How to Fuel Long Runs and Races: How Many Gels, When to Take Them, and What I Use

I've bonked in a race, and I know exactly why it happened.

It was the Dam to DSM Half Marathon. I went out at close to my 10K PR pace, had no real fueling plan, and didn't pay much attention to fluids or electrolytes. The back half of that race was miserable. My legs went heavy, my pace fell apart, and there was nothing I could do about it.

A few months later, I ran the Des Moines Marathon with a plan. I knew which gels I was taking and roughly when. I knew what I'd drink at every aid station, and I'd practiced all of it on my long runs. I finished in 3:33, a 19-minute PR, and never hit the wall.

The difference wasn't just the gels. I paced myself better, practiced my fueling, and had a plan for fluids and sodium, too. You can read the full race story in how I ran a 19-minute marathon PR at 44.

Fueling won't make you faster than your training. But bad fueling can easily make you slower than your training. Here's how to get it right.

Why You Need to Fuel at All

Your body stores carbohydrate as glycogen in your muscles and liver. It's your main fuel source at moderate and hard running efforts, and you can only store a limited amount. For many runners, that's enough for roughly 90 minutes to 2 hours of hard running, but it varies a lot with how hard you're running, your training, your diet, and your body.

When those stores run low, your body has to rely more on fat, which it can't burn fast enough to hold your pace. That's the bonk, or "hitting the wall." Your legs feel heavy, your pace drops, and sometimes your thinking gets foggy too.

Taking in carbs during the run doesn't stop you from using glycogen. It gives your body another source of fuel so your stores last longer. The goal is to keep carbs available all the way to the finish and lower your risk of a late-race crash.

How Many Carbs Do You Need Per Hour?

The most useful way to think about fueling is grams of carbohydrate per hour, not number of gels. Most gels have somewhere between 20 and 30 grams of carbs, so "two gels" can mean very different things depending on the brand.

Sports nutrition researcher Asker Jeukendrup's widely used guidelines (published in Sports Medicine in 2014) scale carb intake with how long you're out there:

Those upper numbers are a ceiling, not a requirement. Going above 60 grams an hour works best with gels that combine different types of sugar (like glucose and fructose) and a gut that's been trained to handle it. If your stomach isn't used to it, cramming in 90 grams an hour is a good way to spend part of your race looking for a porta-potty.

Here's what I actually did in Des Moines. I took five gels, which added up to a little under 120 grams of carbs over 3 hours and 33 minutes. That's a little over 30 grams an hour from gels alone. I also drank Powerade at the aid stations where I didn't take a gel, which pushed my total higher. It was a moderate amount, and I never bonked.

If you want a number built for you, our fueling calculator sets your carbs per hour based on how trained your gut is, then turns it into a gel plan for your race or long run.

When to Take Your Gels

The biggest timing mistake is waiting until you feel like you need it. By the time you feel low on energy, you're already behind, and it's hard to catch up.

For longer runs and races, a good starting point is:

• Start early. For a run lasting longer than about 60 to 75 minutes, consider starting your fueling within the first 30 to 45 minutes, depending on your target intake and what you've practiced. Don't wait for the first sign of fatigue.
• Spread your carbs throughout the run. Many runners take a gel every 30 to 40 minutes, but adjust the timing to how many carbs are in each gel and any sports drink you're having. Set a watch alert if you need a reminder. It's easy to forget once you're locked into a pace.
• Keep fueling toward the finish if it fits your plan. You don't need to automatically skip your last gel. Whether it helps depends on your timing, your total intake, and how long you have left to run.

The goal is a steady supply of carbs, not a gel schedule that ignores everything else you're eating and drinking. Taking a few gels close together after you've fallen behind usually leads to a sloshy stomach, not a comeback.

Sample Half and Full Marathon Fueling Plans

These examples use gels with roughly 22 to 25 grams of carbs, with the first around 30 to 40 minutes in and the rest spaced every 30 to 40 minutes. Depending on the gel and the spacing, that's about 33 to 50 grams of carbs an hour. The totals are approximate and don't include sports drink. Adjust the number of gels based on your target carb intake, your finish time, what your stomach tolerates, and how many carbs you're getting from other sources.

These plans are starting points, not exact prescriptions. Five gels in a 3:30 marathon works for some runners, while others need more. Your total carb intake includes sports drinks and any other fuel you take in, so adjust your gel schedule to account for those sources. If your gut handles more, you can fuel on the higher end or add sports drink at aid stations like I did. If you're new to fueling, start on the lower end and build up during your training.

Look at the course map before race day, too. Plan your gels to land just before an aid station so you can wash them down with water. For Des Moines specifically, our Des Moines Marathon guide covers the course and aid stations.

Practice Your Fueling (and Train Your Gut)

The oldest rule in race fueling still holds up: never try anything new on race day. Not a new gel, not a new flavor, not the free sample from the expo.

Your long runs are where you figure this out. Use the gels you plan to race with, at the times you plan to take them, with the drinks you plan to have. I don't normally use GU in training, but I used it on a few long runs before the marathon because I knew I'd be racing with it. By race day, nothing was new.

Practice also changes how much your stomach can handle. In research from Ricardo Costa's lab at Monash University (published in 2017 and 2018), runners who practiced taking carbs during runs every day for two weeks reported fewer gut symptoms than a placebo group, absorbed carbs better, and performed better in a running test afterward. Those were small lab studies, so the exact results won't carry over to every runner, but the takeaway is clear: practice your fueling in training, especially if you want to take in more carbs.

I'm lucky here. I've never had stomach problems with gels or drinks, and I didn't do a formal gut-training program. I just followed the recommended amounts for how long I was running and used my long runs as practice. But if gels tend to bother you, or you want to fuel on the higher end, building up gradually over your training block is worth the effort.

Water, Sports Drinks, and Aid Stations

Gels are concentrated. Take them with water, not on their own. A few sips right after a gel helps it go down and helps your stomach handle it.

Here's the system I used in the marathon:

• At aid stations where I took a gel, I drank water.
• At aid stations where I didn't take a gel, I drank Powerade.

That kept a steady stream of carbs and electrolytes coming in without stacking a gel and a sugary drink on top of each other. Some runners can handle both at once, but water with gels is the safer default, especially if you haven't practiced the combination.

On long training runs where water isn't easy to find, drink gels can help bridge the gap. They have more water mixed in, so they're easier to get down without a separate drink. I've had good results with Amacx Energy Drink Gel. It isn't a replacement for actually drinking, but it helps between water stops. View drink gels on Amazon. If you need a better way to carry water, our guide to hydration vests, belts, and handhelds breaks down your options.

Don't Forget Electrolytes

Carbs keep you moving. Sodium helps keep you from falling apart in a different way. You lose a lot of it through sweat, and on long, hot runs that loss adds up.

Electrolytes won't prevent a bonk. That comes down to pacing and carbs. But sodium and fluids matter for replacing what you sweat out, and I didn't have a plan for them at Dam to DSM. For the marathon, every gel I took had at least some sodium, and a few of them had extra. The salted caramel GUs have about 125 milligrams of sodium each, and Honey Stinger's electrolyte gels have about 100 milligrams, roughly double their classic version. Between those gels and the Powerade, I was getting sodium the whole way.

For how much sodium you need, how sweat rate and weather change it, and whether you need potassium and magnesium too, read our full guide to electrolytes for long runs. On hot days, check out running in the heat as well.

Caffeine Gels

Caffeine is one of the best-researched legal performance boosters in endurance sports. The International Society of Sports Nutrition's 2021 position stand found that it consistently improves performance at doses of about 3 to 6 milligrams per kilogram of body weight, with endurance exercise showing some of the most consistent benefits. It can make the same pace feel easier.

Most caffeinated gels are well below those research doses. A caffeinated GU has 20 or 40 milligrams, depending on the flavor. So a caffeine gel is more of a small boost than a magic switch, especially if you already had coffee that morning.

How I use them:

• On long runs, I usually take one caffeinated gel in the back half.
• In the marathon, I took two. Both were salted caramel GUs, which have 20 milligrams of caffeine each.

Those two gels gave me 40 milligrams of caffeine total, which is well below the doses commonly studied for performance benefits. I take them because they fit my routine, but I wouldn't assume that amount will give everyone a noticeable boost.

Caffeine takes a while to kick in, so take it a bit before you want to feel it rather than waiting until you're already struggling. And like everything else, try it in training first. Caffeine affects people differently, and some runners find it upsets their stomach or makes them jittery. If you're sensitive to it, or you're not a regular caffeine user, start low.

What to Eat Before a Long Run

Fueling starts before you leave the house. Before my long runs, I keep it simple: a banana, some toast, and electrolytes. It's easy on my stomach and gives me some carbs to start the run with.

The exact food matters less than whether it works for you. Stick to something simple, familiar, and not too heavy, and give yourself time to digest before you start.

For race week, your fueling starts even earlier. Our 24 to 36 hour fuel window guide covers carb loading in the days before a race, and race morning execution covers breakfast timing on race day.

The Gels I Use

There's no single best gel. The best one is the one your stomach likes that you'll actually take on schedule. Here's what I've used and what I think of each.

Honey Stinger Organic Energy Gels. These have become my go-to for long runs. They're organic, made with honey, and easy to find at most running stores. The classic gels have 24 grams of carbs and around 50 milligrams of sodium, though it can vary a little by flavor. The electrolyte gels also have 24 grams of carbs but bump the sodium to about 100 milligrams and add potassium, which is why I like them for longer and hotter runs. They come in several flavors, so it's easy to find one you like.

HNY+ Organic Honey Gels. Honestly, I like these a little more than Honey Stinger. They're also honey-based, with about 22 grams of carbs (check the packet, since it can vary by flavor), added electrolytes, and caffeinated versions for later in a race. The only reason they aren't my go-to is that they're harder to find. If you can get them, they're worth trying. Available on Amazon.

GU Energy Gels. GU is the classic, and it's what I used for two of my five gels in the marathon. They use maltodextrin and fructose, have about 21 to 23 grams of carbs, and come in caffeinated and caffeine-free flavors. The salted caramel is a good race-day pick because it has extra sodium and a little caffeine. I don't use GU much in regular training. I try to keep added sugar down in my everyday diet, so I lean toward the honey- and maple-based gels most of the time. (To be clear, every gel is mostly sugar. That's the point of them. I just prefer the simpler ingredient lists.)

BPN Go Gels. A solid option if you want a clean ingredient list. Each one has 24 grams of carbs, and they're vegan and gluten-free. I used one of these in the marathon, too. Check it out on Amazon.

UnTapped Maple Syrup Packets. These are pure maple syrup in a single-serve packet. They're thinner than most gels, which makes them easy to take mid-run. I've used them a lot in the past, and I'll probably go back to them. Some versions have caffeine. Find them on Amazon.

Precision Fuel PF30. If you want more carbs per packet, PF30 has 30 grams, using a 2:1 mix of maltodextrin to fructose. That makes it easier to hit higher carb targets with fewer gels, but only if your gut is trained for it. The flavor is mild, which some runners prefer. Check prices on Amazon.

Why Runners Bonk

When a runner falls apart late in a half or full marathon, a few common culprits are:

1. They started too fast. Going out too hard burns through glycogen faster, and no amount of gels fully makes up for it. That was a big part of my Dam to DSM bonk.
2. They fueled too late or too little. Waiting until you feel bad means you're already behind.
3. They tried something new on race day. A new gel, a new drink, or a new amount that their stomach wasn't ready for.

Heat, dehydration, illness, and built-up fatigue can play a part too. But these three are the ones you can fix in training. Run your long runs at the right pace (our article on why the long run is not a race covers that), practice your fueling on them, and show up on race day with a plan you've already done a dozen times.

FAQ

How many gels should I take during a marathon? Many runners take one gel every 30 to 40 minutes, which often means 4 to 9 gels depending on finish time, how many carbs are in each gel, and how much sports drink you're having. I took five gels in 3:33 and drank Powerade at the aid stations where I didn't take a gel. Our fueling calculator can build a plan for your pace.

How many gels should I take during a half marathon? Usually 1 to 4, depending on how long you'll be out there. A 2-hour half marathoner might take 2 or 3.

When should I take my first gel? For runs longer than about 60 to 75 minutes, many runners start within the first 30 to 45 minutes, before they feel like they need it.

How many carbs per hour should I take in while running? About 30 grams an hour for runs of 1 to 2 hours, up to about 60 grams for runs of 2 to 2.5 hours, and up to about 90 grams for longer efforts if your gut is trained for it.

Do I need gels for a 10-mile long run? If your 10-mile run takes longer than about an hour, taking in some carbs can help support your effort and gives you a chance to practice your race-day fueling. For shorter runs, most runners can get by without fuel during the run, especially if they've eaten beforehand.

Should I take gels with water or sports drink? Water is the safer choice. I take gels with water and drink sports drink at the aid stations where I'm not taking a gel.

When should I take a caffeine gel? Most runners save them for the second half of a long run or race. Caffeine takes a while to kick in, so take it a bit before you need it, and test it in training first.

What should I eat before a long run? Something simple and familiar. I have a banana, some toast, and electrolytes.

---

This article is for general information and isn't medical advice. If you have a medical condition, such as diabetes, or you have ongoing stomach problems when you run, talk to your doctor or a registered dietitian before changing how you fuel.

This article contains affiliate links. If you purchase through them, we earn a small commission at no extra cost to you.

Sources

• Jeukendrup, A. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine, 44(Suppl 1), S25–S33.
• Costa, R. J. S., et al. (2017). Gut-training: the impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance. Applied Physiology, Nutrition, and Metabolism, 42(5), 547–557.
• Miall, A., et al. (2018). Two weeks of repetitive gut-challenge reduce exercise-associated gastrointestinal symptoms and malabsorption. Scandinavian Journal of Medicine & Science in Sports, 28(2), 630–640.
• Guest, N. S., et al. (2021). International Society of Sports Nutrition position stand: caffeine and exercise performance. Journal of the International Society of Sports Nutrition, 18(1), 1.

Get a fueling plan for your next race with our fueling calculator, and build your free personalized training plan from your actual fitness. Build your plan now.