Friday, June 02, 2006

Dual-Use Acronyms (and Food): The GI Index

Well, thanks to some very useful comments delivered to my LJ (all the comments are still going there and to E2, which for the moment is fine, though I hope they'll eventually find their way here), I now understand much more about some of the nutritional issues that may affect, or be affected by, the Uberman schedule.

Right alongside the Scienceblog article about glucose comes this useful blog about the glycemic index (thanks for the link, dsymetry!), which turns out to explain a lot more thoroughly what the issue is with glucose, different types of meals, and sleep.

(More info behind the cut -- click "Read More" at the bottom to see the whole post.)

"Glycemic Index" or GI, by the way, is one of my favorite terms now. It actually has a dual meaning -- but let's not go too quickly; this can get complicated. The GI is a way to differentiate carbohydrates, because, as everyone not obsessed with fad diets knows, carbs are good for you, if they're the right kind in the right proportion (just like fat and cholesterol, and, um, the rest of "food"). The GI index is probably most useful to diabetics, and for their sake at least, foods ought to be labelled with it; but it can be darn useful for the rest of us, too, who are fighting our way through the epoxy lake of industrialized food-manufacture and trying to eat right anyway.

High-GI carbs generally have more glucose, and are the kind most Americans get too much of. The key to them for our purposes is not that they contain "sugar" (because that is actually not the core measure of the Glycemic Index anyway--there is a Glucose Level (GL) measure that does that), but that they digest higher in the gastrointestinal tract than low-GI foods do. (GI is also a common medical abbreviation for "Gastro-Intestinal", so isn't it cool that high-GI foods--those with a high Glycemic Index--also happen to digest in the upper-GI area, and the low-GI foods in the low-GI area? c00l! Yay for easy-to-remember science!)

Low-GI foods, then, as I understand it, are whole grains, pastas, and "resistant carbs" which resist digestion until they make it almost all the way, um, "through". ;) A good quantity of them helps reduce the risk of some cancers, and gives you more constant energy, and is better for dieting folks than the other kind. High-GI foods are going to give you quicker, more quickly depleted energy, and are (generally) more readily stored as fat.

Another possible effect, which the Newsletter I linked to above has a small story on, is that eating a high-GI meal about 4 hours before sleeping can help you fall asleep faster than eating a low-GI meal. Is this because your body is done digesting sooner? Or because you've (run out of energy) in a shorter period of time? Or because of the effects of glucose levels ("sugar-crash") on tryptophan/seratonin levels?

I have no idea--and neither do the scientists; it's just one small study, from what I gather. But it's good to know that a) GI levels have an impact on digestion and sleep, and b) that there's a reliable measure of "good carbs" out there. I will need the carbs for energy, probably, when I'm on Uberman -- I mentioned earlier than even with my less-than-careful diet last time, I found that I needed more and higher-energy food while doing Uberman. But I can't be eating only high-GI foods to fall asleep faster, either! I never did notice a real difference, last time on Uberman, in my sleep quality depending on what I ate...but I will definitely take the GI rating of the food I eat, insofar as I can know it, into consideration in making and recording food-choices this time.

Well, it's always interesting to learn something new!


Oh, P.S. Thanks also to dsymetry, I also learned about "over-training syndrome", which is definitely something to watch for on Uberman. I do do a moderate amount of regular physical exercise now, more than I used to for certain, and it's interesting and relevant that lack of adequate recovery time, or too much non-workout stress, can have such a nasty physical impact. Will definitely watch for those symptoms, just in case.


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