Energy bars for rock climbing: what to eat on a climbing day
In this guide
Quick answer: A full multi-pitch day can burn 3,000 to 4,000 calories and a long alpine day over 5,000, so the best climbing food packs a lot of calories into something you can eat a few bites at a time at a belay. Dense bars, nuts, flapjack and chocolate do this best; for an indoor or short crag session, a normal meal beforehand and one snack is usually enough.
Written by James Frost, founder of Flaming Phoenix and the maker of Phoenix Bars. Updated November 2026.
This page covers why most climbing snacks run short on calories, what climbers need from food, and how dense high calorie bars compare with the alternatives.
Why most climbing food falls short
Climbers face a specific nutritional constraint that most sports do not: you eat in short windows, often in awkward positions, and everything you carry competes for space with gear that keeps you alive.
Most climbers default to cereal bars, flapjacks, nuts, or gels. These work, but the maths rarely adds up. A typical cereal bar weighs 35 to 45g and delivers 130 to 180 calories. If you are on a full day of multi-pitch climbing burning 3,000 to 4,000 calories, you would need to carry and eat 17 to 30 of those bars to replace what you are burning. Nobody does that. Instead, most climbers finish the day in a significant calorie deficit, which builds up across multi-day trips and shows up as slower recovery and poorer decisions late in the day.
The real constraint is calories per mouthful: most climbing snacks come in small portions, so what climbers actually eat at belays adds up to far less than they burn.
How do common climbing snacks compare?
These are typical UK supermarket values, rounded, so check the labels on what you buy.
| Food | Typical portion | Calories (approx.) | Calories per gram (approx.) |
|---|---|---|---|
| Mixed nuts | 50g bag | 305 | 6.1 |
| Milk chocolate | 45g bar | 240 | 5.3 |
| Flapjack | 80g slice | 370 | 4.6 |
| Cereal bar | 40g bar | 160 | 4.0 |
| Protein bar | 60g bar | 225 | 3.8 |
| Jelly sweets | 50g handful | 170 | 3.4 |
| Energy gel | 1 sachet (40 to 60g) | 90 to 100 | 1.5 to 2.5 |
| Banana | 1 medium, peeled (about 100g) | 95 | 1.0 |
Nuts and chocolate are the densest by weight, but chocolate softens on hot rock and loose nuts are awkward on a hanging stance. Cereal bars, gels and bananas are easy to eat but light on calories per item, which is why the total climbs so slowly over a day.
What do climbers need from food?
I have spoken with sport, trad and alpine climbers, and the requirements barely change.
Maximum calories in minimum weight and volume. On trad and alpine routes, your rack, rope, protection, and emergency kit already fill your pack. Food needs to earn its space with plenty of calories and little bulk. The benchmark most climbers use instinctively is calories per gram. Anything below 4.0 cal/g is taking up space that could go to something more efficient.
Edible in small amounts over time. You rarely sit down for a meal on a climb. You eat a few bites at a belay, a piece on a ledge, a mouthful while your partner leads. Food needs to be something you can break apart, eat a piece of, put back in your pocket, and return to an hour later. Gels do not work this way. Neither do sandwiches.
Stable in all conditions. Rock gets hot. Alpine routes get cold. A bar that melts on sun-baked limestone in the Verdon Gorge is useless, and a bar that freezes solid on a Scottish winter route is equally useless. Climbers need food that holds its form across a wide temperature range.
Not sickly sweet. Palate fatigue is real on long days. Most energy gels and many bars are intensely sweet, which becomes nauseating after several hours of physical effort. Climbers consistently prefer food with a savoury or neutral flavour profile that they can eat repeatedly without their stomach turning.
No complicated packaging. You need to be able to open it with one hand or with gloves on. It cannot leave sticky residue on your fingers before you grab the next hold.
How many calories does rock climbing burn?
Actually moving on rock burns about 420 calories an hour for a 72kg climber at a moderate grade, but most of a climbing day is spent belaying, resting and walking, so the average is much lower. The table uses the same method as our climbing calorie calculator: Compendium of Physical Activities values of 5.8 METs for moderate climbing, 8 for an alpine day and 1.8 for time between goes, for a 72kg climber. The figures include what you would burn at rest anyway and are rounded to the nearest 10, so treat them as approximate.
| Type of climbing day | Time out | Share spent climbing | Calories per hour (approx.) | Session total (approx.) |
|---|---|---|---|---|
| Indoor or bouldering session | 2 hours | About a third | 230 | 460 |
| Single-pitch sport day at the crag | 5 hours | About a third | 230 | 1,150 |
| Multi-pitch trad day | 8 hours | About half | 270 | 2,190 |
| Alpine day | 10 hours | About 85% | 510 | 5,090 |
Add the rest of the day, including sleep, and the multi-pitch climber's total comes to roughly 3,600 calories, which is where the 3,000 to 4,000 figure for a full day comes from. A heavier climber, cold weather or a long walk-in pushes it higher.
What should you eat before and after climbing?
Eat a normal meal with plenty of carbohydrate two to three hours before you start, such as porridge, toast or a pasta lunch, and have a small snack 30 to 60 minutes before if you are hungry. Climbing on a full stomach feels heavy, so keep the last hour light. Afterwards, eat a proper meal with carbohydrate and protein within a couple of hours, which matters most when you are climbing again the next day.
Where Phoenix Bars fit
I make Phoenix Bars, so here is how they compare on the same measures. Each one carries up to 557 calories in a compact, 120g bar made with gluten-free oats. That is about 4.4 to 4.6 calories per gram, similar to a dense flapjack and above a typical protein bar, but the bigger difference is the size of each serving: one bar holds as many calories as three or four typical cereal bars. Our ranking of the best energy bars for expeditions compares named brands on the same measure.
Two Phoenix Bars weigh 240g and hold up to 1,114 calories. Matching that with typical 40g cereal bars at 130 to 180 calories each takes seven to nine bars, roughly 280 to 360g, and seven to nine wrappers to deal with on a ledge instead of two.
Customers have used them at both temperature extremes. On the Marathon des Sables, one runner found they kept their shape even in desert temperatures, and Matt Le Voi, who took 33 bars to climb Manaslu, said they don't freeze easily at cold temperatures.
Each bar breaks into quarters you can keep in a pocket, and there is no chocolate coating to melt onto your fingers on warm rock.
They come in six flavours (Vanilla, Cherry Bakewell, Chocolate, Salted Caramel, Ginger, and Apple & Cinnamon), none of them excessively sweet, so you can rotate them across a long day without palate fatigue.
Phoenix Bars: up to 557 calories per bar, £5.25. Buy Phoenix Bars
Each bar can also be crumbled into a mug and mixed with water to make a calorie-dense porridge. On multi-day alpine trips, this means your food doubles as both a climbing snack and a meal at camp, without carrying separate items for each.
How climbers use Phoenix Bars
For a single-pitch sport day, break one bar into quarters and keep them in a chalk bag pocket or jacket, then eat a piece between routes or during longer rests. One bar covers a four to six hour session alongside your normal meals.
On a multi-pitch trad day, carry two bars per person: one for the approach and climbing, one for the descent or as a reserve. Break them into pieces at the start and spread them between pockets so you can eat without digging into your pack.
On alpine routes, allow two to three bars a day: one mixed with water as porridge at the bivvy, and one or two carried on the route alongside other food, because a long alpine day burns far more than bars alone will cover.
For indoor climbing and training, one bar works as a snack before or after a session when you do not have time for a full meal, with up to 557 calories and up to 19g of protein.
Rated 4.9 out of 5 by customers
Phoenix Bars are rated 4.9 out of 5 from more than 390 customer reviews, including reviews from endurance athletes and expedition teams.
Try Phoenix Bars on your next climb
The easiest way to start is the 6-bar Short-Term Bundle, one of each flavour, so you can find the ones you like on a day out. At £5.25 a bar it costs £31.50, and one of each flavour adds up to 3,231 calories of climbing fuel.
If you already know they work for you, the 12-bar Starter Bundle (£63), 18-bar Essential Bundle (£94.50) or 36-bar Complete Bundle (£189) covers anything from a season of weekend climbing to a multi-day alpine trip.
International shipping available. Shelf life of up to two years, so you can keep them in your gear cupboard and grab a couple every time you head out.
Related guides
You may also find these useful:
High-altitude mountaineering nutrition - for alpine and expedition climbing above 3,000m
Hiking and trekking nutrition - for long approaches and multi-day treks
How to use Phoenix Bars - including the porridge method for meals at camp
Calorie-dense foods explained - what calories per gram means and how to compare foods
If you have any questions about using Phoenix Bars for climbing, feel free to get in touch directly.
James Frost
Founder, Flaming Phoenix
07990 519422
Sources: 2024 Adult Compendium of Physical Activities, sports; snack values from typical UK supermarket labels, rounded; Phoenix Bar values from our own pack labels.
Big calories. Small bar.
Up to 557 calories in a compact, lightweight bar of only 120g, with up to 66g of carbs and 19g of protein. Eat it whole, break it into pieces over a few hours, or mix it with water or milk for porridge.
Easy to eat, easy to digest and not sickly sweet. Customers have eaten them at -45°C and through the heat of the Marathon des Sables, and they keep for up to 2 years, so they work on a mountain, on a night shift, or at home on days when eating enough feels hard.
- 557 calories in only 120g (529 to 557 by flavour)
- 4.6 calories per gram
- 66g carbs per bar (up to)
- 19g protein per bar (up to)
