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An Australian scientist believes sugar has been unfairly blamed for a person's self-control issues.

Macquarie University's Neil Levy says he is not convinced that self-control is "a depletable resource", as he explains in the journal Philosophical Psychology.

The current ‘ego depletion’ model, which links glucose and self-control, holds that glucose is the "fuel" for the engine of self-control.

Glucose isn’t a fuel to support self-control, he suggests, but a signal of environmental quality.

"A resource-poor environment is one in which it is relatively urgent to pursue shorter-sooner rewards, while a resource-rich environment is one in which there is little urgency,” he said.

“[Glucose] is a signal that the environment is such that there is relatively less urgency to pursue [smaller-sooner] rewards, and that strategies aimed at securing [larger-later] rewards are likely to be relatively more successful.”

As Levy explained, when people in a resource-rich environment are less sensitive to ‘competing rewards’, they tend to work longer at tasks for which the payoff or reward is delayed: the very definition of self-control.

Despite his commitment to his theory, Levy acknowledged that glucose might only be one signal of environmental richness.

“Any cue that signals a lack of urgency to pursue an immediate reward should be expected to have the same effect,” he said.

"It’s also unlikely that sensing glucose alone would be enough for the body to change its strategy.

"It may be that the body picks up on glucose only when other signals of poverty, conflict or instability are absent.

“It is not glucose per se that constitutes the signal: it is glucose correlated with the absence of cues indicating the need to pursue it immediately."

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