The way the brain processes attractiveness is by picking up ratio cues with the main one being waist/shoulder ratio (the infamous V shape) with 0.6 being statistically the most aesthetically pleasing to women...just as men respond to hip/waist/breast ratios.

So yeah a low body fat percentage creates a small enough waist to achieve this ratio. Note that bf% also associated with the visibility of the abs, which is also why women are biologically hardwired to like a six pack.

All being said, great for the beach etc. but in a club where every dude has a top on, waist/shoulder ratio become concealed and women will pick up on other visual cues that will usually benefit the more stocky rugby guys (despite higher bf%) than the smaller guy with incredible physique.

This is physical attractiveness only and no way determines the overall attractiveness of a guy to a woman.