Answer
His hunger strike can last for at most 91 days.
Work Step by Step
The energy content of fat is 33.1 MJ/kg, hence for 20kg of fat: 662 MJ
The basal metabolic rate is 72 Cal/h, which is 7.23 MJ/day.
So the fat energy can last for 91.50 days.
His hunger strike can last for at most 91 days.
