pyramid. This one was simple. Just erase most of the food items. The pyramid ended up a lot smaller too as the typical Kimkins menu is 500 - 600 calories as compared to the 2,000 in the USDA pyramid.