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The science of willpower

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Do you find it difficult to resist the temptation of that extra slice of cake, that next glass of wine, or that cigarette when you’re trying to quit smoking? If so, a taste of sugar may be all you need to stay strong.

A recent Curtin University study examining the science behind temptation shows that simply tasting glucose may boost willpower.

According to lead researcher Professor Martin Hagger from Curtin’s School of Psychology and Speech Pathology, ‘giving in’ requires considerable self-control or willpower, which drains the brain of energy.

“Scientists believe that self-control is a limited resource, a bit like a muscle,” Professor Hagger explained.

“A muscle needs strength to lift heavy weights but becomes fatigued after a period of time. Similarly, overcoming temptation requires willpower, which is thought to drain the brain of glucose, the fuel that powers the brain.”

This reduction in self-control ‘strength’ has already been demonstrated in many laboratory experiments: when subjects completed a task that drained their self-control strength, they performed significantly worse on a second self-control task. However, drinking a glucose drink boosted willpower and led participants to perform better on the task.

The Curtin study has taken this research to a new level, demonstrating that merely ‘tasting’, but not swallowing, glucose has the same effect.

“We found that simply rinsing the mouth for 10 seconds with a glucose solution had the same positive effect on self-control as swallowing the glucose solution,” Professor Hagger said.

“These results suggest that it is the perception of glucose – rather than its metabolism in the body – that boosts people’s willpower when fighting temptations.

”Only the glucose solution boosted willpower; an artificially-sweetened solution had no effect.”

The researchers believe that there are receptor cells in the mouth sensitive only to sugar that send signals to the brain. These signals activate areas of the brain associated with motivation and the need for control, two processes that are very important for self-control.

They further believe that tasting glucose, perhaps by rinsing the mouth with a sugary drink, sucking a sugary sweet, or chewing sugar-infused gum, may boost willpower. The research was recently published in the Personality and Social Psychology Bulletin at the following link:

Professor Martin Hagger PhD. School of Psychology and Speech Pathology, Health Sciences Curtin University Tel: 08 92662215     Email:

Hillary Lambert, Public Relations, Curtin University
Tel: 08 9266 9085, Email:       Web:

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