As measured in calories it did not triple. But malnutrition went down a lot. And reduced malnutrition was one of the causes of rising IQ and physical stature

As measured in calories it did not triple. But malnutrition went down a lot. And reduced malnutrition was one of the causes of rising IQ and physical stature over that time period. The actual progress in standards of living in the USA from 1930 to 1980 is hard to overstate.