Douwes has a background in Kickboxing / Muay Thai. He began training under Hans Nijman, Dick Vrij and Gilbert Ballentine at 'Team Spirit Beverwijk', and would later on branch out to the notorious 'Mike's Gym' under the famed Mike Passenier. 

He has taken on some of the greatest heavyweight strikers of a generation, earning victories over Rico Verhoeven, Jamal Ben Saddik, the brothers Dževad Poturak and Dženan Poturak, Hesdy Gerges,  Mighty Mo Siliga, James McSweeney, Alain Nglaini, Jahfarr Wilnis, Aziz Jahjah and many others, while also being handed defeats by the likes of Pavel Zhuravlev, Cătălin Moraşanu,  Daniel Ghiţă, Saulo Cavalari, Anderson "Braddock" Silva, Rodney Glunder, Guto Inocente and Konstantin Gluhov. 

Competing over the years he has compiled a record of 66 - 25 with 19 wins by ko/tko, and has fought for the premier full-striking promotions including "Glory Kickboxing", "K1", "It's Showtime!", "Enfusion Kickboxing" and "SuperKombat". 

 
Although he has very limited success under full MMA rules contests, Douwes competed in the 'Ganryujima 1' hybrid event where he found great success. The tournament format and theme is of a throw-back to the classical days of martial arts and MMA where each style was pitted against the other in a battle to see which is the superior individual combat style. Representing Kickboxing, he was joined by 8 rivals who represented styles including Judo ( Kano Jiu-Jitsu), Karate, Capoeira, Sumo, Russian-Sambo, Shui Jiao and Senegalese-Folkstyle Wrestling. Douwes faced the Sumo, Sambo and Shui Jiao representitives, knocking each opponent out to be crowned the inaugral Ganryujima Champion.  

 
Some of Brian's achievements include ;

• 2017 A1 WCC Heawyweight Qualification Tournament Runner Up
• 2017 WFL Light Heavyweight Tournament Champion
• 2014 W.F.C.A. European K1 Super Heavyweight Champion +95 kg
• 2009 The Challenger tournament champion
• 2008 Planet Battle tournament finalist
• 2008 K-1 World GP in Amsterdam semi finalist