I have a theory and it has historical proof as well.
During times of economic and food hardship a way to social signal that you have abundance is to get fat. Ever since the civil war Somalis have fallen under severe hardship and has then changed their beauty standards in suit this is why prior to the civil war where things were more normal the beauty standard was much more normal.
However in the west where food is more than abundant a thinner beauty standard exists because it shows restraint and moral character.
This trend looks like to exist throughout time.
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