How much glucose is needed to perform 100% brain function ?

[ChristianBBer]

We all know glucose is needed by the brain to perform.

But how much ? I know if you're on a low low carbohydrate diet, your body will produce ketostones ( or however you spell it) to use for energy.

But what if you drop your carb levels to around 150-180 for someone 200lbs+ Is there a "play it safe" level where you should not dip below ?

I only ask because I got to thinking about why people seem to have different cognitive reactions during their diet

[Avaric3]

in for some good answers!

the threads you make are always very good questions. repped

[Capt_Lou]

I am around 115-120 grams a day right now, my manager keeps asking me how much longer so he can get his focused employee back lol

[seifelbadrawy]

I once asked the same exact question. all i remember form the answer is that your brain gets first dibs on energy... so there is no absolute amount of glucose.. if you've been eating 20 grams of carbs a day for a week, then your brain will adapt and learn how to perform on full capacity with that little amount of glucose.. its when there's a sudden drop in blood sugar, when problems occer.. as soon as your brain notices a lower amount of oxygen reaching it, it makes up for it by utilizing the energy elsewhere to get it back to 100 percent brain function. when this happens, you feel weak and sluggish due to a shortage of glycogen stores in the muscles...
probably the dumbest way to answer a smart question..lol..

[Dallas_15]

Proabaly no what your looking for but interesting none-the-less - http://www.fi.edu/learn/brain/carbs.html

[ChristianBBer]

I found this interesting. I researched a study focusing on dieting and cognition performance.

http://ddr.nal.usda.gov/bitstream/10...ND44133744.pdf

Here are some quotes extracted

For comparison, the recommended daily allowance (RDA) for
carbohydrate is 130 g/day based on the average minimum amount
utilized by the brain (FNB & IOM, 2002).

Results showed that during complete withdrawal of dietary carbohydrate, lowcarbohydrate
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 lowcarbohydrate
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.

The ADA diet is a reduce calorie diet without regards to macro nutrient manipulation.

Interesting to note.

Also have to take into factors such as
1. Obsession with food, thus hindering concentration
2. Energy levels thus reducing concentration and the ability to study for long periods of time as a lot of mental energy is needed.

[AlwaysTryin]

Well from my glucose metabolism lecture last year....

"The human brain requires over 120 g of glucose/day.

The brain cannot store glucose or synthesise it’s own glucose"

[TheHeirApparent]

none if u have ketones =)

[Cnstnce]

I once asked the same exact question. all i remember form the answer is that your brain gets first dibs on energy... so there is no absolute amount of glucose.. if you've been eating 20 grams of carbs a day for a week, then your brain will adapt and learn how to perform on full capacity with that little amount of glucose.. its when there's a sudden drop in blood sugar, when problems occer.. as soon as your brain notices a lower amount of oxygen reaching it, it makes up for it by utilizing the energy elsewhere to get it back to 100 percent brain function. when this happens, you feel weak and sluggish due to a shortage of glycogen stores in the muscles...
probably the dumbest way to answer a smart question..lol..

Not sure that the brain adapts that way. If my diet falls below 80gm/day I start getting anxiety attacks, I'm talking fetal position on my kitchen floor uncontrollable crying here. A bowl of oats once saved my sanity. LOL