Runners planning to run a race should pay attention to their nutrition during the last week before planning to run a 5k , 10K , half marathon or a full marathon.
Nutrition last week before the big race
Increase your daily intake of carbohydrate, particularly whole grains, fruits and vegetables, during training. An increase in daily protein intake is also recommended, with the balance coming from dietary fat.
Carbohydrate is the major fuel used during training, and both carbohydrate and protein may help facilitate muscle recovery.
Practice fluid and carbohydrate intake, both as water and sports drinks, during training so that you are comfortable with the procedure during the marathon. Know the sport drink that will be used in your marathon, and train with it. You may also wish to experiment with carbohydrate gels (some contain caffeine; see comment below on Running a faster marathon); if the marathon provides gels at points on the course, try to experiment with the specific brand.
P.S. Remember to take plenty of sleep during the week so that, even if you don’t sleep on the eve of the race, it won’t matter.