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Nutrition Beta, Part 2: Fueling to Climb Longer and Stronger

If you want next-level performance, you need to power your body with the right kind of food. Don’t be stupid: Under-fueling can be dangerous.

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It was my first time climbing outdoors at Smith Rock State Park in Oregon. I am about 60 feet up on a 5.9 and am shaky and weak. I didn’t eat enough during the day. If I weren’t too freaked out to release my white-knuckle grip from the rock to slap my palm to my forehead (duh!), I would have. As a sports dietitian, I should have known better.  

In a sport where safety is priority and a mistake can mean injury or death, fueling and hydrating properly is crucial during all-day climbs, multi-pitch climbs, and multiple-day climbing trips. If you want next-level performance, you need to power your body with the right kind of food.  Don’t be stupid. Under-fueling can be dangerous.

Climbers burn on average about 10-11 calories per minute of active climbing. You can burn about 200 calories total for 60 minutes of climbing/belaying. And you can burn up to 1200 calories for a four-hour climbing session if you have to hike in and carry gear. That’s as much as some people burn running a half-marathon!

Your body uses both carbohydrate and fat as fuel while climbing. Your muscles use glycogen, which is a storage form of sugar. If you run out of glycogen, you’ll hit the wall. And I’m not talking about a whipper (although that could happen too…). This is a metabolic bonk where you completely run out of energy. You feel weak, heavy, and shaky. To avoid this, eat during your climb session to keep blood sugar supply up and spare glycogen as much as possible.

Carbohydrates paired with protein to a better job keeping your energy level stable for longer climbs. To keep you fueled for climbing more than three hours, have small snacks every one to two hours of both protein and carbohydrate. Try things like:

Trail mix

Dried fruit


Fruit leather 

Nut butter pouches

Gummy bears

Pepperoni sticks

Cheese sticks

Chocolate milk

Hard boiled eggs

Peanut butter and jelly sandwich

Bars (e.g., KIND, Clif, Larabar, Picky Bars)

Pretzels with Peanut Butter/Humus

Mmmmm jerky.

Only bring what you enjoy eating. A climbing guide once told me he sees people bringing bars, energy drinks, and food they’ve never tried on trips. This is a recipe for disaster. If you don’t like it, you won’t eat it. You’ll then lack the energy to climb well. Or, you may eat it and then have a fun digestive surprise on your trip. Either way, it’s a losing situation.

Ok, so a word about hydration. This is key. It takes about 20-40 minutes to recover from low blood sugar, but it can take all day to recover from dehydration. Here’s how to avoid it.

Drink when you’re thirsty. You can use water or a sports drink. Be smart. If it is hot or windy, you’ll need more fluids than usual. It’s a fine balance between dehydration, hydrating correctly, and over-hydration. A sloshy stomach can interfere with sending the project, but so can dehydration. A good rule of thumb is eight ounces per hour. You may need more or less than this, depending on your weight and the environment and temperature.

Watch your pee. Dark, concentrated urine means you need to drink more. Clear urine and frequent urination means you are drinking a bit too much.  Your goal is light lemonade or straw color urine.

At high altitude, your body demands more carbohydrate and more fluids. Keep this in mind if you are more than 2600 meters (8600 feet) above sea level. Be in tune to how your body feels. Take a break or call it quits if you feel dizzy, nauseated, weak, shaky, or you lose mental sharpness.

Symptoms of dehydration include: increased thirst, dry mouth, dark urine, dizziness, foggy mind, and fatigue. This is a dangerous condition that needs immediate treatment.

A new tactic endurance athletes use is called carbohydrate mouth rinse. This is un-tested and un-researched in rock climbers, but it may be useful in certain situations. It’s a specific strategy where you drink a bit of sports drink, swish it around in your mouth, and spit it out (don’t swallow).

Why would someone do this? If you feel like you’re already pretty hydrated and you want to avoid a heavy stomach, but at the same time you feel like you need some fuel to keep you going. If you’re climbing a route that requires you to contort like a master yogi, try the swish and spit.

The act of rinsing out your mouth with something sugary sends a signal to your brain which makes it think it’s receiving food. In endurance athletes, this mouth rinse has helped them improve their time to exhaustion and rate of perceived exertion. This can translate into going longer and stronger when climbing.

Carbohydrate mouth rinse isn’t for everyone, and not all situations need it. Mostly it’s best to just eat and drink. But keep the mouth rinse in mind if you are hydrated and want to avoid over-hydration (called hyponatremia). This is a dangerous medical condition that needs immediate treatment. Symptoms include dizziness, nausea, confusion, headache, and fatigue.

The take-home message: If you follow some simple fueling and hydrating strategies, you’ll set yourself up for success to send your project. Avoid the face palm moment. Plan your fueling strategy ahead of time and bring enough fuel and fluid to keep you going.

Up next:

Nutrition Beta, Part 3: Recovery nutrition to maximize training gains


Nutrition Beta, Part 1: Easy snacks to crush the route 

Marisa Michael, RDN, LD is a sports dietitian and personal trainer. She helps athletes and active people eat better for sports performance and health. She has conducted original research on adolescent rock climbing nutrition. You can find her at to book a virtual nutrition consultation. Follow her on Instagram @realnutritiondietitian for nutrition and fitness tips. Michael is in the middle of writing a book on rock climbing nutrition and she wants to hear from you. If you have nutrition questions, tips, stories, or favorite foods to share, drop her a line at dietitian[at]