Beautiful people have a lot going for them: They are more confident, make more money, and get promoted faster than their less attractive colleagues.

But for career-driven women, beauty is a no-win situation: The public wants you to be attractive, but, at the same time, not so beautiful that it's distracting.

This is the "beauty paradox" that women leaders face. They know that beauty matters, but are unsure of how much attention they should pay to their looks, says Vivian Diller, a psychologist and author of the book "Face It: What Women Really Feel as Their Looks Change and What to Do about It."

Take the recent outrage over Marissa Mayer's spread in Vogue's September issue. If she's playing dress up, she can't focus on running Yahoo, critics reasoned. But if Mayer didn't put any effort into her appearance, she'd just as quickly be accused of letting herself go.

Hillary Clinton is no stranger to this. When she ran for the presidential nomination, Rush Limbaugh asked on his radio show, "Do Americans want to watch a woman get older before their eyes?" And as Secretary of State, she was criticized as looking "tired and withdrawn" when a photo of her without makeup went viral.

People might say that looks shouldn't matter, "but in the real world, it does matter," Diller tells Business Insider. Yet ironically, "many people think that if these women care too much, then they can't care about the things that will make them a good leader, a good CEO, a good businesswoman," says Diller, who was a professional model and ballet dancer before becoming a psychologist.

The beauty paradox dates back to the "Women's Liberation" movement in the 1960s, when women rejected the idea that their physical appearance should play a role in their success.

"[These women] were very connected to the belief that the way to be successful was to maximize their other assets and minimize their looks," says Diller. But no matter how much we make ourselves believe that we can enter a man's world and fool everyone into thinking we're just one of the guys, this will never be the reality.

In the cave men days, the primary role of women was to attract a mate and procreate, says Diller. "It's hardwired into us that good looks and being attractive to others is an important part of our identity," she says.

Today, women have significantly expanded their roles beyond caretaker of the household. They earn more college degrees than men, and increasingly are becoming highly paid professionals, business owners, and breadwinners of their families. As women take on more public roles in society, one might think their appearance would become less relevant, but it remains a top factor in how they are viewed and view themselves.

To be sure, men are paid a premium for being attractive as well. The difference is that beauty has never been such a topic of conversation or determining factor for men's success as it can be for women, says Diller.

While a woman's worth is still greatly measured by how attractive she is, men typically define their own success based on power, money, and intelligence, says Diller. "This is the reason why men are admired for gray hair, but women aren't. Gray symbolizes wisdom, which has always been admired in men," she says. But that same gray hair will likely signify old age in women, and, unfortunately, our society has always defined female beauty as being synonymous with youth, says Diller.

However, Diller does say that appearance will play a bigger role for men in the future, as gender roles become increasingly ambiguous. "I think you'll see more men at hair salons and getting manicures and pedicures," she says.