So, You’re Running the Chicago Marathon

Don’t leave fueling to chance

The Chicago Marathon is a highlight of the marathon calendar and offers runners a perfect opportunity to achieve a PB. But, as always, the right fueling can be the difference between a PB and a DNF.

Hopefully, you’ve already been practicing your strategy and have a plan in place, but just in case, we’ve asked Jonah Rosner to put together a simple guide to race-day fueling.

Why do carbs help you hold your pace?

Your muscles use carbs and fat. Carbs provide more energy for the same amount of oxygen.
Stored carbs are limited. When they run low, holding your pace gets harder.
Carb loading, breakfast, and race fuel help keep carbs available.

Carb Loading: Your Target PER DAY

Start 36 to 48 hours before the race.

Aim for 10 g carbs per kg of body weight PER DAY

At 70 kg / 154 lb: 700 g of carbs each day.

Count carb grams, not food weight.

Spread across meals and snacks. Use a practiced plan.

Foods Perfect for Carb Loading

SOLID CARBS

White bread, bagels, white rice, plain pasta, low-fiber cereal, and jam.

LIQUID CARBS

Juice or carb drinks when solid food feels filling. The SiS BETA Fuel 80 is the perfect drink for this.

LIMIT THESE FOODS DURING YOUR CARB LOAD

Bran cereal, beans, big salads, fried foods, and creamy sauces. Avoid anything with lots of fiber or fat, as you could suffer stomach issues and end up feeling sluggish on race day.

Eat Breakfast!

2 to 3 hours before your start: 2 to 3 g of carbs per kg.

At 70 kg / 154 lb: 140 to 210 g of carbs.

EXAMPLE: ABOUT 175 g OF CARBS

Two plain bagels + two tablespoons of jam + a banana + 250 ml of juice.

Check portions and labels. Choose foods you have tested.

Caffeine is an option

Caffeine can make exercise feel easier.

A common range: 3 to 6 mg per kg, about 60 minutes before you start.

At 70 kg / 154 lb: 210 mg is the lower end.

Only use a dose you have tolerated in training. More is not automatically better.

Count caffeine from coffee, gels, and drinks together. Coffee’s caffeine content varies.

What to look for in a gel

Glucose and fructose are two types of sugar. Your gut takes them in through different routes.

Combining them can help you use more carbs than glucose alone, especially above 60 g/hour.

On the gel label, look for glucose or maltodextrin, plus fructose. The Science in Sport BETA Fuel range is perfect for a dual-source choice.

Turn your carb target into gel timing

During the race: 60 to 120 g of carbs/hour. Choose an amount you have practiced and tolerated in training.

Example: gels with 40 g of carbs each.

120 g/hour: for experienced runners who have practiced and tolerated it. More is not automatically better.

Make sure you’re counting your carb-based drinks in your count too!

80g of carbs per hour

One 40 g gel at each time, from your own start:

0:15 | 0:45 | 1:15 | 1:45

Continue every 30 minutes while racing.

Four-hour race: eight in-race gels, if gels provide all your carbs.

Use a practiced schedule. Include any pre-start gel and drink carbs in your plan.

Make sure you set your watch reminders before you start!