Personally, I have some sort of carbohydrate/electrolyte drink during my workout, but that's beside the point.
If you are working out much more than 60-90 minutes, you are either talking too much or taking too much rest. You should always shoot for your workouts to be around an hour long. Gone are the days of Arnold where bodybuilders pumped out 2-3 hour sessions. Well, they aren't completely gone, as some people can somehow manage to effectively do it, but I really believe it is a BAD idea (how do you have a life if you work all day and then lift for 2-3 hours???). Like I said, you will be developing high levels of cortisol after that point and to be blunt, you're wasting your time.
I also attribute the 2-3 hour workout to the newbie syndrome... It happens every year. Come New Year's, people make their resoultion to get in shape, and they flock to the gyms in droves. They then proceed to kill themselves with 2-3 hour workouts because they don't know much better, and before you know it, they're burned out, and they give up, usually within 2-3 weeks.
*sigh* I'll guess get off my soap box now

Just keep your workouts short and intense and you won't have to worry about it.