Loos joined the CSU Munich in 1982 and was a member of the executive board of the Junge Union in Bavaria from 1985 to 1986.

During the time of his studies he was involved in the university political student association Ring Christlich-Demokratischer Studenten in Bavaria.

Loos first became a member of the Bundestag after the 2017 German federal election winning the constituency of Munich North.

[3] On November 9, 2016, Loos was elected by the federal constituency delegates meeting of his party as a direct candidate.

He thus prevailed against the president of the Bund der Vertriebenen Bernd Fabritius, MdB, and thus succeeds Johannes Singhammer.