I don't think I'd totally agree with that. I think there was a decade or three where both men and women alike started going for a less muscular look. Then early 90s or so the idea of a toned body being the ideal for both sexes gained popularity, prompted by research showing what was and wasn't healthy.  Fat's never been attractive. But I do think there's been some fluctuation in preferred type of slim. Between skinny slim and muscular slim. Probably in large part caused by labor saving devices and desk jobs taking their toll on both gender's muscles.