To expand a little on what keterys just said...
In the DMG, in the section on environmental dangers (starvation, thirst, suffocation) -in that instance- it says explicitly that if you fail your skill check against said environmental dangers (starvation, thirst, suffocation), then you lose a healing surge and if you do not have a healing surge to lose then you lose 1hp/level.
As to why it's 1hp/level, it is true that it doesn't make much sense taken in itself. But if you start thinking of ways that a PC can raise their surge value (through magic items and feats, or a dragonborn with the racial bonus to surge value) you suddenly have an awkward situation where someone who is all customized to be hardy is suddenly the one most winded by starvation compared to the more frail PC who has no such customization and is also starving. The advantage being that it is the hardy PC who is typically less likely to fail the checks to be starving in the first place.
Taking that a step further, it is possible to extend the 1hp/level if no surges remaining to other types of level loss (such as a wights). But doing so is not explicitly spelled out as being applicable to ALL situations where you have no surges remaining. Some might read it as saying that the 1hp/level is just a special situation for environmental dangers while others might think it applicable to any situation where surges could be lost but not available -- so do whatever works for your group's interpretation/preferences.
Personally, I think if a creature is trying to drain the very life out of you and you don't have any surges left, it should still be able to drain something out of you. So the 1hp/level sets a good prescedant. But that's just my opinion and what works for me. You/your group's preferences may vary.
I don't miss level drain. It was never a good mechanic.
Agreed - it was always a sloppy situation where someone would have to try and redo stats on the fly all the while being upset and shocked by whatever just happened to cause it in the first place.
I will say that the raise dead penalty from the 4e ritual is considerably "cleaner" (perfect, no, but cleaner, yes).