Magic System

One of my worlds has a magic system that allows people to produce any element, as well as a small number of molecules. When something is produced using magic, it spawns into existence in front of the user, replacing whatever was previously occupying that space.

Background Info

The molecules relevant to this question are: water, salt, and sugar. Water consists of H2O, salt consists of NaCl, and sugar consists of sucrose. Each material produced will be chemically pure, meaning the volume will consist only of whatever the produced molecule is. For example, magically produced water will have absolutely no dissolved solutes in it.

When consuming magically produced water, people will dissolve some sugar/salt into it until it becomes roughly isotonic. As this is set in a lower-tech world, they don't have the concept of tonicity, but will have learned over time that drinking pure water is unhealthy.

The Question

With that information in mind, roughly how long could a person survive on nothing but magically produced water, salt, and sugar? I imagine all sugar and salt will be dissolved in water before consumption.

Why I Am Asking

Knowing how long a person could survive on nothing but magically produced materials will have major worldbuilding implications. Could people make long treks with absolutely no supplies? Could soldiers on the battlefield survive off this diet for extended periods of time? Could there be entire cities of people living in barren wastelands, surviving off nothing but magic?

What I Am Looking for in an Answer

A high quality answer will provide an estimate of how long a person could survive on this diet, along with logical justifications using known biology and chemistry. While not necessary, further explanations of the kind of health effects such a diet would have would be helpful.

  • 4
    $\begingroup$ with no protein or nucleic acids it will be fairly quick, as the body litterally runs out of raw material. giving actual data for this will be hard as foods without wither these are very hard to come by so not much reason to study. $\endgroup$
    – John
    Aug 16, 2023 at 15:40
  • 14
    $\begingroup$ @Negdo no it really doesn't you, you lose about 30 grams a day of mass just from skin, hair, and intestinal lining loss. More importantly you have amino acid loss since we can't make several of them, once they are broken in a metabolic pathway they are gone. By your logic acute deficiencies cannot happen. $\endgroup$
    – John
    Aug 16, 2023 at 16:07
  • 1
    $\begingroup$ @John And now you are nit-picking... Recycling stuff efficiently doesn't mean a closed system.... Those 30 grams of mass contain some water and carbohydrates so in this question's case you loose less than 30 g of important matter. But even ignoring that it would take 100 days to loose 3 kg, which isn't all that much. And a human body don't tend to break down amino-acids if not needed. Cleavage of peptide bond is common, but degradation of amino-acids themselves... not that much. $\endgroup$
    – Negdo
    Aug 16, 2023 at 16:21
  • 14
    $\begingroup$ "Amino-acids are definitely not the limiting factor": Vitamins. Essential amino acids. Essential fatty acids. Calcium. No, the human body does not recycle more or less everything; we are great apes which evolved in a nutrient-rich environment, and our bodies are simply not made to work with just water and energy. $\endgroup$
    – AlexP
    Aug 16, 2023 at 16:35
  • 6
    $\begingroup$ Given that none of the molecules going in contain nitrogen, while urine leaving the body contains a considerable amount, I smell trouble. I'd also be very worried about the distinct lack of potassium. $\endgroup$
    – biziclop
    Aug 16, 2023 at 22:59

6 Answers 6


Warning: the links go to medical Wikipedia pages and they show bodies that look quite ill. Follow with caution.

Just isotonic sugar water will likely lead to death by scurvy, beriberi, and kwashiorkor, while also experiencing pellagra, likely before 10 weeks

Our magician gets a diet that is pretty much akin to (or rather: worse than) the Imperial Japanese Navy during the Meiji Era. Sailors in the IJN got a diet of tea and white rice for free, with no extra vitamins or sides. Any extra like greens required the sailors to pay for, and so most did not. The result of this one-sided food was a massive vitamin B1 deficiency, also known as beriberi - and in feeding sailors a more balanced food that contained unpolished rice and other grains, Takaki Kanehiro discovered vitamins in the first place.

The effects of a lack of vitamin C from fruit were known in the West much earlier, even if not understood. However, it was known that lack of fruit would lead to scurvy. Scurvy was particularly common among British sailors till fruit rations became a thing - partially due to how James Cook managed to get a world tour without scurvy after handing out lemon and lime juice.

The lack of vitamin B3 will result in pellagra. Pellagra is well known to be the result of too much corn-based food aid to Africa. The mage's very deficient diet does not provide this vitamin either. However, pellagra has a slower progression than beriberi or scurvy, so it is unlikely to be the actual killer, but it will add to the suffering of the mage.

The massive lack of protein however will result in one of the protein–energy malnutrition illnesses. As the basic calorie intake is covered, kwashiorkor is the most likely to hit the mage. Again, this illness is known to be a result of monotonous, carb-only food aid.

In fact, pretty much any micronutrient deficiency has a chance to show some of its ugly faces before the mage expires, all of them adding their own stamp to the painful martyrdom.

Survivability Estimation

It is remarkable how fast scurvy and beriberi can set in. First symptoms of scurvy on British ships tended to show up within a couple of weeks in weaker constitution sailors before fruit rations were given, and beriberi has a similar onset rate. More sturdy sailors might go about a month and a half before the symptoms show. Kwashiorkor will show itself as early as the end of week 2, but surely will be present in a quite pronounced way by week 6.

Without a more wholesome food, 2 months would be quite generous till the onset of serious symptoms, and at best I would give the mage about 10 weeks till they are unable to move from either or both illnesses and suffer from life-threatening complications. Two more weeks might be gained if the mage had a particularly good constitution before this diet.


Beriberi shows at first with fatigue, weakness, irritability, as well as tingling or numbness in the extremities. As symptoms worsen, muscle weakness and difficulty walking show as well as arrhythmic heartrate.

Scurvy shows at first with fatigue, weakness, irritability, and muscle aches. Its worsening symptoms include swollen and bleeding gums as well as joint pain.

Pellagra shows up with fatigue, weakness, and loss of appetite within a few weeks, combined with a sensitivity to sunlight. This skin condition worsens to a very red rash that is also scaling, and blistering, mimicking a non-healing sunburn. As already mentioned, compared to other vitamin deficiencies, pellagra goes on too slow to be the acute cause of death from this diet - but untreated it can result in confusion, irritability, cognitive impairment, depression, and a specific form of cognitive inability to remember called pellagrous dementia.

Kwashiorkor will show up with fatigue, weakness, and irritability as long as protein reserves last. When those stocks are out, muscles are cannibalized, leading to slimming arms and legs. Edema of the feet and belly start to form shortly after, and hair thins and starts to fall out. By the time of estimated death, the mage also is listless, irritable, and mentally apathetic.

Do note that other, more long-term deficiencies exist and were common among sailors. One example would be Iodine deficiency and its accompanying goiters. Those however only show up after months, at which point the mage already has succumbed.

Responsible Use

Limited Time

There's a general rule of three in first aid: Three minutes without air, three days without water, three weeks without food. The rule of thumb is, that at those points the body starts to cannibalize itself to a point that averse symptoms begin. It's clear that any caloric intake without any other sources of vitamins and protein could extend the starvation time, but there is only so much time that such a liquid-sugar diet could be used without the effects discussed above. That time I would pin as possible before other food needs to be provided to halt the downward spiral would be about 4 to 5 weeks. Such a fasting spree would still be a hard time for people, and clearly have a heavy toll.

Maybe the most comparable might be a Carthusian monk after Lenten fasting on a diet of vegetables, dry bread, and water in less than their normal quantities - though their insistence on veggies would manage to prevent almost all of the deficiencies explored above.

Fruits & Nuts + Magic

A small amount of real food, especially fruit and protein-rich nuts, could complement an almost-pure-magic diet to prevent deficiency illnesses, or at least delay their onset by as long as they are available, and thus extend the survivability.

Captain Cook famously gave every sailor a daily ration of 30 ml (1 oz) of lime or lemon juice and had not a single case of scurvy on his voyage. The RDA for Vitamin C suggests the equivalent of about 2 full lemons, which is roughly twice as much as Cook gave, but his sailors also had a somewhat varied diet with other sources of vitamin C than lime or lemon juice. Estimating from this, I would estimate that about two fruit and a small hand full of fatty and protein nuts per day would make enough complimentary food to make a full meal and skip on transporting carb-based food. However, do note that such a diet will not feel filling in the slightest.

For a more filling alternative, vegetables or other greens to complement the magic drink might manage to not only fill the stomach, but also prevent the symptoms of deficiencies fully.

  • $\begingroup$ These symptoms are quite similar to each other, not very specific initially, I guess. $\endgroup$
    – Mithoron
    Aug 17, 2023 at 13:48
  • 1
    $\begingroup$ This is a nice round up of what could possibly go wrong. Unless a person is very skinny at the beginning lack of energy is far from the first thing to cause problems that eventually lead to death. Al those other nutrients that the body needs must be replenished before the last fat reserves are depleted. So spawning in some sugar will only make you feel less hungry while dying. $\endgroup$ Aug 17, 2023 at 16:00
  • $\begingroup$ @MennovanLavieren As for feeling less hungry, maybe not. Ancient reports of people suffering fat deficiency include the want to keep eating, but no satisfaction upon doing so. $\endgroup$
    – user458
    Aug 17, 2023 at 16:22
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    $\begingroup$ It's worth noting that the molecules for vitamin B1, vitamin B3, and vitamin C are no more complicated than a sucrose molecule; so if the OP's mages can conjure up sucrose it would seem plausible that they could conjure up these molecules as well. How they would learn that these molecules were necessary in the first place is an interesting question, though. And I'm not sure what the simplest "protein" molecule would be that would stave off kwashiorkor. $\endgroup$ Aug 17, 2023 at 19:10
  • $\begingroup$ @MichaelSeifert I literally just tried to answer that problem with a frame challenge. There's too many issues with this in the first place. $\endgroup$
    – user458
    Aug 17, 2023 at 19:22

So called protein poisoning, which is really fat deficiency, is what will get you first. You'll start showing symptoms in a few weeks, particularly mental instability, and then death in about a month. The condition has been known since antiquity when people made a habit of eating only lean meat, usually rabbit, and none of the fatty organs like liver or brain. Hence the name, protein poisoning. There is a slight difference in what your character is doing, getting all calories from carbohydrates instead of protein, so this may look a little different in symptoms. The ultimate results I think would be the same though.

Not eating at all will kill your character at about the same rate.

This Dr on YouTube answers the question on why a carb only diet is very bad for you. He says some of what I say here, and more. If have to look into it more to be sure, but he indicates Thamine (B1) deficiency will get you first. That condition is called Beriberi. It is likely symptoms of multiple conditions will begin to manifest.

Soft frame challenge

In terms of worldbuilding, modern chemistry is not really that fun to consider when it comes to alchemy (traditionally understood as transmutation). For example, why can mages conjure NaCl and not any other salt, which includes much needed vital minerals? If those are included, what's the functional difference between those and bigger molecules? Only the size? It seems odd that a magic act of transmutation is limited by the molecule size in this one direction but not the other. For consistency you'd have to say that they can only convert from certain molecules, thereby severely limiting the application. Then there's also the question why they can have the deep and intuitive understanding of the chemistry of their alchemy, but can't use transmutation in combination with manufacturing to make virtually anything. If they can make NaCl, they can make just Na, presumably, a highly reactive element. They can make O2, and really make furnaces blaze. And so on. The possibilities are too empowering if alchemy works this way.

Instead, alchemy understood substances as consisting of base elements like water, air, fire, and earth, not H2O, NaCl, etc. Salt water is a combination of water and earth, but lacking completely in all other elements. Salt alone is a substance of earth only. And so on. Breaking down the magic limits would be more traditionally understood this way, instead of through the modern chemistry lens. So your limits here could be skill in transmuting earth like substance into other earth like substance, but you cannot transmute to fire, water, or air. You aren't limited to this Aristotelian model. You can invent your own or add to it. Whatever helps your story make sense. But this allows you to be vague in what actually happens in a transmutation, and gives you leeway in allowing or disallowing any particular outcome. It also keeps the ancient mystery of it, which is a widely enjoyed trope.

In this way, what a skilled mage actually needs to bring for a long journey and what he can conjure through alchemy is really up to your story needs.

  • 2
    $\begingroup$ protein poisoning requires a pure protein diet. As you can see in areas of Africa that were fed with pure corn for years during a lot of food aid, those people did not die from a very heavy carbohydrate diet. Suggar is carbohydrate. $\endgroup$
    – Trish
    Aug 17, 2023 at 7:43
  • 4
    $\begingroup$ @Trish Corn does contain fat. A few grams per ear. Sugar contains none. Also, I'm sure they ate other things at least occasionally. "Protein poisoning" as it is called is not an issue with protein intake. It is only called protein poisoning due to historical reasons. The issues one might have from too much protein in the diet are different and take longer to manifest. $\endgroup$
    – user458
    Aug 17, 2023 at 14:44

One to three months

For survival you need water, calories, vitamins, minerals, and amino-acids (source of nitrogen). In starvation the reason for death is usually the lack of calories, so the body starts to eat itself. After it runs out of fats, it starts degrading proteins, and without proteins cells cannot function. "Starvation ensues when the fat reserves are completely exhausted and protein is the only fuel source available to the body. Thus, after periods of starvation, the loss of body protein affects the function of important organs, and death results, even if there are still fat reserves left." So the first cause of death is preventable if you stop the body from using proteins as fuel - which you do by eating sugar.

There were cases where people didn't eat for more than a year. Sure, in that case the record holder did consume more minerals than just NaCl - not to mention some vitamins. But he DID show that it is possible to survive for a year with only minor intake of nitrogen. So nitrogen is not an issue.

You get all the water and calories from your magic, so that is not an issue. So the problem is your lack of vitamins and minerals. A human body is quite good at recycling both (and you DO get your NaCl, so that is something), and your gut bacteria will produce some vitamins. So the limiting factor will most likely be vitamin C as it is water soluble with relative large suggested daily intake.

Since we know that a person can survive 20 - 50 days without ANY food we can bet that having enough calories (and on top of that food for gut bacteria) your magic should achieve at least that. But probably not much more, as scurvy would be an issue - a leathal issue.

  • 4
    $\begingroup$ no one did not eat for a year, every time a claim like that is investigated it turns out to be a lie. the many you are talking about survived on a liquid diet, which definitely included protein. (he did not "eat" for a year. $\endgroup$
    – John
    Aug 16, 2023 at 15:41
  • 12
    $\begingroup$ @MS yes did you? "he consumed only vitamins, electrolytes, an unspecified amount of yeast (a source of all essential amino acids)... tea, coffee, and sparkling water, milk and sugar." like I said he had a liquid diet with many vitamins and nutrients it is useless for comparison $\endgroup$
    – John
    Aug 16, 2023 at 15:45
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    $\begingroup$ @Negdo Yeast and milk alone could completely supply your macro-nutrient needs, I suggest you learn a little bit about nutrients. Hell yeast was how you treated protein deficiency (pellegra) so he had plenty of nitrogen. plus is is taking vitamins so you can't even look at vitamin deficiency. $\endgroup$
    – John
    Aug 16, 2023 at 16:11
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    $\begingroup$ @John I would seriously reconsider your source of knowledge of nutrients if you believe that some milk in a tea is a significant intake of anything... And how much yeast he took is sadly unknow, but couldn't be that much if he went to toilet only every 50 days. Not to mention that with the amount of muscle he lost it is practically impossible that he reached his macro-nutrient needs. $\endgroup$
    – Negdo
    Aug 16, 2023 at 16:28
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    $\begingroup$ "unknown quantity of yeast" is not "minor intake of nitrogen", yeast can completely supply amino acid needs which is why it is used to treat protein deficiencies. again man survives 1 year on liquid diet is in no way useful for this. There are good parts to the is answer but this mistake just makes the whole thing false. $\endgroup$
    – John
    Aug 16, 2023 at 16:48

Depending on the person it can go from a few weeks to almost a year,

  • different people have different ammounts of bone to dissolve into calcium (calcium is used to reduce inflamation caused by sugar, proteins and various digestion related stuff)

  • different people have different ammounts of muscle in their body, the first days the muscles will cause you to consume more energy by simply existing, but after a while they will be canibalized by other cells in your body, so the more muscles you have the longer you are going to survive

  • A lot of vitamins are stored into fat tissue, some vitamins can't cause any overdose symtomps and the only thing that happens when you ingest 900 times the daily needed dose is that your fat will store all that extra vitamin and be consumed over the years... that's why it takes literal years to decades before someone dies of vitamin deficiencies like B12

There's also a thing humans have, it's called metabolism and hormonal self-regulation.

A reason many people find hard to lose weight even tho they train like horses.... is that for the majority of humans behaviour is flexible

if you are starved or incredibly tired because you ran a marathon and burnth 4000 kilocalories in a few hours ..... your body will start becoming less active, you will talk to yourself less, you will play with your pencils less.... shake your legs less, dream less , think less

and this can go on for weeks....so the 4000 kilocalories you burned by starving yourself thru diet or by running a marathon will be accounted for by weeks of living at an incredibly lower pace.

With this reasoning, many people in starvation reduce themselves to zombies so much so that their daily needs for proteins, minerals, calories and other vital stuff is reduced CONSIDERABLY

But most likelly your people are gonna faint and hurt themselves, and when you are this badly starved, hitting your chest on the ground can permanently stop your heart forever... hitting your head on a door that you didn't open because you had brain fog and didn't realize the door was closed... well it can send you into a coma.

Also there comes the problem of sleep deprivation, some people will not be able to sleep at all if they don't eat.

you won't feel tired, you won't feel the need to sleep, you will feel energized for hours as soon as you wake up, for people with anorexia it is very common to sleep 1-3 hours a day and feel refreshed.... Actually tiktok and instagram is filled with fitness gurus boasting about how they fast for weeks, sleep 1-3 hours per day and feel amazing because they defeated the matrix or something...

but this kills you.

whilist other people will do the opposite, will instead start to sleep more and more until they spend 24 hours in bed.

this later type of people survive longer.


Two important deficiencies will show up with this diet:

  1. As others have mentioned, protein.

  2. Fatty acids.

These will strike long before vitamin deficiencies matter.

  • 5
    $\begingroup$ Pretty sparse answer here. "These will strike long before...", how long? Why are fatty acids important, and what are the effects of deficiencies? $\endgroup$
    – CGCampbell
    Aug 17, 2023 at 10:21

Water and Salt

For short periods, you are better off without the sugar (salt and water only). Your body will go into Ketosis and then Atophogy. You need to be careful when you get below 10% body fat, as your body will start burning muscle which can cause serious (potentially long term) problems. The consensus seems to be that most healthy people can go 2 weeks on salt and water with no negative effects.

If you look into the research for this, you'll get flooded with the popularized "intermittent fasting" but that is totally different from what you are asking. Instead look for "long-term fasting" or "water fasting".

with Sugar

Adding the sugar will keep your metabolism going and you will essentially be on a sailors diet. In this case, you can go longer periods, but you will need to pack some kind of supplemental food: vegetables, nuts, dried meat. Pemican is a long lasting historical food that Native Americans used to get through the winter.

I can tell you from experience, a reduced caloric diet is much harder than a multi-day fast.


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