Low carb diets and cognitive function
Low-carbohydrate weight-loss diets. Effects on cognition and mood:
To examine how a low-carbohydrate diet affects cognitive performance, women participated in one of two weight-loss diet regimens. Participants self-selected a low-carbohydrate (n = 9) or a reduced-calorie balanced diet similar to that recommended by the American Dietetic Association (ADA diet) (n = 10). Seventy-two hours before beginning their diets and then 48 h, 1, 2, and 3 weeks after starting, participants completed a battery of cognitive tasks assessing visuospatial memory, vigilance attention, memory span, a food-related paired-associates a food Stroop, and the Profile of Moods Scale (POMS) to assess subjective mood. Results showed that during complete withdrawal of dietary carbohydrate, low-carbohydrate dieters performed worse on memory-based tasks than ADA dieters. These impairments were ameliorated after reintroduction of carbohydrates. Low-carbohydrate dieters reported less confusion (POMS) and responded faster during an attention vigilance task (CPT) than ADA dieters. Hunger ratings did not differ between the two diet conditions. The present data show memory impairments during low-carbohydrate diets at a point when available glycogen stores would be at their lowest. A commonly held explanation based on preoccupation with food would not account for these findings. The results also suggest better vigilance attention and reduced self-reported confusion while on the low-carbohydrate diet, although not tied to a specific time point during the diet. Taken together the results suggest that weight-loss diet regimens differentially impact cognitive behavior.
Also at ScienceDaily. Small N’s. What were the N’s on the Creatine studies???
Labels: IQ
It would also be interesting to see if race mediated the results (not here, but in a larger study). If digestive system is more adapted to agriculture, you should suffer more strongly during the loss of carbs.
The only thing a low-carb diet will do is turn you into a couch potato — the opposite of what the hippies wish. You need lots of energy to do anything worthwhile — i.e., energetically expensive, like being active or using your calorie-hogging brain.
I dunno. I’ve been low-carbing it (not obsessively, but consistently) for about a year, and I’ve never felt better. Eating satisfying amounts of excellent food, active and alert … Time for y’all to read a little Gary Taubes.
Of course maybe this is just a case of me thinking I’m feeling good. But how could we tell the difference?
Deconstructed masterfully (as usual) at:
http://high-fat-nutrition.blogspot.com/2008/12/dodgy-danci.html
Just as an aside, it seems like historically, people on low-carb diets or low-calorie diets or low-meat-high-carb diets were probably in very different situations, and those situations were consistent enough that the diets may trigger some kind of “mode switch.”
For example, high-carb diets with a lot of grains seem like they’ve been associated mostly with agricultural settlements. A sudden burst of sugar in a diet was probably mostly associated with summer/early fall, when lots of berries and fruit ripened. A low-carb diet seems like what you’d eat during winter if you were mostly dependent on hunting and fishing.
I wonder if there are any reliable behavioral changes that come about from those different diets. Do years and years of reliance on one grain for most of your calories put you into docile peasant mode? Do years and years of low-carb diet put you into hungry hunter/gatherer mode? Etc.
Uh, Agnostic, you do realize that fats provide more energy pound for pound than carbs, right? And that your brain can consume the ketone bodies released during lypolysis, right? But hey, who needs biochemistry when you can make jokes about hippies, right?
Like Michael I switched to a low carb diet several months ago, and if anything I’m less sluggish than I was before. Insulin signaling increases tryptophan uptake into the brain, which then gets converted to serotonin and then melatonin, so if anything a high carb diet will make you more tired all else equal. Hence the increased vigilence and lower brain fog for the low carbers. You can try this experiment yourself: have an all-meat dinner one night and an all-starch dinner the next, and see which one you feel drowsier after. Repeat experiment until convinced.
It makes sense that people who are already low-carbing it would be more affected on memory tasks by total carb withdrawal — they’re running closer to the limit. Would be interesting to see this experiment repeated with subjects on a complete no-carb diet for three weeks, though, i.e. with more time for their body to adjust to it.
Also, note that all the memory effects vanished with a mere 8 g/day of carbs. Which would seem to indicate that in fact you don’t need much at all. Especially since a low-carb diet will tend to be higher in protein, which your body can also derive glucose from.
Low-carb, high-meat diets were (and it would seem, still are) used to control seizures in children who didn’t tolerate anti-epileptic drugs well.
I would be skeptical about any claims that such diets didn’t alter human cognition in some important way.
I went low carb after reading “Good Calories, Bad Calories” and some other books. I went from being hungry almost constantly and feeling almost painfully tired a few hours after every meal to having much more energy. I can also go between meals without snacking every hour. I really don’t see myself ever going back to my old way of eating.
The twenty pounds lost effortlessly was nice too but the higher energy levels are the best part of this way of eating.
A regular (lurking) reader
So, I am interested in experimenting, so how low is low?
Eric,
If one goes by Atkins’, less than 20 g is low. They don’t suggest this low level for more than a week or two. After that it’s about < 80 g. Of course, this is dependent on your own metabolism.
My experience with low carb dieting is that it works, you have energy and you can satisfy hunger with a low amount of food (which is what I believe causes the weight loss to a large degree) but I always have trouble concentrating and have headaches. In short, I always feel I have had too much coffee, which is why I’m off it as I pursue graduate studies.
I’m not a count the calories kind of person. I just completely eliminated sugar, wheat, more than one piece of fruit a day, potatoes, and added more green veggies, meat, dairy and fat (not vegetable oils). I have experimented with different foods now and anything higher in sugar makes my energy level crash. I know I eat more that 8 grams but under 40-50.
Eric, if this is the first time you’ve ever tried low-carb eating, you’re in for a treat. And some challenges.
ource.blogspot.com/
Some online sites you might find useful:
http://high-fat-nutrition.blogspot.com/
http://www.proteinpower.com/drmike/
http://wholehealths
To answer your question, it depends. Entering ketosis normally requires restricting carb intake to < 20g/day, but keeping it under 80g/day is considered the threshold for “low-carb”. (Note this is net intake after subtracting fiber.)
Have fun – low-carb is for everyone, but not everyone has the fortitude to get through the initial stages and stick with it in a post-Neolithic world… ;-)
Is ketosis desirable for stamina and alertness? I’m barely interested at all in losing weight, and it probably wouldn’t take much to make me do so. I’m very interested in vitality and cognition. I’m a 5’11″ twig, probably 98th percentile as a USA male for skeletal [length/width], 4th percentile muscularity at best, and low fat except for a pretty serious belly of visceral adiposity, rather recent, which I might as well shed – its a mortality predictor, though I am not sure it’s been shown to be causal.
Definitely, I will make sure that 100% of whatever carbs I eat are low-glycemic, and I suppose it will also help to dilute them rather evenly into all the other food.
BTW nice to meet you Michael I’ve read 2blowhards quite a lot.
Eric, your question regarding ketosis is an excellent one – and one that usually starts massive flame wars.
So I really suggest spending a fair amount of time on the sites I referenced above, plus following up on whatever useful links or search terms you discover. Should take you several weeks… ;-)
My take is that being in a ketogenic state is healthier and is the default state of H. sapiens. What little glucose is necessary (some parts of the brain, and a few other tissues) is fulfilled by protein conversion to glycogen.
This is not to say high-carbohydrate diets are necessarily bad – they’re not, but they’re not optimal. And there are all sorts of things to worry about when consuming high-carb: avoiding large amounts of PUFAs, getting the correct ratio of PUFAs you need, like omega-6 and -3, avoiding anything more than small amounts of fructose, and dealing with plant anti-nutrients.
Regarding your visceral fat – definitely check out the sites referenced.
I’ll stop here – I sense the pitchforks coming out…