I recently received a comment from a reader, asking for my advice on how to deal with her younger sister's struggles with body image. "We tell her how pretty she is and how she isn't fat and we even work out with her when she wants to work out," the reader wrote. "But when we work out, all she says is how she's ‘too fat to do this' and makes a joke out of it."

I can relate. Self-deprecation -- putting yourself down and making a running joke of yourself -- is common among girls and women who don't feel good about their bodies. It was the example my mother set for me. Her theory: "If I say it first, it won't hurt so much when other people say it."

That's all fine and well, in theory. But the reality is that when we constantly put ourselves down, we're the ones who start to believe it.

As for advice, I have to offer my standard disclaimer that I'm not a doctor or a therapist, and that anything I say is strictly my personal opinion. You should always consult with a doctor or therapist for guidance. But I'll share some of my own experience in dealing with this kind of situation.

When someone I care about puts herself down, I take a deep breath and ask, "What makes you say that?" Then, I listen. Sometimes, self-deprecation simply becomes a bad habit. Put-downs and jokes fly out of the person's mouth before she even has a chance to think about what she's saying. Like any habit, it can be changed with time and effort. Try saying, "Do you realize how often you put yourself down? It hurts me to hear you talk about yourself like that. Every time you put yourself down in my presence, I'm going to say, ‘Stop talking about my friend like that.'"