Willpower as a muscle

The implications of this muscle metaphor are vast. For one thing, it suggests that making lots of New Year's resolutions is the wrong way to go about changing our habits. When we ask the brain to suddenly stop eating its favorite foods and focus more at work and pay off the Visa…we're probably asking for too much.

The willpower-as-muscle metaphor should also change the way we think about dieting. Roy Baumeister, a psychologist at Florida State University who has pioneered the muscle metaphor, has demonstrated in several clever studies that the ability to do the right thing requires a well-fed prefrontal cortex.

That's from The Science Behind Failed Resolutions by Jonah Lehrer (the man behind the blog The Frontal Cortex).