The digestion takes two hours to be complete if the meal is light, easy and no full of fat, 4 hours if the quantity of carbs is high and the meal too elaborate. Since many races start before 9 a.m. or earlier, you'll have to set your alarm for a very early wake-up to hit that four-hour window.
If that's not realistic, you may choose to eat your entire prerace meal just two hours before the start, choosing a light but complete breakfast.
You can eat an energy bar 60 minutes and drink a sports hydration drink up to 20 minutes before the race for an extra boost if you can't eat just before the race.
Dott.ssa Annalisa Faè R&D ProAction