Monday, July 6, 2009

Why quitting smoking leads to eating more

Paper we’re looking at: Self-Control Relies on Glucose as a Limited Energy Source: Willpower Is More Than a Metaphor Matthew T. Gailliot, Roy F. Baumeister

What is self-discipline, exactly?
Why does quitting smoking lead to eating more?
Why are we more likely to be peevish and argumentative at certain points during the day?

These are some questions we’ll be talking about while looking at this paper.

I LOVE this paper. It explains a lot about things that plague us every day, and it provides us with some really easy guidelines to follow to get better performance in just about any area.

That sounds pretty self-helpy. But unlike traditional self helpy stuff, this is backed up with some very cool evidence.

First, let’s define Self Discipline (or Self Control) as the ability to control or override our thoughts, emotions, behavior or urges. It’s what keeps us from following through on our road rage fantasies, what keeps us from telling our boss to stuff it where the sun don’t shine, and what keeps us from ordering that second helping of dessert.

There’s evidence to link self discipline with:
• Healthier interpersonal relationships
• Greater popularity
• Better mental health
• More effective coping skills
• Reduced aggression
• Superior academic performance

Not to mention less susceptibility to drug and alcohol abuse, criminality, and eating disorders.

Not too bad – It’s probably something worth cultivating.

When you ask most people what self discipline is, though, you get answers like “It’s mind over matter.” Or “You either have it or you don’t.” People sometimes talk about mental energy (consider how much more likely you are to say the first peevish thing that pops to mind when you’re tired or frustrated, vs. when you’re feeling full of energy).

The researchers on this paper ask a very cool question – They asked “Where does this mental energy come from?” They guessed that it was linked to blood glucose (that wonderful substance that feeds our brain, among other things).

Here’s a scary thought: Every time you resist a temptation (ie exercise self discipline), it draws from your ability to resist ANY OTHER temptation. In one experiment, resisting the temptation to eat freshly baked cookies caused participants to give up much sooner on a later task that required them to concentrate & think. The 2 seem disconnected, but they’re both aspects of self discipline (resisting the urge to eat, focusing on a task & applying mental resources to trying to solve it).

Think of it like a gas tank – you can only use so much self discipline before it all runs out. In the case of our brains, the fuel is glucose.

Here are some other things that fall under the bailiwick of self-discipline (and hence rely on our supply of blood-glucose):

• Suppressing stereotypes and prejudice
• Coping with thoughts and fears of dying
• Controlling one’s monetary spending
• Restraining aggression
• Managing intake of food and alcohol

Here’s the long and short of it – Just about everything our brains do (consciously & unconsciously) relies on glucose to some extent, but the vast majority of things our brains do aren’t affected by minor fluctuations in glucose levels (like, say, going 8 hours without eating). However, this isn’t the case with tasks that require a lot of conscious cognitive resources (such as logical thinking, reasoning, and urge suppression).

So all of this is pretty cool, but there’s no evidence that there really IS a link between self control & blood glucose – At least, there wasn’t until the authors did the experiments that made up this paper.

They attacked it from a lot of angles – 9 studies were done to find evidence of a link between blood glucose & our ability to exert self control.

In the first two experiments, they looked at the difference in blood glucose between 2 groups before & after a task. In group 1, the task required no self control, and in group 2 it did. They found the group that exercised self control had lower blood-glucose levels afterwards than group 1.

The next 4 studies affirmed that people “use up” their self control – in other words, that the more self control they exerted, the less glucose they had available to exert self control as the tasks wore on. Indeed, they found that without a “re-fueling”, people exerted less & less self control as time went on.

The final 3 studies dealt with this “re-fueling” issue – Both groups had their self control tested, one group was allowed to have an energy drink, and they did another test of self control. The energy drink group showed much greater self-discipline/focus/etc. This is because the energy drink quickly converted to glucose, which gave a nice, quick “re-fuel.”

One of the scariest findings of this paper is this – While glucose depletion causes impairment of certain abilities (logical reasoning, focus, self-discipline, etc), it doesn’t necessarily cause a loss of motivation. So it’s very possible to be unaware that you’re functioning well below your peak, and keep ‘hitting your head against the wall’, so to speak – when all you really needed was a break to have a quick bite to eat & let the body start feeding the glucose to your brain.

And just as a heads up – it takes a minimum of 10 minutes to go from food in mouth to glucose, and sometimes much longer, depending on the food. That suggests that if you’re feeling sluggish, or irritable, or are having a problem that you just can’t seem to work through, a 15 minute break to have a bite to eat might be your best course of action.

It also means that dieting is a CRUEL, CRUEL trick – just as you need more willpower to fight the urge to eat that brownie, you’re denying yourself the glucose you need to fuel that willpower.

So what’s the long and short of it?

Eat breakfast – It’ll start your day off by replenishing the glucose you used up in sleeping, and give you the fuel you need for the first part of the day.

Snack – There’s a shelf life for the batteries that power your willpower. And it’s about 4 hours, give or take. Which means that if you have breakfast at 7:30 before you leave your house, and work through till 12:30, that last hour or two was at a much lower level of focus and/or logical reasoning ability than you’re capable of. Have a snack every couple of hours.

Be aware of your glucose gauge – Most importantly, start to become aware of the signals that your brain is giving you. Recognize the signs of low-glucose, and when you feel them, for the love of all that’s holy go eat something!


  1. Wow really very nice and good information you share here. I read your entire post and really superb information you share here on funny stuff. thanks for your information.

  2. Thanks for the good words, and I'm glad you're enjoying the posts! :)

    There's a whole lot more coming, so hopefully you get as much out of the future posts as this one. :)

  3. Great read! Thanks.