There aren't statistics on how many diagnostic errors are due to weight, but the data for the general population is disturbing enough. "Doctors make mistakes in diagnosing 10 to 15 percent of all patients, and in half of those cases it causes real harm," Groopman says. Based on anecdotal evidence -- patients who've told her that their doctors are often too quick to blame symptoms on weight -- Rebecca Puhl, Ph.D., director of Research and Weight Stigma Initiatives at the Rudd Center for Food Policy and Obesity at Yale University, suspects that being heavy could further increase the odds of being misdiagnosed.