http://wilsondefense.blogspot.com/2010/02/some-hard-realities-of-reality-based.html

Not to sound Male chauvinist, but it is usually very difficult for a Woman to defend Herself against a Male unarmed. This is even the case with Women who have trained in unarmed defensive tactics & is even true in cases where the Woman and attacking Male are the same size(although unusual). The reason is that the physiology of Men & Woman differ greatly.If you take a 150 lb Man & an 150 lb Woman the obvious difference will be that the Man will have usually have a greater percentage of lean Muscle Mass at that weight then an equal weight Woman. He will also have heavier, denser bone compared to the Woman and his tendons & ligaments will be thicker & stronger therefore allowing his Muscles to generate more strength.
What is not visible is the difference in their nervous system.In early embryonic development,we all essentially start out as female until the Male fetus undergoes a staged flood of Testosterone which is the turning point in the Fetus becoming virilized and exhibit Masculine characteristics. The flood of androgenic hormones not only has effects on the outer superficial features, but also rewires the Brain & nervous system differently from the female. These changes give Men their greater natural ability at spatial distance & timing applications,general athletic abilities and stronger muscle function due to the Brain & nervous system sending out more efficient nerve transmissions.
My first job when I was 16 was at a grocery store & there was a masculine Women who worked as a Meat cutter who was a Bodybuilder/Power lifter.She definitely LOOKED strong as She was fairly tall for a Woman and exhibited a large amount of Muscle as well ans weighed in at about 135 lbs.I also worked with a young boy who weighed in at about 125 and was about the weakest High School kid I had ever around. At the company picnic,I got the idea of pitting Her(the strongest Woman I knew) against him(the weakest Male I knew) in an arm wrestling contest.They agreed to the contest and after several minutes of both exerting all they had,the contest was ruled a draw.
"ZAP" from the American Gladiators was once a contestant on a game show hosted by Bob Eubanks. Zap was a Female Bodybuilder and Power lifter had as much Muscle as any Woman I had seen.Bob Eubanks was a late Middle aged thin Man with no training experience.They arm-wrestled on the show for fun and Eubanks slammed Her.
Just two examples,but this is the norm.I've trained in Martial Arts for nearly 30 years and have come across many Women who were 3 rd degree Black Belts etc. or trained for many years & not one of them could mount any real effective offense in a live sparring drill against a normal Male. I remember sparring one 3rd degree Black Belt Woman Instructor who asked me to "get down on my knees" when we sparred.Is that reality? Would that do Her any good in learning to protect Herself? The answer is a resounding NO!