Human survival without eating

Question

In this question, the most "realistic" idea is to have the human have an oxygen tank strapped to his back and connected to his nose at all times (preferably through a mask of some sort). However, this has the problem of having to remove it to eat.

Probably this exists already and I'm not aware of it (hence the "reality-check" tag), but is there any way to remove from a human being its necessity to eat, like feeding him intravenously?

Edit: OK, let's change the question a bit: is there a way to, yet again, change the human being into remove the necessity to eat altogether?

Answer 1

Human beings require energy to operate. We are designed to obtain this energy by consuming food. Consuming food also provides us with water to enable various other processes, e.g. sweating, urination, and tearing. So to take away our need to eat, you'd have to provide a new source of energy and eliminate water disposal.

You'd essentially need to replace the eyes in total. Our eyes are designed to tear. It's just how they work. We might be able to get by without sweating, although we'd be much more sensitive to temperature. Similarly, you'd replace the kidneys with something that recycled waste nutrients. Unfortunately, this means that we'd have no way of eliminating infection or radiation poisoning. We'd have to be protected from both of those. Remember that we take in radiation continually on Earth and more in space, so eliminating that would not be easy.

At that level of modification, it would probably be easy enough to get rid of the breathing mask as well. So let's assume that we're not going to do that. What are our other options?

There was an episode of Star Trek Voyager where the crew is copied into new bodies that can breathe the local atmosphere. This seems much easier than modifying an existing body, as you don't have to maintain backwards compatibility. You can just copy a human's consciousness into a new body that is compatible with conditions on the aliens' planet.

An alternative to this would be to copy the consciousness into a mechanical body. The mechanical body wouldn't need to breathe or eat. It could just plug in or refuel. An extension of this might be to upload consciousness into a computer. It could interact via virtual reality. Note that any of these possibilities covers both breathing and eating.

If you don't want consciousness transfer, then either intravenous feeding or a separate compartment where the mask could be removed are the ways that we know how to handle this without modifying the human.

Answer 2

The easiest approach is similar to the oxygen tank approach, keep him eating normal human food, simply figure out a way to provide it for him in the alien enviroment. There is no reason a human can't take off an oxygen mask long enough to take a bite of a sandwich and put it on for instance. Any advanced civilization will likely be able to grow something compatible with his dietary needs much easier then changing those needs. If this is too low-tech though you can provide food/nutrients without going through the mouth.

You could assume a situation where they can't just remove an oxygen mask though. Perhaps the enviroment they are in is so hostile that being exposed to it at all is dangerous, think space suits that astronauts have. If someone has to wear that he may not be able to take it off to eat his sandwich.

The next less invasive approach would be to have their oxygen mask include a food dispensing item. Imagine one tube for water, one for food-paste. This approach would allow them to choose when they eat, and even eat different 'food'. Depending on level of comfort desired this could be made somewhat convenient.

If this approach was too complicated or not desirable enough the next logical approach would be a feeding tube which would provide nutrients constantly. The same 'tank' that provides oxygen could have a second smaller tank to provide nutrients. However, feeding tubes aren't entirely comfortable to have in, so aliens would probably prefer the less invasive feeding 'tube' that one can suck on when their hungry. However, with a little technological skill it would likely be possible to create a feeding tube that is less invasive then the ones we use, likely one that would not go through the throat/nostrils but through the abdomen.

However, there are other concerns with such a potential approach. This implies a life lived in a space suit which would NOT be very comfortable. Your body needs to breath, to bath, to be itched etc etc. People in hospital beds get all kids of sores simply from not being allowed to stand up, people with casts itch like crazy. If you were confined to a suit like this non-stop it would NOT be fun. I imagine there would be a severe psychological impact of being stuck in a suit like that as well, a sort of claustrophobia.

If your aliens truly wished to make someone comfortable they would likely provide a small controlled enviroment that emulated human/earth enviroment. A room where you can take off your suit, breath naturally, take a shower, and eat normal food. Thus all these other options would be more of a 'I can't get home right now and need food on the fly' approach rather then a long term one.

Answer 3

There already exist creatures that don't need to eat: namely, plants. With enough bioengineering, a more efficient form of chlorophyll could be developed (because normal chlorophyll is thoroughly insufficient), and synthetic chloroplasts could be implanted into the person's epidermis. This would also lessen the necessity to excrete water, and even to exhale, as both water and carbon dioxide are consumed in photosynthesis. Additionally, this does not necessitate any sort of special clothing; rather, just the opposite, which could be a problem. As long as the person has sufficient exposed skin and is near enough to a star to feel the sunlight, this could possibly work.