Why did Europeans call US troops doughboys during World War 1?

The term "doughboy" is believed to have originated in the United States before World War I, but it gained prominence during the war as European soldiers referred to American troops by this nickname. One theory suggests it was linked to the soldiers' white, dough-like uniforms or the flour used in their rations. Another possibility is that it derived from the large round buttons on their uniforms, resembling dumplings or "dough." Regardless of its origin, the term became a symbol of American soldiers' identity during the conflict.