Muscularity is the strongest predictor of mating success for men.
I absolutely believe this, having seen the drastic difference of how many women are interested in me randomly in public now that I am pretty jacked. Noticed this when I was in the army, too.
In three years, it went from basically no women looking at me or making eyes at me in public to it happening every time I go out. The only difference is that I gained 20+ pounds of muscle on a 5โ8โณ frame (and replaced some fat with muscle).