How did Bangladesh woman survive for so long?

In a miracle of sorts, a woman was pulled from the rubble of a collapsed building in Bangladesh on Friday—surviving for 17 days on dried food and bottled water that she’d found.

Would she have survived if she didn’t have those meager provisions? What’s the minimum a person needs to live on if trapped and waiting for rescue?

“My kids ask me this all the time,” said Dr. Joshua Kosowsky, clinical director of the emergency department at Brigham & Women’s Hospital.

Water, of course, is more important for short-term survival than food. A person in good health can survive for three to five days without water, according to Kosowsky, and about two to three weeks without food.

“I couldn’t imagine that this woman would have been able to bang on a pipe and call for help if she hadn’t had any food for that long,” he said. Her body would have started consuming muscles and vital organs to stay alive, and she likely would have been too weak to move.

Fortunately, the Bangladesh survivor, Reshma Begum, also had adequate water, which is vital to keep the kidneys from shutting down; when that happens due to severe dehydration, toxins quickly build up in the body causing multiple organ failure.

In terms of food, the human body can survive on about 500 calories a day for extended periods of time, Kosowsky said.

Begum was also lucky to have sustained no apparent life-threatening injuries when the building first collapsed and that she had adequate oxygen in the room where she stayed,

“If it had been sealed with no air flow,” Kosowsky said, “she couldn’t have stayed alive for long.”