How should you be fueling for your long runs? How many carbs should you be eating? What about electrolytes and hydration? If you’ve ever bonked on a long run, come home feeling like a zombie, or hit the wall on race day—your fueling strategy (or lack of one) is probably to blame.
I’m Dr. Alyssa Olenick. I have a PhD in exercise physiology with a specialty in metabolism and sports nutrition—and I’ve run over 17 ultramarathons. I’ve also made just about every fueling mistake you can make along the way. So let me save you the trouble and break down exactly what you need to know about eating, drinking, and supplementing on your long runs.
“I don’t need to eat on my runs—I’m fat adapted and mostly burning fat at easy paces anyway.”
🚨 NOT SO FAST: Your body is crushing through carbs when you run—no matter your pace, zone, or how “fat adapted” you think you are.
Here’s the truth: I’ve looked at hundreds of metabolic exercise tests, and no matter how much fat someone thinks they’re burning, they are still using a significant amount of carbohydrate. It doesn’t matter if you’re running in zone 2 or at an easy pace. Your muscles need carbs, and neglecting that reality is one of the biggest performance mistakes runners make.
Runners will invest in the most expensive shoes, follow the perfect training program, nail every workout split—and then show up on race day and bonk because they didn’t eat enough carbs, drink enough water, or take in enough salt. My favorite saying applies here: fed is fast.
💡 KEY POINT:
The food you eat during your long runs is being used almost instantaneously—absorbed by your gut, delivered to your bloodstream, and sent to your muscles for energy. It isn’t making you fat. It isn’t making you slow. It’s literally keeping you running.
How much carbohydrate you need depends on the duration (and potentially intensity) of your run. Here are the general guidelines based on current sports nutrition recommendations:
📊 Carbohydrate Fueling by Run Duration:
Under 60 minutes → You likely don’t need carbs beyond what’s stored in your muscles. Water alone is usually fine.
60–90 minutes → Start with ~30–60 grams of carbs. You have glycogen stores to draw from, but a little fuel helps—especially for recovery and gut training.
1–2 hours → Aim for 30–60 grams of carbs per hour. Start on the lower end and build up over time as your gut adapts.
2–2.5+ hours → Shift toward 60–90 grams per hour—potentially even more if you can tolerate it. Elite ultrarunners at events like the 2025 Western States 100 were taking in over 100 grams per hour.
That 30 grams per hour is definitely the lower end of what’s currently recommended. The sports nutrition literature—and what we’re seeing elite athletes do in practice—is trending toward higher carbohydrate intake during endurance events. More doesn’t hurt if you can tolerate it, but it requires building up gradually.
💡 KEY POINT:
Personally, I bring a gel or a small bit of fuel on every run 60 minutes or longer—even when I might not “need” it. It helps with recovery, and it’s another opportunity to practice gut tolerance for race day. Nothing bad happens from bringing a little carb snack along.
Here’s one of my favorite ways to check: pay attention to how you feel after your long run.
If you come home feeling completely dead, unable to function, brain-fogged, and like you’d go absolutely feral if someone let you loose in a grocery store—that’s a sign you didn’t eat enough carbs during your run. You deserve a nap and some couch time after a long effort, but you shouldn’t feel like a zombie who’s completely useless to society for the rest of the day.
✅ On the runs where I crushed my carb intake—no matter how far or how long—I left feeling like I could actually make a rational decision about what to eat next, rather than the little gremlin voice inside me screaming for sugar and fried food.
There are tons of options, and it comes down to what works best for you:
Sports Nutrition Products:
Budget-Friendly & Real Food Options:
💡 KEY POINT:
If you’re pushing toward higher carb intake (70–90+ grams per hour), the commercially formulated sports nutrition products have an advantage: they use a specific glucose-to-fructose ratio that allows your gut to absorb two different types of carbohydrate simultaneously—meaning you can take in more without GI distress. Pure glucose or fructose alone hits a transport limit faster. So if you’re aiming high, complement your real food with gels, chews, or carb drinks.
Regardless of what distance you’re running or how fast you’re going, you want to rely primarily on carbohydrates for your mid-run fuel—not fats or protein. While there might be traces of those in ultra-distance foods, carbs are what your body is torching through, and that’s what it needs most.
Hydration is the second pillar of your fueling strategy—and it matters more than most runners think, especially those who skip the water bottle on cooler days.
📊 Hydration Guidelines for Running:
General target: ~4–8 ounces every 15–20 minutes during your run
Hourly benchmark: Roughly 16 ounces to 1 liter per hour (about one handheld bottle or soft flask)
Hot & humid conditions: You may need 1.5–2 bottles per hour—plan ahead and bring enough
Cold weather: You still need water. You’re still sweating and using water for energy metabolism, even if you don’t feel thirsty. If you’re running for an hour or more, always have water with you.
I personally prefer handhelds or soft flasks because they help you keep better track of how much you’re actually drinking compared to bladders in hydration packs. The key is being aware that you’re consistently drinking throughout your run—small sips every 15–20 minutes rather than chugging it all at once.
“I don’t need to bring water—it’s cold out and I’m not even sweating.”
🚨 MYTH BUSTED: Even in cold weather, dehydration can impair your performance, affect recovery, cause heart rate drift, and leave you feeling terrible post-run.
Don’t always wait to drink until you feel thirsty—by that point you might already be behind. But that doesn’t mean you need to chug water prematurely either. Think of it as staying consistently ahead of the curve with small, regular sips throughout your effort.
Electrolytes have gotten a lot of hype recently as a daily supplement, but as runners, we’re actually one of the populations that genuinely may need them—especially during long efforts.
📊 Electrolyte Guidelines:
Recreational runners (under 60 minutes): If you get enough sodium in your diet, you probably don’t need extra electrolytes during or around your runs.
Long runs, heavy sweaters, hot/humid conditions: Supplement with 300–1,000 mg of sodium per hour. That’s a wide range because individual needs vary significantly.
How to tell if you’re a salty sweater: If you can see or feel salt residue on your skin after sweating, you’re likely losing more sodium than average.
That 300–1,000 mg range is intentionally broad because electrolyte needs are highly individual. Cooler conditions usually mean you need less; hot and humid conditions push you toward the higher end. And just like carbohydrates, figuring out your sweet spot takes trial and error.
💡 KEY POINT:
Sometimes you can feel flat, bonky, or foggy on runs and assume it’s a carb issue—but if your carbs are dialed in and you’re still struggling, it might be a sodium issue. I personally went from about one Liquid IV per hour to 1,000 mg of sodium per hour on my long ultramarathon training runs—and the difference in how I felt and recovered was significant.
One important note: some symptoms of under-hydration and over-salting overlap, which makes this tricky to dial in. Headaches, fatigue, feeling “off”—these can point in either direction. It really does come down to experimenting during training runs and paying attention to how your body responds.
And here’s something a lot of people don’t talk about: the sugar in electrolyte products isn’t the enemy. A little sugar actually helps with the uptake of hydration and contributes to your hourly carb needs—both things we want as runners. Sugar is your friend when you’re active, especially on your long runs.
THE BOTTOM LINE
The three pillars of long run fueling are carbs, water, and electrolytes. How much of each you need depends on your duration, intensity, environment, and individual physiology—but the one universal truth is that you need to practice your nutrition in training so race day isn’t the first time you’re figuring it out. Fed is fast, and the runners who fuel well are the ones who finish strong.
Your Action Plan:
✓ Start fueling at 60 minutes – bring a gel or small carb source on every run an hour or longer, even if you don’t think you “need” it
✓ Build your carb intake gradually – start at 30g/hr and work up toward 60–90g/hr for longer efforts over weeks of training
✓ Hydrate consistently – aim for ~16 oz to 1 liter per hour in small sips every 15–20 minutes, and always bring water on runs over 60 minutes
✓ Dial in your electrolytes – start around 300 mg sodium/hr and increase toward 1,000 mg if you’re a heavy sweater, running long, or in hot conditions
✓ Practice everything in training – race day should never be the first time you try a gel, drink, or sodium amount
✓ Pay attention to your post-run state – if you’re a zombie afterward, you probably under-fueled; adjust and try more carbs next time
Want to Nail Your Running Nutrition?
Grab the free Cardio Essentials Guide for science-backed guidance on structuring your training and fueling your performance.
Ready to Train Smarter?
The Lyss Method is a science-based training program built for runners and athletes who want to perform better, recover smarter, and stop guessing with their nutrition and training.
Keywords: how to fuel long runs, long run nutrition, carbs for running, how many carbs per hour running, electrolytes for runners, hydration for runners, running fueling strategy, marathon nutrition, ultramarathon fueling, what to eat during long runs, running gels, running hydration plan, sodium for runners, sports nutrition for runners
I’m Exercise Physiologist, sports nutritionist, weight lifter, and ultra runner. I am here to bring science to your training in a no-nonsense way. I have helped thousands of women crush big lifting goals, cross race finish lines, and even do both. I’m here to help you do the same!
Get the free macro calculator
