The Short Version
The evidence does not support underweight status as a cause of hyperandrogenism in women. Authoritative endocrine sources instead link underweight states such as functional hypothalamic amenorrhea and anorexia nervosa to low or normal androgen levels, while excess androgens are more commonly driven by PCOS, adrenal disorders, obesity, and insulin resistance. Rare lean-PCOS or atypical cases do not make underweight itself the cause.