Review of the book "Crazy U" about the insane college application process (I've been through it twice recently) includes this about the gender imbalances:
Matters have been complicated in recent years by the success of girls, who persist in outperforming boys academically in high school and outnumbering them in college. But a university may admit so many girls that a tipping point is reached, making boys even less likely to apply or, as Mr. Ferguson notes, "attracting the wrong kind of boys for the wrong reasons."
Admissions officers have tried to rectify this problem by making schools more appealing to male applicants, expanding math and science departments, adding sports--and lowering admission standards for males, most of whom are white. Asian boys generally don't need any such help. "After several generations of vicious racism," Mr. Ferguson says, "followed by protest marches, civil rights lawsuits, accusations of bigotry, appeals to color-blindness, feminism, and eloquent invocations of the meritocratic ideal, the latest admissions trend in American higher education is affirmative action for white men. Just like the old days."