I'm running my first marathon. A sports dietitian helped me put together the perfect meal plan.

• Carbo-loading involves eating more carbohydrates to fuel up before a marathon.
• Consuming simple carbs, lean protein, and water helps you store energy before the race.
• It's also important to reduce fiber and fat intake, as well as avoid spicy or rich food.

The week before a marathon, runners are supposed to run fewer miles while carbo-loading — eating a lot of carbohydrates to store up energy for the big day.

This is something I've been looking forward to as I prepare to run my first marathon on November 3. Oh, I have to lie on the couch balancing a full pizza box on my stomach? I'm doing the work by tenderly undressing a burrito in bed?

Now that the week is here, I want to make sure I eat right and don't just use carbo-loading as a hall pass to have cake every day. So I consulted Jena Brown, a sports dietitian specializing in endurance racing, who reviewed my plan for the week and suggested improvements.

She told me I should aim for roughly 8-12 grams of carbs a day per kilogram of my body weight. Not eating enough carbs before the race can impact my physical and mental performance — she said I will get tired sooner, have reduced endurance, and will feel like I'm working harder than I actually am.

We did a calculation, and I should be aiming for 508 grams of carbs every day, broken down as 169 grams for three meals and 85 grams for six.

The kinds of carbs I eat — as well as the foods I pair them with — are also crucial.

Focus on lean protein with more carbs

Brown said eating protein, ideally from whole, unprocessed foods, is also highly important for athletic performance.

My go-to breakfast is peanut butter oatmeal. I use one cup of oatmeal (103g carbs and 26g protein), a scoop of peanut butter (8g protein), and some berries (10g carbs).

Brown said this was a great choice because the oats provide protein in addition to carbs, while the berries add a few more carbs and have extra nutritional value.

For meal-prep, I made salmon and pasta in a butter-tomato sauce — a variation of a New York Times recipe — with roughly 54g protein and 64g carbs.

I spoke to Brown on Tuesday, and she had one note for this dish: I stuck to whole-wheat pasta (my usual go-to) when regular pasta made with refined flour would be better for my pre-marathon digestion. (Regular pasta has just as much protein and carbs as whole wheat).

Brown explained that because of the volume of carbs I'll need to eat, consuming those higher in fiber (like Ezekiel bread, my other favorite) will result in bloating and discomfort.

Luckily, because I made this at the start of the week, I was still in the clear: Brown said the last three days of carbo-loading matter the most.

I should consume more than half my body weight in fluids

Drinking enough water is always important, but Brown said to ramp up my intake even more this week. "You need extra fluid to store those carbohydrates in your muscles," she said. At the same time, you don't want to overdo it and dilute your sodium or electrolyte levels — both are very important for your running performance.

She said that normally, your bare minimum of fluids — including things like coffee, juice, or milk — should be half your body weight in ounces. This week, you should add 20 or 30 more ounces of water per day, so I should be aiming for 90-100 ounces total.

Brown said smoothies are "fantastic" because they're hydrating and also include electrolytes. After my shorter runs this week, I got a berry smoothie with 55g carbs and 27g protein (from protein powder).

The rest of the time, I've been setting reminders to drink more water and trying to get as much of it as I can, such as ordering a jumbo-sized seltzer at the movies.

Cut down on fiber, fat, and spice

In the last three days, Brown said it's good to not go above the minimum recommended fiber and fat recommendations (no more than 25g fiber for women and 38g fiber for men, and not going over 0.45g fat per pound of bodyweight, 63g for me).

Pasta is great, but pasta covered in cheese or served with a side of broccoli can contribute to digestion problems and sluggishness.

I remember one of the best runs I ever had was the day after I ate cottage cheese pasta, which is low in fat and high in protein and carbs — a half-cup of cottage cheese is 14g of protein, while a package of cooked pasta is about 111g of carbs. I've meal-prepped it for the rest of the week.

Then came the question I was most curious about: what's the best thing to eat the night before? I ask because I often get "runner's trots" on long runs and want to avoid the fate of so many past marathon runners. I'm hoping to give my sensitive stomach the best shot at not making me a national headline.

Brown said to avoid spicy food or anything too rich. The best meals would be pasta in a tomato sauce or a baked potato, light on toppings. On the morning of the marathon, I'll want to stick to simple carbs and sugars that are easier to digest quickly, like a plain bagel and some Gatorade.

Carbo-loading didn't end up being as thrilling as I thought. I daydreamed about going all out at an Ethiopian restaurant or challenging how many rolls an all-you-can-eat sushi place is willing to serve me.

Brown said the temptation to have a fancy, celebratory dinner before the race is normal. But she recommended either making food at home or looking at the menu ahead of time (rather than excitedly making a game-time decision).

My friend booked us a table at a ramen spot for the night before. I will follow Brown's advice and order a lighter vegan broth with noodles and seaweed instead of the cheese-and-chili-oil pizza-fusion option my heart longs for.

On the bright side, she said decadent meals are totally fine after the marathon. That's all the motivation I need to cross that finish line.