Nutrition for Trail Runners: The Complete Fuelling Guide

Trail runs have a habit of exposing gaps in your fuelling. One minute you feel light and springy, the next you’re battling heavy legs, brain fog, cramp or a sloshy stomach. Muddy climbs, long descents and changeable weather all raise the stakes, and the longer you’re out, the more a small mistake with food or drink can snowball.

The fix isn’t magic, it’s method. With a simple, evidence‑based plan—set by your distance, duration, intensity and terrain—you can keep energy steady, stay hydrated without overdoing it, avoid gut niggles and finish stronger. That means clear carbohydrate targets per hour, smart electrolytes, well‑timed meals, and practice so your gut is as trained as your legs.

This guide gives you the lot: how to define your run goals, set carb and hydration targets, plan pre‑run meals, choose on‑the‑move fuel (gels, drinks and real food), use caffeine wisely, troubleshoot common issues, adapt for heat, cold and altitude, organise aid stations/drop bags, match foods to your diet, recover well, carry it all comfortably, and follow sample plans by run length. Let’s build your personal fuelling strategy.

Step 1. Start with your goal: distance, duration, intensity and terrain

Before you think grams and gels, define the run you’re fuelling. Your energy, hydration and carry choices must fit the day. A steady two‑hour loop isn’t the same as a punchy, technical four‑hour mountain mission. Use this quick distance‑duration‑intensity‑terrain snapshot to anchor decisions—the foundation of effective nutrition for trail runners.

• Distance: Sets fuelling load; longer routes often mean carrying more food.
• Duration: Dictates timing; beyond 60–90 minutes, plan reliable in‑run carbs.
• Intensity: Harder efforts burn through carbs faster; choose simpler, faster‑absorbing fuel.
• Terrain: Climbs/technical sections limit eating; stash easy‑grab carbs and small, regular sips.

Step 2. Set your carbohydrate targets per hour

Carbohydrate tops up the limited stores that get you through roughly 60–90 minutes of work. After that, steady hourly intake is the difference between cruising and bonking. A practical range for nutrition for trail runners is evidence‑based: aim for 30–60 g per hour once you’re past 60–90 minutes, 60–90 g per hour for most longer efforts, and about 90 g per hour in races over 2.5 hours. The very front end of ultra runners can push 80–120 g per hour—only with gut training.

• 30–60 g/h: For steady runs beyond 60–90 minutes; start here if you’re new to fuelling.

• 60–90 g/h: For long or harder days; target the higher end as duration and intensity rise.

• 80–120 g/h: Competitive ultras only—build up gradually in training.

• Split the hour: Take 2–4 small feeds every 20–30 minutes.

• Mix formats: Gels, energy drink and easy solids; many use glucose + fructose blends to support higher intakes.

• Don’t force it: If your gut protests, ease back and space feeds—getting close beats overdoing it.

Step 3. Plan your hydration and electrolytes

Hydration keeps your heart rate, pace and focus steady, but more isn’t always better. For shorter runs, water may be enough; once you’re past 60 minutes, include electrolytes to replace what you lose in sweat. Favour isotonic or hypotonic drinks for better absorption, sip little and often, and avoid “chugging” large amounts that your gut can’t handle.

• Pre-hydrate: Drink up to 500 ml 2–3 hours before you start.
• During (little and often): Sip 100–200 ml every 20–30 minutes (~300–600 ml/h) on most days.
• Don’t overdo it: Your body can’t absorb more than about 700–800 ml per hour—going beyond this risks stomach issues.
• Add electrolytes >60 min: Use an electrolyte drink/tablet to replace sweat losses; water alone won’t cover sodium on longer, warmer runs.
• Practical tip: Keep one flask with electrolytes and one with water so you can alternate based on effort and taste.

Step 4. Build your pre-run meals and timing

A good pre‑run meal tops up glycogen, settles the stomach and sets the tone for steady energy. Keep it familiar, carb‑forward and timed so you start feeling light, not stuffed. As a rule used in nutrition for trail runners, go balanced the night before, then simple and lower‑fibre on the morning of your run, with calm, measured hydration.

• Evening before: Aim for a balanced plate (~50% carbs, ~25% protein, ~25% fruit/veg). If you’re prone to gut issues, dial down high‑fibre foods and dairy.
• 2–3 hours pre‑run: Eat a carb‑focused meal you digest well (porridge, peanut‑butter toast or simple cereal). Keep fats and fibre modest. Sip up to 500 ml fluids in this window.
• 30–60 minutes pre‑run (optional): Take a small top‑up if you need it—half a bar, a banana, chews or a gel.
• Early starts: Can’t face solid food? Use a carb drink or an energy bar on the way, then begin your in‑run fuelling early in the first hour.

Step 5. Fuel during the run with gels, drinks and real food

Once you’re moving, hit your hourly carbohydrate target with formats that fit the terrain and your gut. On steep or technical sections, sipping a drink can be easier than chewing; on smoother ground you can rotate gels and simple solids. Longer efforts benefit from steady, regular intake and choosing carbs you’ve practised—don’t experiment on race day. Plan ahead for what’s at aid stations so you can top up confidently without guesswork.

• Gels: Quick to use when breathing hard. If thicker gels bother you, squeeze 1–2 into a soft flask and sip gradually—this can ease digestion over many hours.
• Carb drinks: Isotonic/hypotonic mixes deliver carbs and electrolytes in small sips and work well when eating is awkward. If your drink carries carbs, reduce gels accordingly.
• Real food: Go for easy, lower‑fibre choices in small bites (soft bars, rice cakes, bananas, potatoes, chews). Fresh fruit and complex foods can be harder to digest at higher race paces.
• Cadence: Eat every 20–30 minutes; set reminders and adjust timing so you fuel on runnable sections rather than mid‑scramble.
• Mix formats: Combining gels, drink and simple solids helps many runners reach 60–90 g/h—and closer to ~90 g/h in efforts over ~2.5 hours with training.

Step 6. Use caffeine strategically (if you choose to)

Caffeine can sharpen focus and reduce perceived effort, but it’s optional and should be practised in training. If you use it, take a dose 60–90 minutes before you start, then top up with about 30 mg each hour using caffeinated gels or drinks. Some runners prefer to introduce caffeine later, just before the effort gets tough. If you’re sensitive to caffeine—or have a medical reason to avoid it—skip it or use non‑caffeinated equivalents.

Step 7. Train your gut and practise your plan

Your stomach is coachable. The more you practise fuelling at running intensity, the better you’ll tolerate higher carb and fluid intakes with fewer cramps, stitches or urgent detours. Build dress‑rehearsal runs where you copy race timing, products and terrain. The aim is to edge towards your target without forcing it—getting close consistently beats overdoing it once.

• Start low, build up: Begin at the lower end (30–60 g carbs per hour once past 60–90 minutes) and nudge towards 60–90 g/h for longer efforts as tolerance improves.
• Feed little and often: Take small bites/sips every 20–40 minutes; set watch alerts so you don’t forget on technical sections.
• Drink smart in practice: Sip 100–200 ml every 20–30 minutes and avoid exceeding ~700–800 ml/h to reduce gut slosh.
• Test formats and textures: Rotate gels, carb drinks and simple solids; if gels get heavy, decant 1–2 into a soft flask and sip gradually.
• Rehearse caffeine (optional): Trial 60–90 minutes pre‑run and ~30 mg per hour top‑ups only if you tolerate it.
• Simulate conditions: Practise in heat/cold, at planned pace, and with the foods you’ll find at aid stations—never experiment on race day.
• Keep a fuelling log: Note grams per hour, products, timing and any GI symptoms; adjust one variable at a time until it’s smooth.

Step 8. Troubleshoot common problems on the trail

Even with a solid plan, trail days throw curveballs. Use these quick fixes to steady energy, calm your gut and reset your fuelling without losing momentum.

• Low energy: Ease pace; take a gel or carb drink; resume a 20–30‑minute rhythm.
• Nausea/slosh: Walk; stop chugging; drink 100–200 ml every 20–30 min; use small isotonic sips; cap intake <700–800 ml/h.
• Cramping: Sip electrolytes; add a small carb feed; reduce effort and keep cadence smooth.
• Gut upset: Skip fresh fruit/high‑fibre/dairy; choose practised, simple carbs in small bites.
• Can’t chew/technical: Use gels or a carb drink; decant gels into a soft flask to sip.
• Caffeine jitters: Stop caffeine and switch to non‑caffeinated gels/drinks until settled.

Step 9. Adjust fuelling for heat, cold, altitude and technical terrain

Conditions shape nutrition for trail runners more than you think. Heat ramps up sweat and sodium loss, cold blunts thirst, altitude can suppress appetite, and technical ground steals chances to eat. Keep the core rules—hourly carbs, little‑and‑often sipping, electrolytes—and tweak the delivery so you still hit targets without upsetting your gut.

• Heat: Sip 100–200 ml every 20–30 minutes with electrolytes; cap fluids at ~700–800 ml/h. Shift more carbs to drinks and keep aiming for 60–90 g/h (closer to ~90 g/h in >2.5‑hour efforts).
• Cold: Thirst drops—set timers to drink and use electrolytes on runs >60 minutes. Pack soft, low‑fibre carbs that won’t turn rock‑hard.
• Altitude: Appetite often dips—favour isotonic/hypotonic carb drinks and small, frequent bites to meet your hourly target without GI distress.
• Technical terrain: Fuel on runnable sections; decant gels into a soft flask and keep snacks front‑accessible. Use watch alerts to hold a 20–30‑minute feeding cadence when scrambling or descending.

Step 10. Plan for long days and ultras with aid stations and drop bags

On ultras, aid stations and drop bags are your mobile pantry. Plan stops by time, not distance, so you still hit your hourly targets: 60–90 g carbohydrate (closer to ~90 g/h beyond ~2.5 hours) and small sips of fluid (100–200 ml every 20–30 minutes), keeping total intake under ~700–800 ml/h. Build the plan you practised—nutrition for trail runners rewards routine over improvisation.

• Recon the menu: Check what’s offered and prioritise easy carbs (bananas, boiled potatoes, simple soups). Fresh fruit can be harder to digest at higher race pace—choose what you’ve trained with.
• Pack “hourly bags”: Zip‑locks with 60–90 g of carbs plus electrolytes. Mix formats (gels, soft bars, drink mix) and label by segment/time.
• Bottle strategy: Carry one electrolyte and one water flask; stash pre‑measured drink sachets in drop bags for fast refills.
• Gel flask hack: Decant 2–3 gels into a soft flask and sip steadily between stations to ease digestion over many hours.
• Late‑race options: Include a savoury/simple item for palate fatigue and, if you use it, a caffeinated gel for the tough later segments.
• Checkpoint routine: Keep a 30–60 second checklist—refill, grab the next hour bag, take a small sip/bite, move out walking while you eat, then run.
• If it unravels: Missed feeds or nausea? Walk briefly, switch to isotonic sips and small, frequent bites, and rebuild your 20–30 minute rhythm.

Step 11. Choose foods that suit your diet and tolerance

The best nutrition for trail runners is the food you can actually digest at pace. Build your plan around your preferences (vegan, gluten‑free, lactose‑free) and your gut history, and practise everything. Keep race‑week choices familiar, lower in fibre, and avoid “new” products on the day.

• Go lower fibre pre‑race: Swap wholegrains for white rice, simple breads or rice cakes; many runners also avoid dairy the day before if it bothers them.
• Favour simple carbs on the move: Gels, chews, soft bars, bananas and boiled potatoes are easy options; fresh fruit can be harder to digest at higher race pace.
• Keep it gentle and small: Complex, fatty or fibrous foods are tougher on the gut—use small bites and sips.
• Manage sweetness fatigue: Rotate textures/flavours and consider a savoury option (light soup, salted crisps) later on.
• Caffeine is optional: If you’re sensitive, choose non‑caffeinated versions; only use caffeine you’ve practised.
• Allergies/intolerances: Pack your own trusted items and check what’s at aid stations in advance.

Step 12. Recover right after your run

The run isn’t over at the finish. Recovery starts in the first hour: replace glycogen, repair muscle and rehydrate. Keep it simple—protein plus carbs, sensible fluids, then a balanced meal. Liquids help when appetite is low after hard or hot efforts.

• Protein: Aim for 0.3–0.5 g/kg within 30–60 minutes.
• Carbs + fluids: 400 ml recovery drink now, another 400 ml 1–2 hours later; then eat a balanced meal.
• Hydrate smart: If you’ve sweated heavily, include electrolytes; use liquid calories and sip rather than chug.

Step 13. Carry your fuel smart: bottles, flasks, packs and packing tips

Make fuelling automatic by carrying it where you can grab it without breaking rhythm. Match your carry to the day: handheld or belt for shorter runs; a running vest for long, hilly or changeable conditions. Keep “now” fuel up front, “later” fuel stashed, and balance weight so nothing bounces. Pre‑sort by hour so you hit your carb and fluid targets without thinking.

• Two‑flask setup: Keep one with electrolytes and one with water; sip 100–200 ml every 20–30 minutes and cap total intake at ~700–800 ml/h.
• Handheld/belt for short runs: Minimal carry with space for a few gels/chews and a small soft flask.
• Vest for >2 hours: Use chest pockets for immediate items and rear pockets for spares; adjust straps so bottles don’t rub.
• Label “hour bags”: Zip‑locks containing 60–90 g carbs plus a drink sachet; grab and go at aid points.
• Gel‑flask hack: Decant 2–3 gels into a soft flask to sip steadily on technical ground.
• Mix fast‑fill options: Pack pre‑measured powder sachets for quick refills; wrap flasks in a buff in heat/cold to keep drinks palatable.
• Pack out waste: Carry a small bag for wrappers—clean kit, clean trails, clear head.

Step 14. Sample fuelling plans by run length

Use these templates as a starting point and tweak for your pace, weather and gut. Keep the core rules: steady carbs each hour, small fluid sips every 20–30 minutes, electrolytes on runs over 60 minutes, and never exceed ~700–800 ml of fluid per hour.

• Up to 60 min: No in‑run carbs needed. Sip water to comfort. If starting fasted, consider a small carb top‑up in the final 15 minutes.
• 60–90 min: Aim ~30–40 g total carbs. Example: 1 gel around 40–50 minutes. Sip 100–200 ml every 20–30 minutes; add electrolytes if warm.
• 2–3 hours: Target 60–90 g carbs per hour. Example: 1 bar + 1 gel per hour (≈ just over 60 g) or 2 gels plus some carb drink. Carry one electrolyte flask and one water, sipping 100–200 ml every 20–30 minutes.
• 3–5 hours (mountain long run): Aim 70–90 g/h using a mix of gels, isotonic/hypotonic carb drink and easy solids (banana, soft bar, boiled potatoes). Eat every 20–30 minutes; cap fluids below ~700–800 ml/h.
• 6–10+ hours (ultra): Hold ~80–90 g/h (front‑runners may push higher with gut training). Rotate gels/drink/simple savoury bites; plan aid‑station top‑ups and labelled “hour bags”. Consider caffeine later only if practised; keep electrolytes consistent.

Step 15. Mistakes to avoid with trail nutrition

Tiny errors compound over hours on the trail. The most common pitfalls are easy to dodge if you know them: set clear hourly targets, feed little and often, and keep fluids sensible. Use the checklist below to avoid bonks, gut slosh and mid‑race improvisation.

• No plan: Running without an hourly carb target (30–60 g/h after 60–90 min; up to 60–90 g/h for longer efforts).
• Starting too late: Waiting past 30–45 minutes to take your first carbs; instead, feed every 20–30 minutes.
• Overdrinking: Exceeding ~700–800 ml/h; sip 100–200 ml every 20–30 minutes.
• Skipping electrolytes: Going water‑only on runs >60 minutes or in heat.
• Forcing solids on technical ground: Use gels or isotonic/hypotonic drinks when chewing is awkward.
• Race‑day experiments: New products, flavours or doses you haven’t practised.
• High fibre/dairy pre‑race: If you’re sensitive, keep them low the day before and morning of.
• Caffeine misfires: Big doses without practice; instead, 60–90 min pre‑start then ~30 mg/h if tolerated.
• Not adapting to conditions: Same plan in heat, cold, altitude or highly technical terrain.
• Hard‑to‑reach fuel: Stashing carbs where you can’t grab them quickly—keep “now” fuel up front.

Final thoughts

Trail fuelling isn’t complicated—it’s consistency. Start with the day you’re running, set hourly carb targets, sip fluids and electrolytes little‑and‑often, then practise until it’s second nature. When you do, energy stays even, your head stays clear, your stomach stays calm, and you finish stronger, not just today but week after week.

Now turn the plan into habit. Lay out your flasks, stash your “hour bags”, and make your pack carry the work, not you. If you need simple, reliable kit to make fuelling automatic—soft flasks, bottles, belts or a running vest—explore the range at Take a Hike UK and get your next trail dialled before you lace up.