IN June 2013, millions of Americans contracted a disease. They developed it not because of some pathogen or illness, but thanks to the American Medical Association’s decision to label obesity a “multi-metabolic and hormonal disease state.”

On its surface, this seemed like a good move: Calling obesity a disease provides a clear warning of the significant health risks associated with excessive weight. And the obesity-is-a-disease message sparked attention, funding and research aimed at finding medically driven remedies.

We wondered, however, if there also might be psychological ramifications inherent in that message. Would it reduce or add to the burden of body-image concerns and shame? Would it empower people to fight back, or lead to a fatalistic acceptance of being overweight?

We suspected that, while there might be some benefits, the message that obesity is a disease might also have important psychological costs. In collaboration with our colleague Lisa Auster-Gussman from the University of Minnesota, we tested that hypothesis in three studies of more than 700 people, the results of which recently appeared in the journal Psychological Science.