What To Eat Before a 5K Race, According to a Registered Dietitian and Runner

Here to give her expert tips on what to eat before a 5K, what to avoid, and how else to best prepare yourself is registered dietitian and Cook, Eat, Run author Charlie Watson, RD. Watson helps runners (of all levels) properly fuel their bodies during training as well as on race day. Keep reading for her insight.

What food should I eat before a 5K run? The night before? The morning of?

While determining what to eat before a race is an individual process, there are a few golden rules to fueling up properly.

1. Stick with foods you know your body digests well

Before getting into the specifics of what to eat, Watson wants to make something clear: race day is not the time to experiment or drastically switch up your eating habits. "Make sure you practice to establish what works for you," Watson says. "When it comes to pre-race fueling, what works for one person might not work for another." Think back to your training: What did you eat before some of your best, long runs? If a food consistently made you feel good during your training, chances are it will on race day, too.

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2. Eat your pre-race meal at least an hour before it starts

According to Watson, when you eat matters, too. "Ideally, eat about an hour before [the race] starts, although some people [feel best] eating two to three hours before a run," she says. Most importantly, she says not to eat pre-run fuel immediately before your race. "When we run, blood flow to the digestive system reduces by up to 80 percent, meaning if you eat too late, much of what you eat will go undigested while you run and can feel uncomfortable sitting in the stomach," she says. It also means the nutrients in your pre-race meal won't be used as energy until much later because of the delayed digestion.

3. What should I eat for breakfast before a 5K run? Make sure your pre-race meal has carbs.

When it comes to the important nutrients to include in your pre-5K meal, Watson says carbohydrates are the biggie. "You want to mix slow- and fast-release carbs to get that pre-race energy boost that will sustain you throughout the three-plus miles," she says. The best food for runners, slow-release carbs include foods with a lower glycemic index that are less processed and higher in fiber (so, oats, whole grains, sweet potatoes, that kind of thing), while fast-release carbs tend to have a higher glycemic index, like fruits and juice, to give you immediate energy.

4. Keep it simple

While it's important to keep the nutrient balance of your pre-race meal in mind, the actual prep work shouldn't be complicated. After all, the majority of races are in the morning, so you won't have a lot of time to make an elaborate breakfast. Some of Watson's favorite pre-race breakfast foods to eat before a 5K include:

• Whole grain toast with jam
• Oatmeal topped with fruit
• Banana with nut butter

5. Get your carbs at dinner, too

The night before a race is also a good time to give your body some carbohydrates that can be used as energy the next day. Sweet potatoes, brown rice, and chickpeas are all examples of healthy carbs that can be used to fuel your run. A couple meal ideas from Watson's cookbook include sweet potato gnocchi, salmon and sweet potato fishcakes, and Balinese beetroot curry.

Watch the video below for more tips on what to eat for optimal energy:

What foods to avoid before running? And other tips to keep in mind

It's important to know what you shouldn't eat or do before a 5K race in order to keep up the pace.

1. Avoid high-fat foods before a race

As far as what not to eat before a race, fats are going to be least beneficial. “Fats remain in the stomach longer than any other macronutrient because of their complicated digestive process,” clinical nutritionist Nicole Lund, RDN, of the NYU Langone Sports Performance Center, previously told Well+Good. That means you'll want to veer away from foods like burgers or anything fried the night before. Lund also recommended avoiding foods with sorbitol (a fruit-derived artificial sweetener), which could irritate the digestive system.

2. Don't forget to hydrate

When prepping for a 5K, it isn't just about what's on your plate; hydration matters, too. "It's important not to start your race dehydrated as it's very hard to 'catch up,'" Watson says. "Ideally, you want to meet your fluid requirements—usually between two to three liters—each day in the week leading up to the race so that you don't find yourself gasping for water at the first aid station." Watson adds that if you tend to sweat a lot, you may want to consider using electrolyte tablets the day before, morning of, and afternoon after a race, too.

3. Keep your coffee habits the same

If you're wondering whether your morning cup of joe will help or hurt your run, Watson reiterates her advice to do whatever has worked for you in the past while you've been training. "If coffee is part of your morning ritual, if you like the caffeine boost, or if coffee helps get things moving before the race, then stick with it. But don’t start having it pre-race if it’s not something you’ve done before…trust me on that."

4. Plan your post-5K meal, too.

Besides figuring out what to eat before a 5K, Watson says to consider what you'll eat when you're done, too. (A nice mental picture to make those miles fly by faster...) "After a race, you want a mix of carbs and protein, ideally in a 3:1 ratio," she says. "It doesn’t have to be complicated. I tend to have a skim milk iced latte after a 5K. Otherwise, a mix of eggs with toast or a smoothie can work, too."

5. Is it ok to run a 5K on an empty stomach?

Like most aspects of training and running, what (and whether) to eat before a 5K is a personal choice. However, to get the most out of your run, and perform your best, experts recommend fueling up. If your body doesn't have carbohydrates and protein on hand, it will break down your fat and muscles for fuel instead. Getting this less readily available energy adds an additional strain on your body, which could negatively impact your workout.

“Trying to force the body to use fat as fuel can negatively affect your performance,” Natalie Rizzo, MS, RD, sports dietitian and founder of Greenletes, previously told Well+Good. “This means you won’t be able to work out as hard and may even feel like you’re losing your fitness level.”

6. Should you eat during the race?

This is another personal choice.  A 5K typically won't take the amount of time experts say requires a mid-run snack, which is 75 minutes. But if you're curious about juicing your body with fuel during a race, check out this guide to what to eat during a marathon.

With these tips in place, you're bound to go into your 5K energized and ready to kill it. Now that your mind is cleared up about what to eat, you can focus on other pressing matters: like what exactly should be on your race day playlist.