Beauty' is a currency system like the gold standard. Like any economy, it is determined by politics, and in the modern age in the West is is the last, best belief system that keeps male dominance intact.

"A culture fixated on female thinness is not an obsession about female beauty, but an obsession about female obedience. Dieting is the most potent political sedative in women’s history; a quietly mad population is a tractable one."

Naomi Wolf