The Truth Curve

Self-control (or willpower) sounds great on paper, that is until you actually have to summon it to accomplish something you’re not really motivated to do, such as change a bad habit.  It works just fine once or twice or even ten times, but pretty soon, when motivation wears off, self-control vanishes too.

Why is this? Why would self-control be so difficult to call upon time and time again?  Wouldn’t it be great if you could just tell yourself that you’re going to exercise three times a week for the rest of your life and actually do that?

Before delving into this, what is self-control?  “Self-control is the ability to control or override one’s thoughts, emotions, urges, and behavior,” (Gailliot et al., 2007).  Self-control is involved in a lot of daily behaviors such as refraining from overspending, suppressing stereotypes and prejudice, coping with fears, and restraining aggression.  However, using self-control is not without great cost.  According to a growing body of research led by Baumeister, exercising self-control uses glucose, which is the body’s fuel.  Our bodies run on glucose and therefore, our brains do too.  Our brains are expensive though, using 20% of the calories we consume while accounting for only 2% of body mass. 

The research suggests that glucose is not exactly used uniformly in the brain; that some mental tasks use more glucose than do other mental tasks.  Mental tasks that are effortful, but not ones that are automatic, use up lots of glucose.  Self-control is one of the most effortful tasks, requiring you to suppress an impulse or resist performing some behavior.  Automatic or habitual behaviors are not effortful and likely use much less glucose.

Since a single act of self-control uses up lots of glucose, the glucose gets depleted, leaving little glucose available for further acts of self-control, even across different domains of life.  So, once you’ve exercised your self-control resisting telling your boss that he’s an idiot, you have no resources left to control your temper when you get home from work and see a mess left on the floor by your kid.  Your glucose was depleted during the first act of self-control and now you have little left for further acts of self-control. 

In the studies that Gailliot et al. have conducted, to overcome the depletion of glucose, after an initial act of self-control, they give some participants a sugary drink (Kool-Aid with sugar).  Those who are given the sugary drink are able to exercise self-control on subsequent tasks or persist longer on frustrating tasks whereas those who are given the placebo drink (Kool-Aid sweetened with Splenda) fail at further acts of self-control and quit working on frustrating tasks sooner. 

People also differ in how efficiently they use glucose and thus, how well they are able to exercise self-control.  Diabetics and those who are unable to use glucose efficiently (those with poor glucose tolerance) are less able to exert self-control than those who are not diabetic or who have normal glucose tolerance.

The implication seems to be that eating (or drinking) restores glucose, which is then available for further acts of self-control.  In the studies that the researchers conduct, they use sugary drinks to quickly increase participants’ glucose levels, but in real life, this isn’t the healthiest way to get more glucose into the bloodstream.  I am not an expert in this but my understanding is that eating something sugary causes a spike in glucose levels and then a “crash.”  It might be better to eat foods that provide a steady release of glucose.

What the research findings suggest to me is that you can exercise self-control when trying to change a habit but it would require you to constantly replenish your stores of fuel before the intended act of self-control in order to be successful.

Tags: Habits //