Hi, my name is JakeS, 38 w/cf. The reason you NEED electrolyte replacement, especially after exercise has everything to do with CF. Gatorade has high amounts of sodium. We lose so much more sodium(and potassium, magnesium, calcium(the other electrolytes)) through sweat, breathing, phlemn, and stools than most people due to cf. Electrolytes act on a cellular level to transport fluids in and out of the cell. We need sodium to transport water on a cellular level, thus why cfers are chronically dehydrated. So yes you crave gatorade because you need it. Electrolytes, magnesium and potassium are critical for proper absorption of nutrients. This is one reason so many of us(me included) suffer from chronic malabsorption. Much of our food goes undigested w/out proper replacement of mag. And pot. These are found in gatorade in low levels, but you need more. Also low levels of pot. And mag. Lead to low levels of calcium(the other electrolyte) This is why most cf patients have low bone density. I recommend that you do several things. Before i say what they are, a caveat. I have had a love hate relationship with gatorade my whole life. Love it, for the quick electrolyte replacement, hate it for the sugar & low ph. As a result of growing up on gatorade my teeth have rotted out, and i now have to wear partial dentures.
A couple of years ago, i finally figured out some electrolyte replacement therapies that do not rot my teeth(nuetral ph) This also happens to be good sources of potassium and magnesium, calcium, and sodium. Coconut water is natures electrolyte replacement. Neutral ph, no sugar. High in mag. And pot. Not so high in sodium. So this is what i do. I combine coconut water with fruit juice(taste), then add salt. You can add as much salt as you like. The good thing about needing sodium is that you crave it, and can palate more than most people.
Now, with coco water/fruit juice/salt combo I not only get electrolyte replacement, but also chronic malabsorption is improved, and my teeth don't suffer. Also that calcium supplement your doctor has you on, will be absorbed properly, therefore better bone density. Also i have found, liquid cal/mag/zinc supplements absorb much better than the pill supplements.
I am not advocating that you not enjoy your gatorade, especially after a run. It is just good to know that there are better, more complete electrolyte replacement options out there. I am advocating complimentery therapies, meaning there is more than one way to slay the electrolyte beast. Stay strong.