The American Medical Association has officially recognized obesity as a disease, a move that could induce physicians to pay more attention to the condition and spur more insurers to pay for treatments.

In making the decision, delegates at the association’s annual meeting in Chicago overrode a recommendation against doing so by a committee that had studied the matter.

“Recognizing obesity as a disease will help change the way the medical community tackles this complex issue that affects approximately one in three Americans,” Dr. Patrice Harris, a member of the association’s board, said in a statement. She suggested the new definition would help in the fight against Type 2 diabetes and heart disease, which are linked to obesity.

To some extent, the question of whether obesity is a disease or not is a semantic one, since there is not even a universally agreed upon definition of what constitutes a disease. And the A.M.A.’s decision has no legal authority.