The strikes are intended to pressure officials into ending the isolation of Abdullah Ocalan, the leader of the outlawed Kurdistan Workers Party, Hurriyet Daily News reported Saturday.
Ocalan is serving a life sentence on Imralı Island in the Marmara Sea. His attorneys have not been able to meet with him for 15 months.
Strikers also want an end to the ban on the use of the Kurdish language in legal proceedings and in schools.
"We cannot bear the conscientious and ethical responsibility of waiting while people are under life-threatening situations," Gultan Kısanak, co-chair of the Peace and Democracy Party said Friday.
Seven BDP lawmakers were to start a hunger strike Saturday. Party co-chairman Selahattin Demirtas was likely to join the strike, party sources said.
BDP lawmakers Emine Ayna and Ozdal Ucer joined the hunger strike Thursday.
Turkish Justice Minister Sadullah Ergin said Thursday a proposal for allowing the use of mother tongues in court would be sent to Parliament as soon as Prime Minister Recep Tayyip Erdogan returned from abroad.
Erdogan has described the hunger strike as "showing off," Kisanak said.