(Part 1 of my review of Willpower: Rediscovering the Greatest Human Strength by Roy Baumeister and John Tierney is here)
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Sometimes, at the end of what feels like a long day, or a long mental effort, I have a feeling that I often describe as "brain-fried." I've been struggling not to yell at the kids, I've been thinking about a blog post I need to write, I've been trying not to procrastinate the million things I need to do, and I have an inexplicable craving for things like mashed potatoes or chocolate -- and solitude. Tierney and Baumeister use a different term, but I immediately recognized it. They call it "ego depletion," and it is the state of having used up all your willpower.
Yes, "used up." Here are what they have to say about it, based on the research described in the book:
1. Resisting temptation is only one way we use willpower. Three others are
- controlling display of emotion or emotional outburst;
- making decisions;
- and performing physical tasks that require skill, e.g., balancing speed and accuracy.
2. You have a limited supply of willpower. Repeated effort at any of the willpower-using activities depletes it. After trying to control yourself for long enough, you lack the self-control to do any of them. It becomes more difficult to restrain your displays of emotion, to think about decisions you have to make, to practice your skills, or -- yes -- to resist temptations and urges.
3. It's trying to control yourself, not succeeding, that depletes willpower. Even if you give in, you're left with less willpower to work with.
4. When your blood glucose levels drop, your willpower depletes faster.
5. Accordingly, raising your blood sugar (i.e., by consuming food) restores your willpower supply. The fastest way to do this is, of course, easily digestible carbohydrates, but protein and more-healthful, more-slowly digestible carbohydrates also work, albeit more slowly.
6. At low glucose and low willpower, your brain turns its effort to other things. It keeps working and consuming fuel at the same rate, but it gives up on the willpower-consuming activities.
7. One of the things it turns to is trying to get you to raise your blood sugar. Hello, carb cravings!
Tierney and Baumeister point out the obvious "Catch-22" for people who struggle with food cravings here: You need willpower in order not to eat, and you need to eat in order to have willpower.
Just as obvious is that, if what they are saying is true, then folks with impaired glucose tolerance -- insulin resistance, hypoglycemia, diabetes and prediabetes (even, they suggest, premenstrual syndrome!) -- will frequently be in a state of (relatively) impaired impulse control and decisionmaking skills.
We can get a little overfocused on overeating here at bearing blog. Remember that impulse control applies to a lot of different areas of life (and indeed Tierney and Baumeister mention many): drinking and drug abuse, procrastination, violent outbursts, child discipline, studying and schoolwork, performance at a variety of difficult tasks.
I have to go now (procrastinating long enough) but I'll post again with more insights about willpower, not so glucose related, and then try to tie them into some practical tips for behavioral change.