This paper examines the effect of religious fasting on truth‐telling using a laboratory experiment in Egypt. While fasting‐induced religiosity may promote truth‐telling, the physiological and psychological changes during fasting, due to alimentary abstention and self‐control exertion, may reduce honesty, especially when fasting is augmented with effort. We examine this question by tracing individual truth‐telling decisions, in the absence and presence of additional effort, both before and during Ramadan. We find that neither effort nor fasting alone affects honesty, but exerting effort while fasting reduces honesty. We provide suggestive evidence on the mechanisms potentially driving this negative effect on honesty.

中文翻译：

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禁食与诚实：来自埃及的实验证据

本文通过埃及的实验室实验研究了宗教禁食对讲真话的影响。虽然禁食引起的宗教信仰可能会促进讲真话，但禁食期间由于禁食和自我控制的努力而产生的生理和心理变化可能会降低诚实度，尤其是当禁食因努力而增强时。我们通过追踪个人在斋月之前和期间是否做出额外努力的情况下说真话的决定来研究这个问题。我们发现，单独的努力和禁食都不会影响诚实，但禁食时努力会降低诚实。我们提供了有关可能对诚实产生负面影响的机制的提示性证据。