Gustav Piers Alexander von Bunge (19 January 1844, Dorpat – 5 November 1920, Basel) was a German physiologist known for work in the field of nutrition physiology.

At Dorpat, he had as instructors, Friedrich Bidder (1810–1894) and Carl Schmidt (1822–1894).

Among his more important studies were the interplay of potassium and sodium within the body; the association of sodium chloride with metabolism, and analytic studies of iron metabolism.

[1] He was the author of treatises on alcoholic spirits, of which he denounced as a "threat to health and heredity".

[2] His name is associated with "Bunge's rule", a nutritional law based on his research of human and animal milk – "that nutrients in milk are proportional to the growth of the offspring".