How important is it for women to consume enough dietary fat?

Estrogen promotes muscle growth through various mechanisms [Enns & Tiidus 2010].
Therefore you may want to keep it as high as possible if you have physique goals (more on health later).

A long term study showed that dropping fat intake from 63 g (34% calorie intake) to 36 g (21% calorie intake) per day dropped estrogen by 13.9% [Boyd 1997].

Other well-designed research also supports that going from about 20% to 40% dietary fat may boost estrogen levels in women [Ingram 1987, Goldin 1994].

There is even more research showing the same, but often the women ate less calories in addition to less fat, which ‘polluted’ the outcomes.

All in all, research shows benefits up to 40% of calorie intake per day, which is about 80-100 g on a 2000 calorie diet.

Cool fact: one study observed that women who ate less fat decreased breast size [Boyd 1997 (2)]. Since smaller breasts are related to lower estrogen levels, this further supports that eating more fat increases estrogen.

On the flip side, higher estrogen levels are also linked to more risk of developing breast cancer [Russo 2006]. If this runs in your family, you may want to choose health over appearance: less fat on your plate to optimize your fate.