He met Justus Liebig in Giessen and Lorenz Oken in Bern and began to form networks.

Liebig held that carbohydrates alone acted as fuel for the body while Moleschott included the roles of protein and fat.

[8] He lectured on physiology starting in 1847 and published Physiologie der Nahrungsmittel (1850) which received praise including from Alexander von Humboldt.

[10] The university under orders from the Interior Ministry of Baden reprimanded Moleschott for his radical political position, "brutal materialism" and atheism leading to his resignation in 1854.

[11] Next to Carl Vogt and Ludwig Büchner, Moleschott stood in the center of the public debates about materialism in Germany in the 1850s.

[12] Moleschott spent two years without an academic post and began to work on the 15-volume Untersuchungen zur Naturlehre des Menschen und der Thiere.

Another woman Mathilde Reichardt-Stromberg wrote an essay on morality through rational thought rather than religion using Moleschott's Kreislauf des Lebens.

[20] On June 9, 1889 he gave a public talk on the inauguration of a statue of Giordano Bruno in the Vatican alongside a speech by Gaetano Trezza (1828–1892).

A bronze bust by Ettore Ferrari was installed in the University of Turin on June 9, 1893, with a commemorative speech by Cesare Lombroso who had translated Moleschott's Kreislauf des Lebens into Italian.

His major works include: The Jacob Moleschott archive is held in the Archiginnasio of Bologna's public library.