WDW is not the Olympics. You get plenty of what you need in the foods you eat ie: sugar, salt, carbs...
If you feel it necessary, 1 bottle of sports drink in the middle of the day, supplemented with drinking water is all you need. Too much salt is actually bad for you, so the more salt you ingest, the more you have to drink. Remember salt will increase your blood pressure.
Actually, the best thing to do when at WDW in the heat is to eat a light but good breakfast: which contain a balance of carbs, protein, and fruit such as a melon plate with yogurt and granola or a muffin,. Eating a heavy fat and sugar/salt rich breakfast is not a good idea, either is a lot of coffee which is a diuretic (sp?). Have a glass of OJ and water instead. Drink water throughout the day, and keep lunch on nthe lighter side as well, and try to keep alcohol during the day to a minimum. Keep dinner your treat meal. For every drink or cup of coffee you have, you have to add 8oz of water. Salty foods like popcorn, hotdogs, turkey legs etc...are terrible in the heat. You will swell up like a tick. Retaining water is not the idea, keeping hydrated is -there is a difference.
What you EAT is just as important as what you drink. You don't want to go to the parks in 100 degree heat and 100 humidity with an order of Tonga Toast and a pot of cofee in your stomach. Just think of what your body has to go thru to process all that sugar, carbs and fat, which raises your insulin levels immediately making your body work that much harder....You will retain water, feel sluggish and feel hotter. Your body is working hard to keep cool AND process all the food from a heavy meal.
Eating and snacking on the right foods and keeping hydrated is sufficient. Taking breaks to the pool and getting into AC now and then to cool your body down is also improtant.
So when it's hot, eat light, eat often (every 3 hours: fruit, grains and protein) limit sugar and salts, drink water, and keep cool.
Dinner is a better time to splurge - but still maintain your water intake. It will make you fel better the next day
