I thought it was not possible to go more than 40 days without food.
Something about the body reaching a tipping point, a point of no return where even if you ate, you would not survive.
I tried finding information about it on the internet and could not find it.
Some of the guys in the Japanese POW camps my grandfather was in apparently died like that. I think quite a few of them struggled onward driven by the desire to taste freedom again before they died but it coincided with being able to eat “normally” for the first time in years. Granddad was around 84 pounds at liberation.
If your body has plenty of fat available to burn, why couldn’t you go beyond 40 days. I suspect you could go into an extended state of ketosis until there’s nothing left.
300 lbs of fat is a lot of energy to burn through.
scroll down to page 5
http://archives.chicagotribune.com/1966/07/12/#page/5/article/scot-eats-his-1-st-solid-food-in-392-days
Before and after photo
http://www.terapeak.com/worth/1966-wire-photo-angus-barbieri-s-photo-after-a-fast-like-dieting-cvw10011/351558456649/