Eating and drinking remains one of the ultimate keys to success in running ultras. It is one of the most important factors in determining the outcome of a performance. Novices and veterans alike are vulnerable to missing an ingredient that can make or break their day. Runners should look at each of these areas in planning for an ultra. The four groups overlap and are normally used in combinations, but missing any single one can make for a miserable ultra.
Runners can lose up to a liter of fluids per hour depending on weather conditions.
Many studies have been done on sweat loss during exercise and replenishment of fluids. This is done in order to monitor weight loss. Results in mandatory withdrawal from the run. The key to maintaining weight is to take fluids early in the race. The answer varies depending on weather conditions, running speed, and body mass.