If you have calories in your blood, you should leave them in there to get used instead of taking them out and back in. You wouldn’t be adding usable energy, you already had it.

You have energy stored in fat and muscle, but your body already is going to try and consume those without all that added stress of eating yourself from the outside.

That would be akin to running a hose out of your car's gas tank and back in. You'd use some gas for the pumping and add none back in the process.

You can never, ever get a net gain from self cannibalism of any kind. Digesting takes energy, and you're also having to heal/replace whatever it is you're eating.

Besides, the amount of blood that will come from a pulled tooth isn't enough to do anything useful. You wouldn't even gain minutes from it if the source was external.

Something to consider is that your body relies on blood glucose as its primary energy source. During starvation, glucose levels are severely depleted. This triggers your body to start using stored fatty acids. All remaining glucose is reserved for the brain to use.

By removing blood from your body and moving it to your stomach, you're essentially moving that precious energy to an organ that can't as readily make it available to the tissues that need it.

Thanks to the thermic effect, it also takes energy to digest and metabolize food. You'd be expending extra energy to digest the blood that was already in your body, where it was perfectly content carrying usable energy where it was needed.

I thought you can't digest more than a little bit of blood because of the amount of iron in it. And you're likely to start vomiting.

And if you lose too much blood, it'll kill you much more quickly anyways.

And of course if you lose blood and have to replenish it... That takes a good amount of extra energy to produce all the blood cells etc. And digestion also costs energy.

It wouldn't delay your death. But it would make it more pleasant. You would most likely pass out from low blood pressure pretty quickly and then you wouldn't have to worry about starving any more.

I've read a story of a 3 year old that had to have his tonsils removed. The poor child didn't understand that it's not good to swallow so much blood, didn't know enough to tell his parents what was up, and he unfortunately passed away, with a belly full of blood ☹️