Feingold received a BS degree in 1921, and an MD in 1924, from the University of Pittsburgh, Pennsylvania.
Feingold worked as the house officer at the children's clinic of the University of Vienna, Austria from 1928 to 1929.
In 1951, he joined the Kaiser Foundation Hospital and Permanente Medical Group, and established all of the Departments of Allergy for Northern California.
From then until his death in 1982, he was Chief Emeritus, Department of Allergy, Kaiser Permanente Medical Center.
Although the diet was popular, scientific research found no good evidence that it was effective.