Avoid the following:
Salt – Salt consumed during the 24 hours before the race will produce blood more concentrated in sodium. Fluid is then taken from muscle tissue and other areas, reducing your capacity for performance through dehydration.
Fat – The more fat in your diet the day before a long one (especially after 2:00 p.m.), the more sluggish your digestive system and the less effective the food will be in delivering nutrients that can be used during the race. Because it takes a longer time to process, a fatty meal often causes stomach or bowel problems the next day. Fat is not a good thing … in the long one.
Fiber – Too much loading up on fiber foods the days before the long one (or race morning) can lead to unloading. Not only is this embarrassing, it’s dehydrating.
Large meals the night before the long training sessions or races will still be in your intestines, drawing blood away from the exercising muscles the next morning.
Alcohol – This central nervous system depressant will leave you with less motivation the next morning. This will interfere with your goal, whether it be for a time or to finish. Alcohol is also a major dehydrating agent.
Learn more about The Endurance Diet in Jeff’s book Nutrition for Runners.