Doctors should be wary of how they talk to patients about their weight, say Yale researchers.

The study, from the Rudd Center for Food Policy and Obesity at Yale, found that parents prefer that health professionals describe a patient’s weight as “unhealthy” instead of using the terms “fat,” “obese” or “extremely obese.” The findings, published Sept. 26 in the medical journal Pediatrics, said parents feel that the latter terms stigmatize children rather than motivating them to lose weight. Pediatricians interviewed said they agreed with the findings and would be more careful in their word choice when conversing with patients.

“It is important to recognize that the language providers use in conversations about weight has potentially serious implications,” said Rebecca Puhl, lead author of the study and director of Research and Weight Stigma Initiatives at the Rudd Center. “Sometimes positive intentions can be expressed in ways that unintentionally provide fear and bias.”

A national sample of 445 parents with children ages 2 to 18 was surveyed online using Survey Sampling International. The survey asked parents to rate phrases such as “extremely obese,” “high BMI,” and “chubby” in terms of how blaming or motivating they found each description. The survey found that when parents believe a physician has stigmatized the weight of their child, 35 percent seek a new provider and 24 percent avoid further medical appointments.

Since doctors play a key role in discussions of health and weight, they should take care to make patients feel comfortable, Puhl said.

“Especially in primary care, it is important to build good relationships with families,” Katie Linnemann, a primary care pediatrician in the Mayo Clinic health system in Iowa, said. “And it helps to know what turns off or offends parents and what helps keep the door open.”

Linnemann added that though she is sensitive to negative weight terminology, she was surprised that the term “obese” has a stigmatizing effect because it is a medical term based on a patient’s body mass index.

Susan Woolford, pediatrician and medical director of the Pediatric Comprehensive Weight Management Center at the University of Michigan, said doctors continue to debate which weight-based terms are acceptable. The Center for Disease Control’s weight guidelines for children did not always contain the word “obese,” but were recently changed to be consistent with adult patient terminology.

A patient with a body mass index above the 95th percentile is considered obese.