Hunger was a much bigger killer of prisoners under the regime of Chadian ex-dictator Hissene Habre than torture, his war crimes tribunal in Senegal heard on Friday.
The 72-year-old, who fled to Dakar after being deposed in 1990, is being prosecuted in his adoptive country for war crimes, crimes against humanity and torture during his eight years in power.
Torture among an estimated 40,000 killed by the regime has been well documented, but Habre's tribunal heard that most who died in his notorious jails simply weren't fed enough to survive.
Rights consultant Mike Dottridge, stationed in Chad for Amnesty International between 1977 and 1995, likened conditions for prisoners with the repression of dissent in post-independence Guinea.
Some 50,000 people are believed to have been killed in Conakry's concentration camps under the iron rule of Sekou Toure from 1958 to 1984.
"Most of the (Chad) deaths were not related to torture but what is known in Guinea as the 'black diet' -- food and drinks deprivation and a lack of medical care... The amount of food was so small prisoners would die," Dottridge told the tribunal.
He went on to detail several forms of torture practised by Chad's feared secret police and prison guards during the Habre regime.
"The 'arbatachar' method has been well documented," he said, referring to a punishment in which prisoners have their arms and legs tied together behind their backs for long periods.
He also referred briefly to "the chopsticks method, with pieces of wood" sparing the tribunal details but explaining that "the blood flows from the nose of the victim".
"There was another method which required the victim to drink enormous amounts of water with chilli," he said.
In another technique, he said, "a pipe is put into the mouth of the victim and gas is introduced", while electric shocks were also widely used.
While the mistreatment of prisoners is largely undisputed, the Extraordinary African Chambers will rule on the extent of the abuse and whether Habre is personally responsible.
Once dubbed "Africa's Pinochet", Habre has been in custody in Senegal since his arrest in June 2013 at the home he shared in a plush neighbourhood of Dakar with his wife and children.
His trial heard earlier this week how Chad's Documentation and Security Directorate (DDS), described as "the eyes and the ears of the president", meted out a variety of abusive punishments to detainees.
Torture of suspects under the regime included electric shocks, gas sprayed into eyes, spice rubbed into their private parts and waterboarding, the tribunal heard.