Are you following bad advice? No sooner do we get with a program than the rules seem to change. Here, Cosmo takes a look at the most recent reversals of conventional wisdom. (News Controversy).(brief notes)

* If you haven't heard about the miracles of soy, the only explanation is that you've been living on another planet for the past few years. Believing that this little bean can prevent breast cancer, lower cholesterol, and build bones, women everywhere have been gorging on the stuff. (Edamame overdose, anyone?)

Well, here's a surprising news flash: Soy isn't necessarily a wonder food. Lorrainne Fitzpatrick, an endocrinologist at the Mayo Clinic, recently concluded that the studies that showed soy helps prevent bone loss were flawed. But the biggest shocker: There are indications that the isoflavones in soy may put women at risk for breast cancer, especially if you're genetically predisposed to the disease. "The problem with many medical studies is that there's a bias built into them," says Dr. Fitzpatrick. "So the findings can look solid, but when you do a more balanced trial, the outcome is different." As a result, we're constantly being bombarded with in formation that may ultimately prove to be wrong.

To demonstrate how drastic these swings in conventional wisdom can be, Cosmo has dug up a few of the most recently debunked theories. (Mea culpa: We've fallen for some of them too, but we'll do our best not to get fooled again!)

there's a man shortage

Actually, there used to be a man shortage, but the demographic tide has shifted, and now single women in their 30s and 40s have a surplus of eligible bachelors to choose from, according to the 2000 United States Census. Listen: Can you hear the sound of a man's biological clock ticking?

warm milk will help you fall asleep

"There isn't enough tryptophan (an amino acid that is metabolized into sleep-regulating chemicals) in a glass of milk to aid in putting you out," says Phyllis Zee, M.D., Ph.D., director of the Sleep Disorders Center at Northwestern University in Evanston, Illinois. What likely makes us drowsy is the comforting feeling that reminds us of childhood, explains Dr. Zee.