Hiding temptations in dieting backed by brain scans

Avoiding temptation works better than relying on willpower alone, a study of brain activity finds.

Experiment could offer way to explore drug abstinence, dieting, saving

Avoiding temptation works better than relying on willpower alone, a study of brain activity finds.

"Struggles with self-control pervade daily life and characterize an array of dysfunctional behaviours, including addiction, overeating, overspending and procrastination," Molly Crockett, a postdoctoral fellow at University College London, and her co-authors said in today's issue of the journal Neuron.

Giving in to a sweet tooth is one manifestation of struggles with self-control. (Toby Melville/Reuters)

"Our research suggests that the most effective way to beat temptations is to avoid facing them in the first place," she said in a release.

In the experiment, researchers studied 58 healthy heterosexual males in Cambridge and 20 in Amsterdam. Investigators used functional MRI as part of the study of self-control to explore the neural mechanisms involved.

At the beginning of the trial, participants were shown a series of 400 images of women in lingerie or swimwear and were asked to rank them on a scale of zero to 10 on how enjoyable they were. Each man's preferences were then used to present small, short-term rewards or a large reward after a delay.

Small rewards were mildly enjoyable erotic pictures and large rewards were extremely enjoyable ones. (The scientists said they could not use money, for example, since subjects could only reap the rewards of money once they left the lab. Food rewards like juice could interfere with the MRI readings.)

During some of the trials, the small reward was continuously available, and subjects had to exert willpower to resist choosing it until the large reward became available. Other times, the subjects could "precommit" — a self-control strategy that voluntarily restricts access to the temptation.

Promoting self-control

The short-term reward wasn't available during one of the phases to zero in on the brain region involved.

The researchers found that precommitment specifically activates the frontopolar cortex, a region that is involved in thinking about the future.

Since participants were also told that they could not finish the tasks more quickly by choosing short-term rewards, waiting always maximized the reward.

"We provide behavioural evidence demonstrating that precomitment is an effective strategy for promoting self-control," the study's authors concluded.

"Our new method for measuring willpower and precomitment in the same individuals offers promising new avenues for understanding the mechanisms underlying control failures in the context of drug abstinence, dieting, saving and studying."

The findings make sense to David Chilton, a former stockbroker and author of the personal finance book, The Wealthy Barber.

"I think it's interesting, the whole behavioural finance field in that they've come up with some incredibly creative ways to study human behaviour," Chilton said. "That said, most of their final observations are common sense."

"I've seen this kind of thing over and over again and it's why I push people to take less cash in their wallets and obviously not carry credit cards."

Chilton said the avoidance strategy doesn't work as well for food — like a candy bar — because it's a relatively low-cost item.

With files from CBC's Amina Zafar