11 misconceptions about training for a marathon that you should stop believing

Because you're increasing your exercise to train for a marathon, it might seem like a good idea to cut some calories at the same time to lose weight.

"This isn't the time to multitask" Leslie Bonci, owner of Active Eating Advice, a sports dietician for the KC Chiefs, and a marathoner herself told Business Insider.

Because you're running such long distances, the body needs to stay fueled to prevent you from feeling fatigued. Plan major shifts in your diet for while you're not training.

If you go overboard on the carbo-load the day before the race or during your training, you could risk being too full on runs, as well as take in energy your body doesn't necessarily need, Bonci said.

If you're only going out for a 30-minute jog, 16 ounces of a sports drink might not make the most sense.

According to Bonci, electrolyte and carb-heavy sports drinks can come in handy for runs longer than one hour. After that threshold, runners might need anywhere from 30 to 60 grams of carbohydrates per hour to replenish what long-distance running is using up in the body. At that point, sports drinks can come in handy.

At the same time, runners should be sure to fuel up before training runs and on the day of the race. Running a race on empty could lead runners to getting tired too early in the race.

If you picked the night before the race to try deep dish pizza for the first time, it might be time to reconsider.

On the day of a race, it's key to make sure your gut isn't preoccupied with digesting something it's not familiar with, Bonci said. You're going to need every part of the body in race mode.

On race day, runners will be producing endorphins and adrenaline that'll keep your energy up in a way that they wouldn't while you're sitting at a desk early in the morning. The needs for caffeine differ then, too, Bonci said.

Caffeine on race day can have the undesired effect of making runners' hearts race, which can be distracting while on the course, she said.

While a snack, gummy, or tube of gel might seem like a quick way to get those carbs the body's using up, it's important that runners don't forget to hydrate as well.

Drinking water alongside the energy-boosting foods ensures that runners are staying hydrated and can help the body digest and start to use the energy from the snack faster than if the snack was eaten alone, Bonci said.

That said, there are ways to overdo it. Bonci calls it the "Barista Effect," of mixing together sports drinks and gummies and other snacks, much like asking for a drink with extra flavor shots and extra foam on the top.

The concentration of that many carbs and liquids during a race can have a detrimental effect. "It's too many things," Bonci said.

While it may be tempting to reach for the nearest snack after a long run, it's important to be strategic with your refuel.

Protein is key to rebuilding muscles and will go a much longer way than a bowl of pasta alone — or even a plate of leafy greens, which might be filling but won't have all the replenishing nutrients a runner might need. Runners are using up a lot of energy during the run, it's important to sustainably get that back.

After a marathon, Bonci said she likes to recover with a meal at a Middle Eastern restaurant.

While it might be so tempting to reach for a beer at the end of a race, it's important to get something else in your system first to replenish the liquids, electrolytes, and carbohydrates lost in the long run.

There's evidence to suggest that going right to the alcohol can delay muscle recovery. So drink the orange juice first, then the vodka, Bonci said.

"People will thank me when able to walk down the stairs the next day," Bonci said.