Well…
Since beer is liquid bread.
Quite a while, especially if you also had a multi vitamin..
I wanna see the Martian envisioned where instead of sustaining on pieces of potato, he drinks beer.
I also want to see more pirate-themed rants, preferably drunk.
Agreed. It's been common throughout history for people to live on only beer and water for a few weeks at a time.
I imagine you could survive at least a few months on doppelbock if you were in good health beforehand.
It probably would depend on what kind of beer. You could probably live a long time on just water and Guinness, but not very long at all on Natty Light. Either way I think you'd probably be pretty sick of beer within a week or less
Beer has very little salt. Sodium is essential for basically everything your body does. https://en.wikipedia.org/wiki/Hyponatremia
Youtube vid about a dude who consumed nothing but beer for 6 weeks. https://www.youtube.com/watch?v=mfrdKXEdPFU
It was said some monks would only drink beer during Lent as part of their fasting.
https://www.catholicnewsagency.com/news/35537/these-17th-century-monks-did-a-beer-fast-for-lent
There also is this man who raises charity money doing it as well https://www.cincinnati.com/story/entertainment/2021/02/10/ohio-beer-only-lent-fast-cincinnati-del-hall/6705238002/
Hmmm.
I suppose if you're drunk enough to stay less than conscious those 40 days would be an easy fast
With 43 kcal/100ml you need about 4.6 liters or 5 qts to satisfy your caloric needs (2000kcal/day). If you even out the intake over the whole day, alcohol levels should be low enough to keep you functioning. Beer also contains a bit of protein and low levels of sodium, potassium and magnesium.
Long term, you'll get scurvy after a few months due to lack of vitamin C and liver cirrhosis from the sustained alcohol use.
I learned once upon a time that a healthy person needs about three weeks to starve to death if they have water. Not sure how accurate it is as it's part of the rule of three mnemonic; 3 minutes without oxygen, 3 days without water, 3 weeks without food. However, it does at least seem reasonably plausible, so we can use that as a baseline.
Now, beer does have some nutrients, but far from enough of the ones you need. It has to be balanced with water to be able to burn the alcohol without dehydrating yourself. I would therefore think that the beer in moderate amounts might help some, but not a lot. Four weeks total, maybe?
It really depends on your starting weight too. A really obese person with only water and beer could go far longer than 3 weeks, probs 6 months or more. They'd start getting in trouble when they exhausted their fat soluble stores of AEDK.
Protein I think would be the issue. There was a case study on a morbidly obese guy that did this with doctors. What I remember is he basically told his doctor he was going to stop eating entirely. They could either help him and give him medical advice along the way, or try to just advise against and he was going to do it anyways. He would take a daily vitamin for general vitamins and I believe some yeast paste to give him protein. I think the dude lost like 400lbs in a year. Had small bowel movements every 30 to 40 days.
Edit: Apparently it wasn't protein but amino acids.
he consumed only vitamins, electrolytes, an unspecified amount of yeast (a source of all essential amino acids)
If you have large stores of fat your body won't catabolise protein until it's basically exhausted. It's pretty good at prioritising carbs, then fat then protein. When it's using protein for energy, you're essentially destroying your muscles and tissue, which is very bad.
Depending on how broadly we define beer here, you could totally end up with one with a surprisingly high protein content. Certainly not enough to live forever on, but I'd bet you could get a lot further than you'd initially think. People can go a long time on just bread, don't see why liquid bread would be much different
I've never heard the yeast paste for protein part of this story before. Every time I've seen it repeated it was just salt and minerals he was supplemented.
I think you would be fine for a long time if you drank old-style beer. Unfiltered, low alcohol content, some remaining sugar/starch and with lots of yeast, maybe some impurities that probably contain amino acids, vitamin b12 and other important stuff.
Beer is 95% water. If you’re counting on it for all your calories, you probably won’t want to drink any additional water or you lose your precious salt and vitamins.
As others have noted vitamin C and salt are probably the most immediate lacking nutrients. If you had a margarita once a week, I think that might be enough.
Numerous people have done a 40-day fast for lent, taking only beer. So that is easily doable. Multiple months is probably possible, but seasons/years maybe not.
High malt, low alcohol beers could keep a person surviving for a pretty long time. You would likely run into some deficiencies in certain vitamins eventually, but that would take months to be a problem.
Generally there is the rule of three's. Three weeks without food. Three days without water. Three minutes without air. Every one is different and circumstances under any of these conditions may very but it's a good rough timeline.
Beer has caloric value but I'm unsure how long that would keep you going.
You'll be in a very rough place after three days of that. I'd be surprised if you could even eat if you wanted to.
I knew a girl who wouldn't eat at all the week she went to a beer festival. It can be done. Don't 😅