I noticed something this weekend while I was outside, camping, with a day-time heat index of 115 degrees: I was actually a little constipated. This problem went away as soon as I returned home to the A/C. Apparently you can sweat enough water out of your system that it won't end up in your intestines.
Mind you, 115 degrees is pretty miserable, but if you're dreading July 4th parties because of D, don't worry, just stay outside all day!