The claimEvidence A · guideline-tier
Willpower is a fuel tank that drains as you use it
The evidence
The ego-depletion model failed a 23-lab preregistered replication (d=0.04, Hagger 2016); design your environment, don't white-knuckle.
The mechanism, in brief
A very popular claim: willpower is like a fuel tank — every use drains it, so by evening you can't resist the snacks. This ego-depletion model does not hold up under rigorous testing.
Sources (1)
- Hagger, M. S., Chatzisarantis, N. L. D., et al. (2016). A multilab preregistered replication of the ego-depletion effect. Perspectives on Psychological Science, 11(4), 546-573. Across 23 labs (N = 2,141) the pooled ego-depletion effect was d = 0.04 (95% CI -0.07 to 0.14), not different from zero.