Education
He finished second in the marathon at the 1920 Summer Olympics in Antwerp, at 2:32:48.6, trailing Hannes Kolehmainen by 13 seconds, but beating the third-placed Valerio Arri by almost 4 minutes. At the 1924 Summer Olympics in Paris he was the flag bearer for Estonia and finished tenth in the marathon.
Career
Lossmann started as a football player for Merkur club before changing to athletics. Next year he set an Estonian record in one-hour running and competed in the Antwerpen marathon. Besides running, Lossmann worked for the Estonian Chocolate Factory Kawe in 1922-1936, and in the 1930s trained Estonian long-distance runners, but without much success.
In 1942-1944 he served as a sports administrator in Estonia.
During World World War II he fled to Sweden just before the arrival of the Soviet troops. Lossmann was earlier trained as a jeweler, and in Sweden he worked as a goldand silversmith.
In 1964 he made a silver cup for Gustaf VI Adolf of Sweden to express the gratitude of the Estonian community in Sweden.