Ignorance.
Ignorance also plays a factor in my opinion. Unless a girl grew up working out as a result of sports, i.e. soccer, softball, field hockey, it's unlikely she was active. Perhaps she did light running and stretching. However, we all know here that the body requires strenuous workouts via lifting, yoga, pilates, and weight-training to remain whole throughout life. MOST girls don't get this.
They see Chyna, the wrestler, and assume muscles = big, bulky thighs (something they hate), as well as push-ups, etc. Unless they have an instructor, friend, or mentor who guides them in properly deconstructing this mental image, then it's unlikely she'll get it.
On the flip side, most girls were born O.K. enough to garner sexual interest from men. They didn't have to work that hard, so they were able to snag a man without much effort. How many of those women do we know? Plenty. As a result of drinking, they come to find out how easy it is for their "apple bottoms" to be come "dump trucks."
I've met some gals who are workaholics in the gym, about 1 in 15 are. It's their life, but if they ever changed that slightly, they'd lose what they gained, because though their body was the result of strict exercise and dieting, it wasn't "part of their life" as men tend to make it. Women, in my estimation, use it as tool for competition amongst women, or to feel better when approaching men, at some point the allure of those goals wears off. Life sets in, and a woman will assume other responsibilities that would derail her. Men, on the other hand, tend to put lifting second to only working, or football, and will get up at 5 am to go, which won't disrupt their schedules much, even with the addition of a child, gf, or new responsibilities.
For most of my life I've been a strict eater, with periods of strong devotion to lifting based on the current state of my life. However, few girls I dated, regardless of looks, were influenced by my devotion. And ever fewer could careless about eating styles. That's not to say a good % don't exist, but if you want that, seek it. I wouldn't expect to change someone, because the likelihood is high they'd go back (i.e. smokers). Some of the foxes I've dated were born with it (result of chemicals in their meat and dairy products), hence why they don't always respect those who work for things because they have no concept of what true work is.
Good genetics + a good mental well-being is what it takes. If her mother blew up, then you rest assured w/out the services of a psychic, she will, too. One of my X's mother's was a size "0" upon her wedding. In only a few short years she made it to 13+ as the result of several healthy children. She passed on her propensity for large tits, as well as her propensity for weight retention. My X Gf looked curvy at 135, but if she got slightly off track due to booze or poor habits she could balloon quick. I wasn't too saddened when I 'dodged the marital bullet' after we split, since I *knew* the same would happen to her and I could already have purchased the necessary viagra now.
A-Unit