How to Prep and Fuel for a Marathon

The Do's and Don'ts for the Final Days Before the Big Event

Updated: March 26, 2025 by Joe Rubio

Close up shot of GU energy gel, Honey Stinger Waffle and Cliff Energy Chews

You've put in months of hard work to get ready for your marathon, a little pre-race prep and planning will help make your marathon a much better experience. The fuel you eat, the shoes you wear, and the gear you use should all be tested well before race day to avoid any unwanted surprises. By dialing in your strategy ahead of time, you’ll set yourself up for a smoother, more confident race.

Helpful Training Tips Leading into Your Marathon

Training for your marathon is the perfect opportunity to test which nutrition and gear work best for you. Avoid making any major changes to your diet, clothing, or shoes right before race day.

DO practice using the shoes, socks, shorts, and bras one or two times before during your long runs or lead-up races so you are confident they’ll work for you on race day.
DO practice using the hydration and gels you plan on using on race day a few times in the leadup long runs. Do your best to figure out what hydration and gel combination works and how often to take them.
DO pack your race day outfit, shoes, gels, and essentials in your carry-on luggage if you are traveling by plane. The last thing you want is for them to get lost in your checked bag and have to run in all new gear.

What to Eat the Night Before

You may have learned from training that what you eat the night before long runs will affect your performance the next morning. The same goes for race day. This is especially true if you have a sensitive stomach, but it can apply to any runner.

DO eat what you normally would the evening before a long run. Eat what you know.
DO opt for an easily digestible, familiar meal.
DO hydrate well.
Avoid greasy, heavy, unfamiliar foods.
Avoid alcohol and caffeine.
Avoid overeating. Comfortably full is plenty.

Prepare for the Morning

The morning of the race is typically very early and can be stressful, especially if you have to factor in shuttle times, eating a proper breakfast, and getting to the starting line on time. That's why it's a good idea to prep everything you need the night before. Setting out your gear beforehand helps to avoid a half-asleep panic attack in the morning because you can't locate your bib or running shoes. Remove unnecessary stress by preparing everything you can prior to hitting the hay.

DO lay out everything you need for the morning the night before, including your bib, clothes, shoes, breakfast, water, anti-chafe salve, etc.
DO make a checklist that you can use to make your routine as easy and brainless as possible.
DO NOT expect to get in your normal warmup or have ready access to outhouses. As much as possible, take care of both before leaving the hotel to hop on the shuttle bus.

The Day of the Race

Try to be as well-rested as possible in order to feel physically and mentally prepared to complete your marathon. Expecting to get in a full restful night of sleep the evening before the marathon is probably not very realistic.

DO ensure you get plenty of rest in the week leading up to the race, and get extra sleep two nights before the big event. You probably won’t sleep very well the night before the marathon.
DO your best to get some sleep the evening before the race. It’s much more important to get in normal sleep the last few days before traveling to the race.
DO go to bed the night before when you feel you can get some sleep. Going to bed before you’re tired will only result in you tossing and turning. Worrying about not sleeping will generally drain you.
DO wake in plenty of time to gather your thoughts and gear, grab a bite to eat, use the restroom, and have a focused, purposeful morning.

Stick to What Works

As you prepare for race day, remember that training is the time to fine-tune your nutrition, gear, and race-day strategies. Sticking to what you’ve tested and know works best will help you feel confident and strong when it matters most. Avoid last-minute changes to your diet, shoes, or clothing to minimize risks and ensure you’re ready to perform your best. Trust your training, stay consistent, and enjoy the journey to the finish line!

Joe Rubio

Joe Rubio is the owner of Running Warehouse. He has been on the running scene since 1977. He has had various roles including as athlete, coach, race director, author, and shoe expert. Joe has an MS in Physical Education from California Polytechnic State University in San Luis Obispo. He is a USATF Level II certified coach. He has coached athletes at the highest levels (National Championships, Olympic Trials, and World Championships).