Also from Scientific American:
Food craving, defined as an intense desire to eat a specific foodstuff, is a common occurrence across all cultures and societies. These yearnings, and those associated with nonfoodstuffs such as pagophagia (the practice of consuming ice) and geophagia (literally earth-eating), are not linked to any obvious nutrient insufficiency. In some individuals food cravings and dietary restriction may be related; however, these observations are inconsistent with the majority of published studies.
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