As a teenager growing up during years of war in the Western Balkans, Dijana Hrka learned to live with hunger. There was no food, no electricity and little water when her Serbian community went into hiding under enemy bombardment, but she survived.

Now Ms. Hrka, 48, is again without food — this time by choice.

She is two weeks into a hunger strike outside Serbia’s Parliament to avenge the deaths of 16 people, including her 27-year-old son, Stefan. They were crushed by a falling concrete canopy at a recently renovated train station in northern Serbia last November.

The disaster fueled public fury over government negligence and corruption, prompting some of the largest anti-government demonstrations in Serbia since the fall of the former dictator Slobodan Milosevic in 2000.

Before the canopy collapse, Ms. Hrka, a divorced mother of two and fast-food cook, had little interest or time for politics or protests against President Aleksandar Vucic, whose government, European Union officials have warned, is at risk of democratic backsliding.

But ever since the tragedy at the train station in the city of Novi Sad, Ms. Hrka has been such a constant presence at student-led demonstrations that she has become an unlikely symbol of a movement.

“I’m ready to die for this, I’m ready to live for this,” Ms. Hrka said last week, huddled in a tent that she and her supporters have set up outside the Parliament building in Belgrade, the Serbian capital. “I’m ready to do anything so that we will unify, and get rid of this evil.”

Nov. 1 was the anniversary of the Novi Sad disaster that killed her son. The following day, to highlight her and other protesters’ demands for justice for the victims and government accountability, she stopped eating.

“Since I have been hungry before, I think I can tolerate it more than maybe ordinary people,” Ms. Hrka said, who has continued to drink water, tea and juice.

“But then again,” she said, “you cannot tolerate it for so long — maybe 12 to 13 days before something will happen.”

During her strike, she has been kept awake by laser beams and blaring rock music aimed at her tent by counterprotesters who support Mr. Vucic. Their own encampment outside Parliament, which was set up months ago, is just yards away from her.

Serbia is a deeply divided country, riven by growing anger and distrust that is aggravated by disinformation. It is torn between wanting to join the European Union and holding onto a longtime alliance with Russia. Many Serbs are still bitter about NATO’s 1999 bombing campaign against Serbia for its aggressions in Kosovo, during years of conflict in the Western Balkans that followed the breakup of Yugoslavia.

Accusations and counter-accusations about money laundering, street beatings, and lying are routine political discourse, even at the highest levels of government.

Approval to build a luxury Trump hotel on the site of a bombed-out architectural landmark in Belgrade, pushed through Parliament this month, has increased suspicion of government corruption and galvanized protests.

In the disaster at the train station, Serbian prosecutors have charged at least 13 people, including two senior government officials, with corruption related to substandard renovations that were led by Chinese contractors.

But courts have yet to convict any of the suspects months after the charges were brought, stoking widespread fear that the victims’ deaths will go unpunished.

In the weeks after the train station disaster, Ms. Hrka said she was too stunned to react. But then, watching TV in her home in Belgrade, she saw how young people she regarded as mere “children” were in the streets demanding justice for the deaths.

“Suddenly, I just followed them onto the street,” Ms. Hrka said during one of four interviews with The New York Times last week in her tent. “And here I am again, out on the street.”

Her son, Stefan, was a maintenance worker at a company in Novi Sad when he was killed.

“We were very close, and we always wanted to look at things positively, because we were living in a difficult situation,” Ms. Hrka said. “He started working and he helped me so that I didn’t have to work so many jobs. We said to each other that we will always be happy with what we have, and we were.”

When she was younger, she wanted to be a beautician, and even during her hunger strike, her fingernails were polished in a shimmering rose color. “In the future, if all will be well with this,” she said, “I would like to make a foundation that will have Stefan’s name, and then that foundation will help all children.”

Well-wishers, including priests, have brought prayer books, flowers, religious icons and other gifts to her tent. But Ms. Hrka admitted that she saw no clear end to the protest. “I don’t know — whatever God says,” she said. “It’s in God’s hands.”

Ms. Hrka will not talk about her younger son for fear that he will be targeted by security services, but sees herself as a mother to the students who are leading the protests.

“If I have to die, so that all the children can live freely, and Serbia can be free, I’m ready,” she said.

If Ms. Hrka dies from the hunger strike, “it could be a tipping point” after a year of simmering but mostly peaceful protests, said Rasa Nedeljkov, program director of the Center for Research, Transparency and Accountability, a government watchdog agency in Belgrade.

Ms. Hrka and the other protesters are also calling for snap elections to replace Mr. Vucic, who has been in power as prime minister and then president since 2014. He shows no intention to step down.

In an hourlong interview in his office on Thursday, Mr. Vucic vowed to “show that justice exists in the country” and to hold accountable anyone responsible for malfeasance in the train station construction. But he said it was up to the courts, not him, to handle the investigations to avoid any appearance of government interference.

He also denied that security services are intimidating and arbitrarily detaining protesters, as E.U. officials have reported.

Mr. Vucic was careful to not criticize Ms. Hrka. But he suggested that she was being used as the latest pawn in years of protests by political opponents demanding his ouster. (Ms. Hrka said it was her decision alone to go on strike. “Nobody made me do this,” she said.)

“They were hoping that Dijana Hrka was going to die and then everybody will blame me,” Mr. Vucic said. “I do care about her,” he added. “I do worry about her, and they don’t.”

Mr. Vucic said he had called Ms. Hrka last week to try to convince her to eat again. Instead, the conversation further stoked their divisions.

Even officials who support Ms. Hrka have asked her to stop her strike.

“If she continues, this is like suicide,” said Dragan Djilas, an opposition leader in Parliament. “I am very sad about this.”

Others say they are inspired. Another anti-government protester and his teenage son started a hunger strike, although the boy has since resumed eating.

“Dijana is a mother who suffered a lot, and she wanted to be with the whole movement because she lost her child,” said Vladimir Stimac, a former professional basketball player who was recently detained by police for participating in the protests.

“I’m really concerned for her health, but none of us can take away her autonomy,” he said.

On the night of the 11th day of her hunger strike, Ms. Hrka was taken to a medical clinic by her supporters and treated for dehydration after she felt weak and her blood pressure dropped.

Several hundred supporters gathered outside her tent in a silent candlelight vigil that lasted at least 15 minutes. Then the crowd began chanting “Dijana Hrka” — a murmur that rose to a shout.

Ms. Hrka returned several hours later. The next morning in her tent, on the 12th day of the strike, she appeared gaunt and pale but sounded stronger than she had the day before.

She said she would not stop.

“The children look up to me,” she said. “When they started the protests, the police were trying to suffocate them, to suffocate the protests. But then with me, together, we are stronger.”

Alisa Dogramadzieva contributed reporting.