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The bitter truth about sugar and willpower: The limited evidential value of the glucose model of ego depletion.

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)1207-1214
JournalPsychological Science
Issue number9
Early online date11 Jul 2016
Publication statusPublished - 1 Sep 2016


King's Authors


Ego depletion is the idea that willpower draws on a limited mental resource, so that engaging in an act of self-control impairs self-control in subsequent tasks. To present ego-depletion as more than a convenient metaphor, Gailliot et al. (2007) have proposed that glucose is the limited resource that becomes depleted with self-control. However, there have been theoretical challenges to the glucose mechanism and the experiments that test it have found mixed results. We use a new meta-analytic tool, p-curve, to examine the reliability of the evidence from these experiments. We find that the effect sizes reported in this literature are possibly influenced by publication or reporting bias and that, even within studies yielding significant results, the evidential value of this research is weak. In light of these results, and pending further evidence, researchers and policy makers should refrain from drawing any conclusions about the role of glucose in self-control.

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