While watching a football game and eating popcorn and Gatorade with a friend, we both had a major Need To Know: how long could we continue doing this (necessary football, airtime, tv and electrical life, etc., taken as a given)?
Long enough to be unhealthy.
Gatorade is basically sugar water with a pinch of salt and very little else. It has only a bare trace of vitamin C. Any equation given for bread and water is going to be approximately the same for corn and water.
See
A Straight Dope Classic from Cecil’s Storehouse of Human Knowledge
Can man live by bread alone?
IIRC corn (i.e., American corn, maize, from which popcorn is made) contains no tryptophan. Tryptophan is an essential amino acid. Without it you will get a wasting disease. (I think there is tryptophan in wheat, so bread is much better.)
On that diet you would probably be missing a lot of vitamins too. There are probably trace amounts of some vitamins in corn, but not enough to keep you alive. Maybe scurvy would get you first, unless they put vitamin C in Gatorade, or some other vitamin deficiency disease.
In my 20’s I went for about 3-4 years pretty well living on popcorn and hotdogs at arenas while I went from ice-rink to ice-rink playing hockey all the time. I was in the best shape of my life. I don’t think I ever got sick once. Never took vitamins and just drank soft drinks. I’ve always thought hat the 4 main food groups is just a scam to get us to buy all the food groups which benefits the suppliers. I’m no Doctor but I am very healthy and eat much better now but think our bodies can live on almost anything. But I still love my popcorn, not so much the hotdogs anymore.
That’s interesting. I was all set to do some conversions after reading Cecil regarding how the breakdown of the starch of popcorn compares to that of wheat. In my WAG, it would affect energy expenditure of the metabolism, which would affect the amount of time left before you die.
Of course, if you add real butter (although artificial butter tastes better), all bets are off re amino acids, right? 
I’ve had a long-time-brewing question in this vein – something like "How long could you live on BREAD, WATER, and a CENTRUM?
…but now I don’t want to look like I’m biting off another OP.
I was thinking the same thing re the addition of a multivitamin. So don’t feel bad at all.
Plus, that wasn’t a hijack (or a pun that worries me :)) IMO. Just a gentle extension of the discussion, in proper SDMB style.
No way. Amino acids come from protein. There is no significant protein in butter. It’s fat. There is some protein in corn, but it has no tryptophan.