How much water, which snacks, when to eat? How to plan your food and drinking right and prevent the dreaded energy bonk high up on the mountain.
How much do I actually need to eat and drink while hiking? The honest answer as a rule of thumb: for a day hike, 1.5 to 2 litres of fluid plus regular carbohydrate-rich snacks — more in heat and with lots of elevation gain. And the most important principle against the dreaded energy slump is thankfully simple: eat before you're hungry, and drink before thirst grabs you. Because the so-called bonk — that sudden collapse with shaking, dizziness and empty legs — ambushes you almost without warning once your carbohydrate stores run empty. On the mountain this is no comfort issue: exhaustion and cardiovascular problems make up only a smaller share of all hiking accidents, but around 37 % of fatal ones. This DOMISPORTS Academy guide shows you how much you really should drink and eat, why drinking more is not automatically safer, and how not to bonk high up.
Plan on 1.5 to 2 litres for a day hike and drink small amounts regularly rather than a lot rarely. Let thirst guide you: "drink to thirst" is, according to sports medicine, the safest strategy. Best suited are water, unsweetened teas and juice spritzers; soft drinks are too sugary. On hot days and with lots of elevation gain your needs rise noticeably.
On short tours you often need nothing along the way; from around three hours of walking a carbohydrate-rich snack pays off. For long efforts, sports science recommends roughly 30–60 g of carbohydrate per hour, and up to 90 g on very long tours (over 2.5–3 hours). Translated: regular small portions — a banana, wholegrain bread, a bar — rather than one big lunch.
The bonk sets in when the carbohydrate reserves in muscle and liver are depleted — the result is low blood sugar with shaking, dizziness, sweating and mental fog. Prevent it actively: eat at calm intervals before hunger hits. If you feel the first signs, sugar helps fastest — glucose, a juice spritzer or a banana — plus a short break.
Hiking burns more than many think: a 70 kg person uses roughly 390 kcal per hour on flat ground, and over 700 kcal in steep terrain with a heavy pack — and every extra load raises the cost noticeably. That's exactly why one cereal bar isn't enough for a full-day tour: plan your food by duration, elevation gain and pack weight, not by feel.
Food and drink are safety on the mountain: descending low on sugar or dehydrated makes you trip more easily — and exhaustion/cardiovascular issues are behind around 37 % of fatal hiking accidents. Drink to thirst, but don't overdo it: excessive drinking beyond thirst is the main cause of exercise-associated hyponatremia (dangerously low sodium) — electrolytes alone don't prevent it if too much fluid goes in. Warning signs are nausea, headache and confusion. A good rule of thumb: you should not gain weight during the tour.
Portion your carbohydrates into hourly bites: divide bars, bread and fruit into small bags at home, one per walking hour, and eat them by the clock, not by hunger. That way you never slip into low blood sugar in the first place, and you notice immediately if you fall behind your plan. Combine it with a fixed drinking rhythm — a few sips every 20 to 30 minutes — and the bonk has no chance.
As a guideline, 1.5 to 2 litres for a day hike, more in heat and with lots of elevation gain. Drink small amounts regularly and let thirst guide you — "drinking to thirst" is the safest strategy. Water, unsweetened teas and juice spritzers are suitable; soft drinks are too sugary.
Fast carbohydrates work quickest: glucose, a juice spritzer or a banana, plus a short break. The bonk is low blood sugar from empty stores, with shaking, dizziness and weakness. Best of all, don't let it happen — eat regularly, before hunger arrives.
Yes, you can drink too much: excessive drinking beyond thirst is the main cause of exercise-associated hyponatremia, a dangerously low sodium level. Electrolytes can make sense in prolonged heat but don't replace sensible drinking — they won't prevent the problem if you drink too much overall. Drink to thirst.
Better not on the way. Alcohol impairs reaction and balance — you need both on the mountain, especially on the descent. That applies to the seemingly harmless summit beer too. Save the beer for the closing stop after the tour, then you can enjoy it without risk.
Regularly and in small portions. Sip a few mouthfuls every 20 to 30 minutes, before thirst grows large. For food, from around three hours of walking: spread carbohydrates across the tour in small bites rather than one big meal, because regular small amounts keep your stores full and your circulation stable.
Weather Changes & Alpine Dangers