Oleg Shein and over 20 of his supporters have been on hunger strike for the past 28 days, since the mayoral electoral votes were counted.
He has lost 10 kilos already, and is facing heart problems, but has said he is generally in good spirits.
He won the vote in the polling stations with automatic counting machines, but lost where the ballots were counted by hand. In the subsequent weeks, he appealed to the election committee to investigate the alleged fraud, but got nowhere.
By Tuesday, news of his hunger strike had reached Vladimir Putin, president-elect. When asked what he thought of the protest, he simply said it was up to the courts, which prompted deputies from Shein's Just Russia party to walk out in protest.
Sue Turton reports from Astrakhan, Russia.
Source: Al Jazeera