My friend’s been talking about fasting, and he claims that someone like himself (6’1", 240lbs) can go a year without any food as long as he has plenty of water (with minerals). I say no way in hell, and he’d be dead in 40 days-- or 2 months at the absolute max. Who’s right?
Welcome to the SDMB. Now proceed to your handy-dandy dictionary and look up “hyponatremia”. If your friend lies perfectly still, I give him a week or two. If he’s going to be participating in any kind of strenuous physical activity, expect him to go into shock in a few days, and pass away shortly thereafter.
Have a nice day 
Not to be arguing with a medical definition but I thought people who went on hunger-strikes would live for 50 days.
Actally…here is a cite that lists ten different people who made it for 46-73 days ( http://larkspirit.com/hungerstrikes/ ). Of course, they may have had some nourishment other than water that I am unaware of but I think you can go far longer than two weeks with no food.
Okay, a week or 6. But definitely not a year.
I got that from http://www.emedicine.com/emerg/topic275.htm
Maybe it takes a few weeks for serum sodium levels to fall to the two-minute-warning level. But the last part of my post is accurate I believe. This past AIDS Ride, we had a case of hyponatremia because a rider didn’t like the taste of gatorade, and drank only water.
Before anyone busts me on this I do not mean that the hunger-strikers ate anything but rather had some kind of dietary supplement added to their water (or they took a pill). I’ve done a quick Google but I can’t find information on how long things like scurvy, beriberi or rickets take to manifest themselves (they are all due to vitamin deficiencies). I know some we have a lengthy store of some vitamins but others may disappear more quickly. Vitamins aside what about salt? All the water in the world won’t help you if you don’t have some salt in your system to hold on to that water. I know exercise in hot weather can dump enough salt from a person’s body very quickly, as Attrayant pointed out, sufficient to kill a person.
Also, I would assume that towards the end of these peoples’ lives they would either be too weak to drink water if not outright unconscious. Perhaps (again I don’t know) they were hooked to IVs that prolonged their life.
In short, I do not know if a person can live 50+ days on water only. Without minor quantities of vitamins and salt (and maybe a few other things) I suppose someone might expire much sooner.
Anyone know the straight dope on vitamin and salt deficiencies?
From Attrayant’s link:
Perhaps the reason fasting people can go so long is 1) because it’s a more gradual decrease in sodium levels, and 2) they may not be consuming what the article refers to as “free water” (seems to be synonymous with tap water).
On a personal level, when I was 16 I stopped eating for six weeks. Nothing but water… and I was still relatively active (worked full time, biked to and from work which was about 2 miles each way, but as the cause of the not-eating was significant depression, I spent the rest of the time in bed). Lost 45 pounds after the first month, wound up with a pretty severe case of mono, lost another 10 pounds over the next 10 days. By the time I began recovering I was hovering around 100 pounds (on a medium-to-large-framed 5’6"). I don’t recommend it, and highly doubt that the OPer’s friend would make it a year.
-BK
This site has the record at 76 days
http://travel.yahoo.com/p/travelguide/760656
These were confined prisoners in Corc, not marathon runners on a diet.
This site shows benefits from fasting:
http://cinque.getwebspace.com/facts.html
I myself can barely last 10 hours due to my metabolism before sever headaches and stomachaches prevail.
According to that scurvy will set in after about six weeks. Vitamin A, D and B deficiencies take much longer (for instance Cecil says we have a two year supply of vitamin A stored).
So, it would seem our hunger-strikers would see scurvy symptoms popping-up after 42 days without a dietary supplement.
Wait a second - didn’t the OP mention minerals?
I would assume this means vitamins and salts which would rule out scurvy, hyponatrimia, hypokalimia, etc.
So - assuming you were drinking and taking a multivitamin sufficient to meet the basic daily requirments - how long?