top of page

Eating right for the big race

Nutrition is the silent yet powerful partner for sports and optimal athletic performance. As we approach the final weeks of training for the Boston Marathon, many of us are getting our last few long runs in, replacing our sneakers, perfecting our race day attire, and last but certainly not least, ensuring our racing nutrition plan is air tight (if you do not have one yet, it is time to start)!

Endurance sports such as marathons place a great deal of stress on the body. Ensuring that we are fueling and hydrating properly can make the difference between a PR and a DNF. Endurance sports increase the body’s need for both macro and micronutrients. Training in a caloric deficit can lead to extreme fatigue, irritability, injuries, and frequent sickness. As a rule of thumb, a runner uses ~100 kcals for every mile that they run. Therefore, if they have a 19 mile run, they are likely burning close to 1900 kcals! It is also important to not over consume foods or use running as an excuse to eating anything that you would like, as this can actually lead to weight gain. Aim to consume 3 meals and 2-3 snacks daily using the below percentages as a guide:

  1. 55-65 percent of calories from carbohydrates (grains, pasta, bread, etc.)

  2. 20-30 percent of calories from fat sources (oils, avocados, nuts, etc.)

  3. 10-15 percent of calories from protein (fish, meat, chicken, beans, etc.)

The Day Before

A common mistake I see in a lot of runners is overeating the night before a race. There are often sponsored pasta dinners the night before a marathon, but you want to feel comfortably full and not “stuffed” before going to bed. I like to say too much carb-loading can lead to a massive “carb-unloading” (aka GI issues) during the race. I like to think of the day prior to race day as an upside down pyramid with breakfast being my largest meal of the day, followed by a moderate lunch and dinner. I avoid most whole wheat products the day before and increase my intake of white breads and simple sugars to increase my glycogen muscle stores. I also suggest using simple carbohydrates such as jello, juice, and jams 1-2 days prior to the race to increase glycogen stores without overloading the GI system.

Race Day

It is important to eat breakfast approximately 3-4 hours out from the start of the race. I recommend keeping it low in fat and fiber, mainly simple carbohydrates, and incorporating some protein (eg. Two slices toast topped with peanut butter and honey). During the race, aim to drink ~3-6 oz. at each water stop (~1 per mile). You can alternate between water and Gatorade at the hydration stations. Gatorade contains electrolytes to help replenish the sodium lost in sweat preventing hyponatremia. You should also aim to take in approximately 30-60 g of Carbohydrates per hour. I usually use the 45 min mark on my watch to ingest an energy gel (you can also use real foods or other premade sport products). If taking a gel be sure to wash it down with water to avoid GI distress from delayed gastric emptying. If you start to feel a “sloshing” in your gut, back down on the fluid intake to avoid hyponatremia.


Within 30-45 minutes post-race it is recommended to consume a snack composed of carbohydrates and protein (ideally in a 4:1 ratio). A higher glycemic index carbohydrate is beneficial here since it elicits a greater insulin response, leading to rapidly restored glycogen stores in the body. Also be sure to consume adequate fluids to help encourage urination and to help urine return back to a pale yellow color. Frequent meals/snacks can ensure that you recover properly.

Take-away Points

The most important point that I can stress is to practice, practice, practice your nutrition! Nutrition is highly individual and there is no “one size fits all” approach to fueling. The nights before your long run, try out dinners to find out what helps you feel best. During your long runs, practice taking in different types of carbohydrates to ensure you do not experience GI distress. I do not recommend any new foods or drinks on the week of or day of an endurance race, since this can lead to unpleasant outcomes on the race course. Since you have enough to think about on race day, your race day nutrition plan should be something that is already figured out, leaving little room for error.

If you have any questions or are experiencing any issues with your fueling strategy/energy levels, I recommend scheduling a nutrition consultation sooner rather than later! You can schedule an appointment by calling 617-355-3501.

Happy racing!

11 views0 comments

Recent Posts

See All

National Biomechanics Day

National Biomechanics Day is celebrated annually on April 10. We celebrate Amy Whited, our biomechanist, every day since we are so lucky to have her on staff. Even though we know what she does is impr


bottom of page