How many gels for a half marathon? Fueling, timing and why

How many gels for a half marathon? For most people finishing somewhere around two hours, two to four, depending on how many carbs each gel has and whether you're also drinking a sports drink. Faster runners need fewer. Slower runners need more. Anyone who has never taken a gel while running needs to practice before race day, not on it.

That answer comes from one guideline, a bit of arithmetic and a lot of testing. Here's all three, plus when to take them and what to do if your stomach objects. If your half build also includes a squat rack, a Runna-style plan that doesn't ignore the gym keeps the long runs, where you practice all this, away from heavy leg days.

One note first: this is general practice, not a personal nutrition prescription. If you have diabetes, a GI condition or anything else clinical, talk to a doctor or a registered dietitian before changing how you fuel.

How many gels for a half marathon: the guideline

The joint position stand from the Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Sports Medicine gives a target of 30 to 60 g of carbohydrate per hour for sustained exercise lasting 1 to 2.5 hours, and up to 90 g per hour beyond about 2.5 to 3 hours (Thomas, Erdman and Burke, 2016). Burke et al., 2011 describe the same 30 to 60 g per hour for longer events, with up to 90 g per hour for events over 2.5 hours using products that blend different carbohydrate types.

Most half marathons land between one and two and a half hours. So for most people, the number is 30 to 60 g of carbs per hour.

Gels vary a lot by brand, so check the label for grams of carbohydrate per gel. Then it's division. If you're following a 12-week half plan, your long runs are where you work out which gel, how many, and how your stomach feels about it. For the training side of the build, this breakdown of how to train for a half marathon covers everything except the snacks.

How many energy gels for a half marathon, by finish time

Here's the arithmetic for a gel with 25 g of carbs. If yours has a different amount, redo the sums with your number.

Three things make the real number lower than the table:

• ›Sports drink counts. If you drink a cup at every aid station, that's carbohydrate too. Check what your race serves and how much carbohydrate it contains.
• ›Your pre-race breakfast counts. A proper carb breakfast means you don't need to start eating at the start line.
• ›Most runners start partway in. The usual practice is a first gel somewhere around 30 to 45 minutes, then every 20 to 40 minutes after that.

And one thing makes it higher: if you're out there beyond about 2.5 to 3 hours, the guideline goes up to as much as 90 g per hour (Thomas, Erdman and Burke, 2016). That top end is something you train your gut up to, not something you try for the first time on race day.

If you're not sure where you'll finish, our guide to average half marathon time has the middle of the field, and your own recent races will tell you more.

When to take gels during a half marathon

A simple schedule most runners can start with:

• ›Before the start: nothing extra if you've eaten breakfast. Some people take a gel 10 to 15 minutes before the gun. Try it in training first.
• ›First gel: around 30 to 45 minutes in.
• ›Then: every 20 to 40 minutes, depending on your target grams per hour.
• ›Last gel: not in the final 15 to 20 minutes. You won't use it before the finish, and your stomach will be busy enough.

A two-hour runner aiming for about 45 g per hour with 25 g gels might take one at 35 minutes, one at 70 and one at 100. That's three gels and roughly 75 g of carbs, plus whatever sports drink they pick up. Sensible, testable, boring.

Take gels with water if you can. Most aid stations have it. Planning gels around the water stops on the course map saves you from swallowing a thick gel dry at mile seven.

Your gel timing also depends on your pace. Going out too fast makes everything harder, including your stomach. Race pace explained covers picking a pace you can hold, which is the other half of fueling well.

Gels, chews or drink?

It doesn't matter much where the carbs come from. It matters that you get them in and that your stomach is used to them.

Mixing works. Plenty of runners use a gel or two plus sports drink at aid stations. Just know your rough total.

Practice in training, not on race day

The single biggest fueling mistake is trying something new on race day. Your long runs exist so race day holds no surprises.

• ›Use the exact gel you'll race with. Same brand, same flavor, same caffeine or not.
• ›Practice at race timing on long runs over an hour.
• ›Start at the bottom of the range (around 30 g per hour) and build if your stomach is happy.
• ›Practice taking them at pace at least a few times. Swallowing at an easy jog and at race pace are different experiences.
• ›Note what happened. Cramps, sloshing, needing a bathroom, energy dips. Adjust next time.

If you're coming in from scratch on a short build, like couch to half marathon in 12 weeks, the long runs will be shorter and fewer, which leaves fewer chances to test. Start practicing gels as soon as your long runs pass an hour.

What to eat before the race

What you eat before matters as much as what you take during. The position stand's pre-event guideline is 1 to 4 g of carbohydrate per kilogram of body weight, 1 to 4 hours before exercise longer than an hour (Thomas, Erdman and Burke, 2016). In practice, that's a carb-heavy breakfast you've eaten before your long runs: oats, toast with honey, a bagel, a banana.

The same rules carry over from training, so what to eat before a long run explained is essentially your race-morning plan, eaten a little earlier to allow for travel and queues.

Half vs full: why the marathon is different

A half marathon is long enough that fueling helps most people, and short enough that a mistake usually means a slower finish rather than a disaster. The marathon is different. Fueling becomes a skill you practice over months, and the top of the carbs-per-hour range comes into play for more runners. Energy gels for marathon training follow the same idea: test early, build up gradually, never improvise.

After the finish

Fueling doesn't stop at the line. Eat something with carbs and protein once your stomach settles, drink, and eat proper meals for the next few days. What to eat after half marathon day is mostly normal food, just enough of it. Then let the legs rest: half marathon recovery is mostly easy movement, food and sleep for a few days before anything hard.

Common mistakes

• ›Taking zero gels for a two-hour race "because it's only a half". It's two hours. Fuel it.
• ›Taking six gels in the first hour because you panicked. Stomachs have opinions.
• ›Using the free gel from the expo for the first time on race day. No.
• ›Forgetting the sports drink counts. You might be doubling up without knowing it.
• ›Swallowing gels with no water. Plan them near aid stations.

How exrsz handles this

exrsz builds a periodized plan from your goal, your schedule, your level and your equipment, with running and lifting in one plan, so your long runs, where you practice fueling, land on fresh legs. It adapts each week to how you trained and reshuffles missed sessions. Which gel flavor you choose is still your problem.

FAQ

How many gels for a half marathon do I need?

Most runners finishing around two hours take two to four gels, depending on the carbs per gel and any sports drink. The guideline from the ACSM, Academy of Nutrition and Dietetics and Dietitians of Canada position stand is 30 to 60 g of carbohydrate per hour for efforts of 1 to 2.5 hours (Thomas, Erdman and Burke, 2016).

How many energy gels for a half marathon if I'm running 2:30 or slower?

Usually three to six, depending on the gel and how much sports drink you take. If you'll be out there beyond about 2.5 to 3 hours, guidelines allow up to 90 g of carbs per hour, but only if you've built up to it in training (Thomas, Erdman and Burke, 2016).

When should I take my first gel in a half marathon?

Most runners take the first one around 30 to 45 minutes in, then one every 20 to 40 minutes. Avoid taking one in the last 15 to 20 minutes.

Do I need gels for a half marathon at all?

If you'll be running longer than about an hour, carbohydrate during the race usually helps, and gels are an easy way to get it. Sports drink or familiar food works too, as long as you've practiced it on long runs.

Should I take gels with water?

Yes, if you can. Most gels are easier to get down with water, so plan them near the aid stations on your course.