Besides dystonia, I also have hypertriglyceridemia, elevated levels of triglycerides in my blood, which increases the rates of pancreatitis, stroke, and cardiac dysfunction; consequently, I am on a very restrictive diet...low carb, VERY low sugar, low fat. Other than the occasional piece of baked fish or seafood, I am also a vegetarian. This means that I must derive much of my energy from protein. The problem I have, especially for eating/drinking while riding, is that so many of the protein snacks and hydration drinks are loaded in sugars and other carbs. So, now I will share my regimen for snacks & drinks while riding....
For Hydration
It is imperative to replace lost electrolytes on those long bike rides. Believe me, I sweat worse than a virgin at a prison rodeo! Even the reduced calorie Gatorade drinks contain a considerable amount of sugar...at least by my standards. I used to only take water, and I would slip in the occasional low-cal drink mix packet that stated it was for energy, which meant that it contained additional B vitamins and caffeine. This does not help replace much-needed sodium and potassium lost in sweat.
Then, I found Powerade Zero. I pick it up as an 18-pack at Sam's Club. It is DEFINITELY worth the cost.