Mmmm, a hot fudge sundae. The diet is supposed to start today, but surely it can wait until tomorrow -- or maybe the next day.
Many people know what's good for them and choose to do the exact opposite, especially when it comes to diet and exercise. Researchers are turning to the brain to find out what's behind this lack of self-control, a topic discussed in length at the American Association for the Advancement of Science meeting in Boston earlier this year.
In the future, there may be brain-based solutions to help you avoid that sundae; for now, researchers say, we can shape our environments to help us avoid temptation, and make firm commitments to change.
Value judgments and willpower
Pinpointing complex behaviors in the brain isn't simple; we weren't born with the words "impulsivity" and "willpower" etched into particular places on our heads. Scientists are still in the early stages of figuring out how billions of cells called neurons generate particular outcomes, and which circuits do what. But some clues have emerged from recent experiments.
When people who are trying to lose weight are confronted with meal choices, it appears there are two major factors in their decision: taste and health, said Todd Hare, assistant professor of neuroeconomics at the University of Zurich.
Hare's research shows that dieters who successfully turn down fatty temptations such as ice cream put more emphasis on the healthiness of food and relatively less emphasis on the taste.
It is the opposite for dieters who can't say "no" to sweets, he said. They say they're trying to eat healthy, but "they seem unable to shift away from the more automatic, stronger representation of taste," Hare said.
By using functional magnetic resonance imaging, or fMRI, scientists can see how a brain region called the ventral medial prefrontal cortex becomes active in valuing options in predicaments like this.
The ventral medial prefrontal cortex also appears to get involved in certain monetary decisions -- for instance, when researchers present participants with the choice of accepting a large reward later or a smaller reward immediately. Hare's research on this is not yet published, but the phenomenon was described in a 2011 research review.
Scientists have also located a second important brain area for these kinds of decisions: the dorsolateral prefrontal cortex. There is more activity in this region when participants choose options that appear better for them in the long run -- the healthy food item or the larger monetary reward that will arrive later.
The interaction between these two brain regions -- the ventral medial prefrontal cortex and the dorsolateral prefrontal cortex -- is stronger for people who show greater self control with either money or food, Hare said.
"They're working together to shape the way you're going to make your choices."
Scientists are also investigating brain areas associated with turning down temptations.
University of Cambridge neuroscientist Molly Crockett and her colleagues suggested in a study earlier this year that "precommitment" -- voluntarily restricting one's access to temptation -- is more effective at promoting self control than willpower.
In the experiment, men viewed erotic images that they rated according to personal preference. Then, in one task, they could decide in advance that they would not have the option to see the images they rated poorly. In exchange, they could see the higher-rated images after a greater time delay. This is called "precommitment."
In a different task, men were challenged to use willpower to actively resist viewing the lower-rated images while they waited for the higher-rated images. Precommitment appeared to be a better strategy on average.
In impulsive participants in particular, researchers saw more activation in the ventral striatum and ventromedial prefrontal cortex areas during precommitment. These relationships between brain activation patterns and impulsive tendencies suggest that people in general may have some self-awareness about their own self-control abilities.
Are self control problems, such as overeating and overspending, the result of poor willpower or impaired ability to precommit, or both? Further research on these issues could help the development of behavioral or pharmacological interventions, according to the study.
Can we alter brain function for the better?
Currently, we don't have drugs designed to target such brain impairments associated with lack of self control.
But, in theory, a drug of the future could stimulate key brain areas to help people with self-control problems diet or save money, according to David Laibson, professor of economics at Harvard University.
If that sounds too much like science fiction, consider that many drugs
are already on the market to alter brain function for the better -- for example, methylphenidate (Ritalin) for attention deficit disorder and anti-depressants for depression.
Outside the pharmacy, there is a drug to combat exhaustion and enhance attention, used by millions of Americans every day: caffeine. Laibson argued that if these substances are widely accepted, why shouldn't there be options for people who want better control of their food decisions?
The practical realities for a self-control drug are complex, however. Hare cautioned that these brain areas would be hard to target with medicine because a lot of other brain areas would be hit at the same time. No drug could selectively increase activity in the dorsolateral prefrontal cortex alone, for example.
A different approach, which has not been tried, would be to use transcranial magnetic stimulation to temporarily enhance the activity of regions of the brain near the skull. This technique -- in which magnetic fields generate small electrical currents, activating cells in a specified part of the brain -- is being explored for depression patients who don't respond to medication.
A 2010 Nature Neuroscience study used transcranial magnetic stimulation to temporarily inhibit the dorsal lateral prefrontal cortex, and showed that this led to participants making more impatient decisions.
Theoretically, this technology could be applied in the opposite way -- to train relevant brain circuitry to come online during problematic food choices among dieters, so that eventually the person's brain would respond naturally in this way, Hare said.
"If there's enough success with this in conditions such as depression, then I could see that that would be the logical next step," Hare said.
Scientists may also be able to develop behavioral interventions based on brain research -- i.e. how to train and promote self-control. Psychologists, for example, may be able to derive behavioral therapies from the "brain circuit differences that we see in people with different kinds of self control problems," said Joshua Buckholtz, assistant professor of psychology at Harvard University.
Buckholtz has unpublished research suggesting that people with high BMIs and non-obese impulsive people have similar brain chemistry patterns.
Committing to change
To recap: We're bad at self control. Scientists are looking at the brain to figure out how self control breaks down at the neurological level. Such insights could directly lead to interventions in the form of pharmaceuticals or brain stimulation.
In the meantime, what can we do to help ourselves behave more in line with our good intentions, even in the face of temptations?
"The more we recognize the commonality of this problem, the more prepared we'll be to develop solutions to solve a problem, because the solutions end up being the same across all the different domains," Laibson said.
The basis of nonpharmaceutical solutions is the big C-word: commitment. To some extent, most of us are already entrenched in a system of commitments that keep us in line. It's called the workplace.
Journalists publish articles, cashiers scan groceries and teachers grade papers because of systems built into our society that commits them to perform certain tasks, with the threat of punishment -- or not getting paid -- looming over their heads, Laibson said. Managerial structures ensure that employees at every level do what they're supposed to be doing.
"We built this system that is actually well tuned to who we are psychologically," he said. "We're not relying completely on our willpower to do everything. We are letting the system take care of us."
When it comes to money, for instance, many companies offer savings plans that automatically place a fixed percentage of your paycheck into a 401(k) account, with strict penalties if you try to access that money before retirement. Once you sign up, you don't have to think about making the choice every week; it just happens in the background.
"We don't want people to tell us what to do so that we have no freedom, but we do need a little bit of help so that we actually get to work and have a productive day instead of rolling in at 11 a.m.," Laibson said.
Applying that method to food is a lot trickier. Your boss can make you go to a 9 a.m. meeting, but you don't have a Food Manager who prods you to avoid potato chips and count calories at every single meal. Even if your workplace's cafeteria has reasonably sized portions, including small desserts, no one will stop you from buying two or three cookies.
To encourage healthy habits in an already structured workplace, companies could instead institute standing desks and hold standing or even "walking meetings," in which people move around while they discuss business instead of sit in a conference room. These interventions should, however, be tested scientifically before being widely promoted, Laibson said.
Government intervention is another way that self control could be imposed, but a controversial
one. The city of New York tried to limit sugary drinks sold to 16 ounces each last year, but an appeals court ruled in July that this was "arbitrary and capricious." In Laibson's view, such a policy needs scientific evidence that it has positive health outcomes before being broadly enacted.
But you don't necessarily need a boss or government official threatening to punish you for breaking rules you already want to follow for the sake of your health. You can set up a system in which you discipline yourself.
Through the Internet, you can wager your own money to commit yourself to your own diet and exercise aspirations.
A website called StickK allows you to put your own money on the line in support of whatever goal you may have; if you don't fulfill it, you lose the money. As Yale economist Dean Karlan, co-founder of StickK, told CNN in 2008, "It's a contract to make slothfulness more expensive."
So, think how much money your health-conscious self would offer your sweet-tooth self to keep the ice cream in the freezer, or not buy it at all.
Change can start today.