The self-supported FKT record holder for the Berliner Höhenweg is Italian trail runner Daniel Jung . He ran the loop on 13.08.2017 in 18h 11min.
Witness: Peter Fankhauser. Peter ran with Daniel the first 30min out of Mayrhofen and accompanied him also on the last kilometers when entering Mayrhofen again.
Daniel documented the loop via his watch (Movescount move: www.movescount.com/de/moves/move171762742?heatmap). He had no crew on the trail. He had his supply in his backpack and bought food in the mountain huts.
Loop Overview: www.tyrol.com/things-to-do/sports/hiking/hiking-tours/a-berlin-high-trail
Facebook Page for FKT: www.facebook.com/FKT-Fastest-Known-Time-Berliner-H%C3%B6henweg-1778360612465981/