The amount of will-power or self-regulatory strength that is used up when making choices depends on the type of choice being made. Autonomous choices don't result in ego-depletion. If you're doing things you want to do, things you like doing, your brain doesn't have to expend 'will-power'.
Choice and Ego-Depletion: The Moderating Role of Autonomy
The self-regulatory strength model maintains that all acts of self-regulation, self-control, and choice result in a state of fatigue called ego-depletion. Self-determination theory differentiates between autonomous regulation and controlled regulation. Because making decisions represents one instance of self-regulation, the authors also differentiate between autonomous choice and controlled choice. Three experiments support the hypothesis that whereas conditions representing controlled choice would be egodepleting, conditions that represented autonomous choice would not. In Experiment 3, the authors found significant mediation by perceived self-determination of the relation between the choice condition (autonomous vs. controlled) and ego-depletion as measured by performance.
Claims that the extent to which will power is exhaustible depends on one's belief about it's exhaustibility: http://www.sciencedaily.com/releases/2010/10/101014144318.htm
That was my first thought, but it appears they accounted for that — "The researchers designed a series of four experiments to test and manipulate Stanford students' beliefs about willpower. After a tiring task, those who believed or were led to believe that willpower is a limited resource performed worse on standard concentration tests than those who thought of willpower as something they had more control over."
This is a great insight, but it's slightly off in that the term "willpower" groups together several unlike things, some of which are affected by glucose depletion and some of which are not. Willpower includes both the ability to resist things which are tempting but unwise (ie, impulse control), and to do things which are necessary but unattractive (ie, motivation). The paper deals exclusively with impulse control, which is linked to glucose levels; motivation, on the other hand, is not. In my experience, elevated blood glucose levels provide an excess of the former kind of willpower, but sap the latter.
Apparently, the brain also burns lactate.
Lactate fuels the human brain during exercise Bjørn Quistorff, Niels H. Secher, and Johannes J. Van Lieshout Abstract
OP's paper gives at least some (but not many) examples where manipulations in glucose levels modified cognitive performance. However they mostly just observed that attention leads to lower glucose levels, which would also be observed if glucose would be one among many energy sources.
Also, before eating all that candy, note (from OP's paper)
One study administered glucose drinks to participants and found that poor glucose tolerance (indicated by glucose levels remaining high after the person consumed the drink) was associated with poorer performance on a dichotic listening task, which is another classic attention- control task and requires participants to ignore infor- mation presented in one earphone in order to track and process the information coming in the other ear (Allen, Gross, Aloia, & Billingsley, 1996).
I.e. high glucose levels lead to lower cognitive performance.
Perhaps your conclusion misinterprets the results. The glucose tolerance test was given at a different time than the cognitive test, and so no connections between glucose levels and performance should be made. The idea is that ineffective glucose metabolization is an individual difference associated with lower cognitive performance.
For future reference, if the link goes dead (pjeby, add this to the article): the paper is
Matthew T. Gailliot, Roy F. Baumeister. (2007) The Physiology of Willpower: Linking Blood Glucose to Self-Control. Personality and Social Psychology Review, Vol. 11, No. 4, 303-327
I would try this, but I don't like water.
If it gives you stomach problems, note that adding something to it can break the surface tension that causes the problems. My wife prefers tea to water for this reason, but in a pinch can just throw a bit of stevia or almost any other powdered substance into the water to make it drinkable.
It's probably crossed my palate at some point. I half-suspect that I'm tasting something that leaches out of the plastic bottles into the water, rather than something that's supposed to be there, when I react badly to bottled water; I'd probably need to do tests with empty bottles and tap water and a blindfold to be sure.
Hopefully whatever is leeching out of the bottles isn't carcinogenic.
The material the bottle is made out of should be printed on it somewhere (probably the bottom, by the recycling triangle). PET or PETE is considered safe by the FDA, as well as a few others, but there are some that are known to leach. Also, reusing bottles and heating bottles are generally poor ideas, unless you know the material it's made from is designed for that.
Have you tried measuring your glucose levels?
Also if you do it wrong, frequent glucose spiking means insulin resistance means metabolic syndrome, and you really don't want that.
Also if you do it wrong, frequent glucose spiking means insulin resistance means metabolic syndrome, and you really don't want that.
Interesting link; I appear to have at least 5 of those 9 insulin resistance symptoms, and have had them pretty much since I got a car and stopped bicycling and walking everywhere. I think I just got a lot more motivation to exercise. ;-)
There's an interesting discussion of this on Hacker News http://news.ycombinator.com/item?id=661984
This paper (PDF)1 looks more than a little interesting:
I find this interesting, in that the days I get less work done (due to e.g. spending more time on Less Wrong) are often days when I don't eat breakfast right away, and am generally undereating (like today).
References
1. Matthew T. Gailliot, Roy F. Baumeister. (2007) The Physiology of Willpower: Linking Blood Glucose to Self-Control. Personality and Social Psychology Review, Vol. 11, No. 4, 303-327