Around 840 Palestinians are currently on the hunger strike which began April 17, according to the Israeli Prisons Service.
Led by Palestinian leader and prominent prisoner Marwan Barghouti, around 840 Palestinians are currently on the hunger strike which began April 17, according to the Israeli Prisons Service.
Palestinian officials have put the number at more than 1,000, with protests in Gaza and the occupied West Bank in support of them.
AFP spoke to Zeratzion Hishal from the International Committee for the Red Cross (ICRC), one of the few foreigners granted access to the striking prisoners as part of the organisation's monitoring of conditions in Israeli jails.
The Eritrean-Dutch doctor has visited a number of previous strikers and explained what happens physiologically to people consuming only water and some salt.
His version was verified to AFP by another doctor specialised in the topic.
Strikers only actually feel intense hunger for two to three days, Hishal said.
During those days, the body desperately searches for food, leading to sharp stomach pains.
"But after three days there is no food coming in. The stomach says there is no food and the brain accepts it," he explained to AFP.
"Most of the time (the stomach pain) would go because it is expecting nothing."
Instead of searching for new food, the body begins eating reserves of fat inside itself.
After more than a month, having consumed all fat reserves, the body starts eating its own proteins -- meaning muscle and later even organs.
The body tries to spare the brain, liver, kidney and heart.
"On a hunger strike, you eat yourself," Hishal said.
In the first two weeks, hormonal changes can make strikers strangely serene, even happy, Hishal said.
"Usually the people are euphoric, happy, because of the hormonal changes -- when you talk to them they are in good spirits.
"They don't feel a lot of pain. That comes later."
After two weeks, strikers start to experience dizziness, joint pain across the body and headaches.
Their hormonal imbalances shift again and they become quieter and sullen.
In the third or fourth week, strikers typically vomit uncontrollably several times a day for three to four days, due in large part to their body's natural balance deteriorating.
"Every time they drink they can vomit.
"They are tired and they become apathetic. They want to sleep and they don't want to talk much," he explained. "You see some depression."
Sleep is actually rare -- often only a couple of hours per night as strikers continue.
"The whole day they are lying on their beds. If you are lying then the brain says you have been sleeping and during the night they sleep two, three, four hours."
The intense joint pain involved in even tiny movements also makes it harder to sleep, he added.
"The sleep doesn't come," he explained. "Every day they sleep less."
After losing 10 percent of their body weight, which comes any time from three weeks in, strikers need to have regular medical checkups, Hishal said.
But it is around 30 days, the point at which the Palestinians are currently, that the risks increase significantly.
Around this point strikers have often lost between 18 and 20 percent of their body weight, meaning they should be hospitalised.
This could present Israel with a logistical challenge of hundreds of Palestinian prisoners in their hospitals.
Israeli law permits force-feeding of strikers whose lives are in danger, though the country's medical bodies have rejected it.
After around 50 days the risks become acute.
Strikers feel intense dizziness, suffer from uncontrolled eye movement and their heartbeats can slow.
Urine can be deep brown, or in some cases stop altogether -- indicating potential kidney failure.
Strikers will typically have lost around 30 percent of their body weight. Muscle erosion is so acute they can no longer support their skeletons, making standing impossible.
"From then on we expect serious complications such as organ failure and even death," Hishal explained.
Death is usually the result of cardiac arrest, but the exact timing is impossible to predict.
Ten Irish Republican hunger strikers, led by Bobby Sands, starved themselves to death in British jails in 1981, with their deaths ranging from 46 to 73 days.
"Bobby Sands' (group) shows how different our bodies are physiologically," Hishal said.
"But as the days increase the serious complications increase exponentially and death is expected at some point."