Ok_Ad_9188 OP t1_iyapvm9 wrote on November 30, 2022 at 12:19 AM

Reply to comment by nesquikchocolate in ELI5: Why can't you just not eat if you're overweight? by Ok_Ad_9188

Sure, but I'm not asking about it as a plan or practice exactly, I'm more curious about the...I dunno, mathematics? Like as I understand it, a human being consumes a certain amount of energies in the form of calories, they use that energy to function physically in a variety of ways, and any surplus they have is converted into fat and stored in the body, any deficit is covered by using those fat stores. I'm assuming I must be misinformed about that, because it seems like consuming zero calories would mean that all energy requirements would be drawn from fat stores, so as long as you still had fat stores and consumed the vitamins and minerals needed to fuel the numerous chemical reactions that a human does, you shouldn't be in any danger, but everywhere I look says that simply not eating is inherently bad for you and doesn't explain how Angus Barbieri was able to accomplish it

nesquikchocolate t1_iybr9zv wrote on November 30, 2022 at 5:22 AM

Your body weight is mostly water.

You drink a liter of water, you gain 1 kilogram of weight.

You urinate 1 liter, you lost 1 kilogram.

When you're starving, your body functions slow down significantly, meaning you start to retain the water that you drink, so you don't lose weight like that..

But you still need to drink water and urinate, else your blood becomes toxic!

Ok_Ad_9188 OP t1_iybt120 wrote on November 30, 2022 at 5:40 AM

Of course, but once again, you're talking about weight loss, I'm just asking about the human body storing and using calories. Ignore weight in this scenario, it's not a factor. What I'm trying to figure out is why you'd go into starvation mode at all. In this scenario, the subject is taking supplements, a wide array of vitamins, minerals, amino acids, and basic proteins, and they're drinking plenty of water. So they're not suffering from malnutrition or dehydration. They're also obese and have many pounds of fat storage (Barbieri weighed in at 207 kgs at the start of his fast) so they aren't deprived of caloric fuel; why would they go into starvation? Why would any bodily function slow down when it has all the water, nutritional needs and calories it has to perform them as well as it needs? And even if they did go into starvation, they still have to consume calories, and the calories they consume have to come from somewhere. Would the human body really just die of starvation while being completely dietary supplied and with an ample supply of calories still available to it?

nesquikchocolate t1_iybtwbk wrote on November 30, 2022 at 5:50 AM

Starvation is triggered by hormones, which are released because your stomach is telling your brain it's empty and ready for more. This starts 4-8 hours after your last meal, always. If you interrupt these hormones, like some diet pills did, then you get "magic" weight loss without feeling bad.

But now you're damaging the brain, telling it to ignore basic survival signals - and the brain doesn't run on glucose, so it cannot get fuel from body fat - it needs your liver to create ketones from fatty acids, and when you consume fatty acids, you're adding calories again, which will allow you to survive indefinitely.

Ok_Ad_9188 OP t1_iydttg1 wrote on November 30, 2022 at 5:40 PM

That makes sense. But it still doesn't explain the mysterious case of Mr. Barbieri lol I'm beginning to feel a certain amount of skepticism over the case now. Thanks for the input man

nesquikchocolate t1_iye8025 wrote on November 30, 2022 at 7:10 PM

Doctors can keep people alive in comas for decades, we've got plenty of proof for that.

If your goal is to be "alive", then sure, it can be done using supplements and your body fat reserves - we've also seen a few cases of this.

The amount of permanent damage you do to your organs and brain, however, is unknown. How the extreme starvation feelings will rewire your brain is unknown. How your body will react when you start eating again is largely unknown.

Unknown is scary for doctors, they avoid anything and everything that isn't in their handbooks - for good reason! People sue people on a whim.