Three co-defendants of the former Iraqi leader are also said to have refused some food over the past six days.
The group, which includes Saddam Hussein's half-brother, Barzan al-Tikriti, also boycotted court sessions this week in Baghdad.
Saddam Hussein and seven co-accused deny crimes against humanity.
The defendants say they were not responsible for the deaths of 148 Shia Muslim villagers following an assassination attempt on Saddam Hussein in 1982.
Saddam Hussein has embarked on hunger strikes several times over the course of his trial.
Khamis al-Obeidi's death sparked the latest protests
Fellow hunger strikers Barzan al-Tikriti, a former intelligence chief, and senior aide Taha Yassin Ramadan, are among those who boycotted court proceedings this week.
US military officials said that the strikers were had refused meals since 7 July, but were receiving medical attention and were drinking fluids with nutrients added.
"Saddam has participated in various hunger strikes during his detention, but his health has never been in danger," US spokesman Lt Col Keir-Kevin Curry said.
On Tuesday the chief judge in the trial, Raouf Abdel Rahman, adjourned the trial's closing statements until 24 July, and ordered all defendants to attend court or face an imposition of court-appointed lawyers.Last Mod: 20 Eylül 2018, 18:16