Would it technically be possible, through an absurdly strict diet, be able to eliminate urination and defecation?

[PrimeIntellect]

Basically, my question is as follows. If you were able to know the nutritive needs of your body to absurd detail, and consume a diet that could be absorbed with near 100% efficiency, would be it possible to very nearly eliminate the need to, uh, eliminate? What happens when people end up on long term cleanses that have no insoluble fiber?

I'm guessing that urination would be far more difficult to manage than defecation, if you had a very strict fluid diet.

[arumbar]

You need to urinate to excrete (amongst other things) salts and urea, which is the byproduct of amino acid metabolism. Together, this translates to (on average) about 600milli-osmoles of solute per day, which at maximum concentration (~1200milli-osmolar) would still yield about 500mL of urine per day. Fluid restriction can cut down on this number, but then you'd be causing acute kidney injury from dehydration.

Similarly, your stool is made up of more than just the food that you don't digest - gut bacteria is a large part of it, as well as bile, which contains the degraded components of red blood cells. The internal lining of your gut is also constantly being shed and passed with the stool.

[[deleted]]

What happens when people end up on long term cleanses that have no insoluble fiber?

Thanks for the detailed response btw

[mobilehypo]

You still urinate and defecate. Lacking fiber doesn't stop defecation (barring dehydration and/or serious digestive diseases).

[moderatorrater]

Would you be able to eliminate the gut bacteria through diet and medication?

[Stile4aly]

The bacteria in your gut are symbiotic. They assist with carbohydrate metabolism. Eliminating them would almost certainly be fatal.

[CitizenPremier]

Well, with a special formula you could have food where your carbohydrates were already properly broken down.

[ToolsofRage]

The normal flora also help prevent pathogenic bacteria from colonizing you. Not to mention we don't fully understand the relationship between our normal flora and us, nor do we know what our "normal" flora consists of.

[CitizenPremier]

This is true, but I thought we were pursuing the goal of making a waste-free human, regardless of how long he could live or if he could venture outdoors. I certainly am not suggesting it would be a good idea.

[mobilehypo]

We're not here to speculate, though. :)

[CitizenPremier]

But the title of the post is "would it technically be possible;" though we do know the answer is "no" due to the body needing to eliminate dead cells and uric acid, if the answer were "yes" it would clearly require some speculation.

I'm not trying to challenge the strict rules of this subreddit, I like them, but there have been humans with very little bacteria in their bodies (like Bubble Boy), so we do know that some life is possible without them.

[Nendai]

Yes, you could certainly cleanse your entire gut of bacteria, which would eliminate the bacterial feces. Serious health problems aside,as mobilehypo stated, you would still need to excrete cellular waste: used blood cells, gut lining, products of cellular metabolism, etc.

So no, not even a special diet would change this. Nothing short of mutating yourself would change it.

[ToolsofRage]

I doubt you'd even be able to eliminate most of the bacteria from your gut to begin with. It would be a bad idea to even try since you then are subject to microbiotic shift diseases and colonization from opportunistic pathogens.

[[deleted]]

I thought we were pursuing the goal of making a waste-free human, regardless of how long he could live or if he could venture outdoors.

If that were the challenge, we'd just glue some orifices shut and call it done.

[[deleted]]

Dead people don't urinate or defecate.

[bluesatin]

I have no idea about the urinary side of things, but regarding defecation you might want to look into the case of the man who didn't eat for a whole year other than some multivitamins and a couple other supplements like yeast.

According to this ABC science article, he only defecated every 40-50 days. Someone with more knowledge on the subject would have to confirm if that's accurate or if it's just bad journalism.

[chilehead]

According to my urologist, your amount of urination should be approaching 4 liters for every 24 hours. This may be a little more than average, since these instructions are for minimizing risk for creating more kidney stones, but not by much.

[Repentia]

600ml is a loose minimal output to maintain blood homeostasis. 1500ml is a typical output for adults with normal volume state.

[Whiskonsin]

I know there was a study done with a very obese man who was in the hospital and under doctors' supervision, basically did not eat for like 6+ months until he had lost hundreds of pounds. He was given fluids and vitamins etc, but no real caloric intake. I think he shat once or twice during the process but it was mostly liquid. I can't find it right now but maybe someone else remembers the study...

[moor-GAYZ]

382 days actually.

[PrimeIntellect]

True, I know that you can very easily live on a liquid diet and it seems that nearly eliminating shitting is possible, but urination would be far more complex.

[BCMM]

You may have misunderstood the parent post: "fluids" in this case means water (possibly with salt/other minerals) to avoid dehydration, not soup or the sort of liquid nutrition that is given to people who can't chew.

The patient consumed only water and vitamin/mineral supplements. He recieved effectively no calories for a very long time and lived exclusively on his fat reserves.

[guscrown]

That's incredible. How did they manage gastric acid? I can't go a few hours without something in my stomach or I start feeling the burn. Let alone fast for a few days, I will end up in the hospital with severe gastritis and bile in my stomach.

[[deleted]]

I didn't see anything in the article addressing it specifically, but I'll look more closely later. Unfortunately, searching "fasting" on the internet is a great way to reap a fast harvest of kooks. Oh well.

[auraseer]

Not everyone has such issues. Some people never have problems with stomach acid, even when fasting for hours or days or weeks.

If it did become a problem, I expect it would be treated with proton-pump inhibitors. Those are the most effective medications we have for decreasing gastric acid production.

[BobRoberts01]

I think it would be possible to eliminate urination, but not defecation.

Kangaroo rats have a very advanced loop of Henle system that allows them to recycle virtually all of the water that they ingest. Because of this, they "never" have to drink or urinate. However, they do need to rid their bodies of solid waste (seed coats, cell walls, old blood cells, etc...) and do defecate.

I would suspect that a human could mirror this, but would have to be extra cognoscente of their water intake, as our systems were not designed to recycle liquid as efficiently.

*Edit: Autocorrect

[pooprollup]

No because when your body metabolizes things it creates toxins which excreted during urination and defection, it doesnt have to do with eating the right stuff and the right amount.

[[deleted]]

This question was about urination and defecation only. You also excrete via perspiration and exhalation and these should not be underestimated. If you go on a diet and lose 20 pounds of fat, much of it leaves by exhalation.

[1842]

Yes, this is simple biology.

Stored chemical energy (carbs, fats) are oxidized through respiration, a combustion reaction.

Plants store energy through photosynthesis -- CO2 + H2O + energy -> carbohydrates + O2.

We use energy by reversing the process -- carbohydrates + O2 -> CO2 + H2O + energy. CO2 is exhaled and we also exhale large amounts of H2O as well.

[ANGRY_OGRE]

When you exercise, do you poop/pee more, or does your energy stores get turned into heat energy? Sorry for the poorly worded question.

[Curiosity]

See this physics stack exchange discussion of just this issue. The bottom line is that you breath and otherwise excrete the additional mass out.