Taper Week Nutrition and Carb Loading for Running

Updated: Sep 25

By Holley Samuel MEd, RD, LD, CPT

Photo by: iRunFar Kristen Kortebein Race season is among us, and for many runners, this could mean gearing up for a goal half or full marathon. Hopefully, you have been practicing your fueling strategy throughout the training cycle in preparation for race day. If not, we will discuss some key strategies to implement during these peak training weeks to prepare you to race.

What is the objective during taper leading up to a goal race?

Taper periods before a half or full marathon are traditionally two to three weeks in length. The volume of training decreases, and recovery is prioritized. For many runners, the taper can feel like a welcome break where training load is reduced intentionally to allow for adequate recovery in preparation for race day. For others, the taper may be a strange time where they feel like they aren't doing enough. They may long for those higher mileage weeks or feel the need to "test" their performance on training runs to prove that they can still run specific paces or intensities. Attempting unplanned effort sessions this close to a race is not recommended, as the taper signifies that "the hay is in the barn." While no more fitness can be gained in the weeks leading up to a race, it can be easy to self-sabotage progress due to restlessness and not feeling confident in training.

Should I eat less because I am running less?

No. Runners should attempt to maintain their recommended caloric intake needs to achieve a stable energy balance, as they usually would when optimized during peak training weeks. During the two to three days before an event that will take at least 2-2.5 hours or more (like a full marathon), a runner should focus on increasing the number of calories that come from carbohydrates.

Runners may also experience weight fluctuations in the taper, making them feel the desire to cut calories, carbs, weigh themselves obsessively, or increase their mileage. Responding in this manner can be detrimental to performance because the taper is all about recovery. Being in a calorie or carb deficit state, adding unnecessary training volume, or becoming hyper-focused on weight as a marker of fitness does not promote optimal recovery. Instead, runners should implement recovery strategies like adequate sleep, nutrition, stress management, and training deloading to optimize the effects of the taper. Although this can be mentally challenging, it is the key to experiencing peak performance on race day.

To carbo-load or not to carbo-load?

During training, about 45-65% of calories typically come from carbohydrates, but during the 2-3 days before a marathon or long race effort, 65-75% of calories should come from carbohydrates to efficiently top off glycogen stores.

Glycogen is stored carbohydrates, and most humans, on average, can store about 2000 calories of glycogen in their liver and muscles. Endurance efforts lasting longer than 2 hours tend to deplete glycogen storage, which is why it is vital to fuel on long runs and long race efforts. It's essential if the ultimate goal is to run a fast half or full marathon time, as the body will burn through glycogen and carbohydrates more quickly at higher intensities. Runners should also note that every 1g glycogen is stored with 3g water. Water retention is common up to 3-5lb when carbo-loading; however, this is not necessarily bad when considering performance. If weighing oneself creates a barrier to adequate fueling measures, runners should consider avoiding the scale in the days leading up to a race.

Whether male or female in any phase of the menstrual cycle, runners should focus on eating between 10-12g/kg body weight in carbs the 2-3 days before an endurance event lasting longer than 2-2.5 hours in duration. To put this into context:

150 lb person /2.2= 68kg

68kg x 10-12= 680-818g carbohydrate per day in the 2-3 days leading up to the goal race

680g carbohydrate is about 11 bagels worth of carbohydrate

For many recreational runners, who tend to undereat carbohydrates at baseline, this may seem like a lot to take in each day. And these general recommendations may not apply to certain medical conditions or circumstances; however, for most runners, carbo-loading properly will ensure they optimize their chances at a PR in their race.

It's essential to practice fueling strategies before race day.

To eat this many carbohydrates and reduce the risk for gut distress during their race, runners should also consider reducing their fiber intake and ensuring they are optimally hydrated in the days leading up to their event. An athlete may need to consume white breads and refined grains over whole grains, drink liquid carbohydrate sources, reduce veggie intake, and eat frequently throughout the day. Practicing these fueling strategies during the entire training cycle and training the gut to tolerate sports nutrition recommendations on the run is key to ensuring a good experience and performance on race day.

What about caffeine and alcohol?

Other considerations for taper nutrition are reducing alcohol and monitoring caffeine intake. While in moderation, alcohol may not decrease performance, in excess, it may lead to dehydration, gut distress, and sleep disturbances. Some runners feel avoiding alcohol entirely in the weeks before their race benefits them, while others find having a drink or two in moderation has no impact on their performance. Caffeine can be used as an ergogenic aid in boosting performance; however, for some runners, it can suppress the appetite, trigger anxiety or gut distress, and in doses greater than 400mg, may also cause dehydration.

Suppose a runner tolerates caffeine well and knows using it during or around their race aids in their performance without any previously discussed side effects. In that case, they may not need to worry about altering their caffeine intake. Some may even find that decreasing their caffeine intake in the days leading up to the race and then having their regular dose on race day may increase their sensitivity to caffeine and improve performance. Practicing this technique in training is vital, so no unwanted side effects come as a surprise on race day. Runners who are sensitive to caffeine and unwanted side effects should avoid caffeine around their race.


As a dietitian who works with runners on their fueling strategies, I recommend writing out your plan for the days leading up to your race and on race day itself. Take note of how many carbohydrates you need to consume and come up with a plan on how you will make that happen. Identify where the food will come from and if you are traveling, create a plan in case things become logistically challenging so you can troubleshoot from there. Practice this in training around your long runs, and don't be afraid to make adjustments if necessary. If you are unsure how to implement this specifically to your situation, work with a sports performance dietitian to develop a plan unique to you.


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  2. Lara, B., Ruiz-Moreno, C., Salinero, J.J. and Del Coso, J., 2019. Time Course of Tolerance to the Performance Benefits of Caffeine. PloS one, 14(1), p.e0210275.

  3. Vitale K, Getzin A. Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations. Nutrients. 2019;11(6):1289. Published 2019 Jun 7. doi:10.3390/nu11061289

  4. Wohlgemuth, K.J., Arieta, L.R., Brewer, G.J. et al. Sex differences and considerations for female specific nutritional strategies: a narrative review. J Int Soc Sports Nutr 18, 27 (2021). https://doi.org/10.1186/s12970-021-00422-8

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