The number of calories you burn on a hike varies more than most people expect. Two hikers walking the same 15km route can finish the day with very different energy costs, and once you understand what actually drives that difference, food planning for a multi-day walk stops being guesswork.
I do not think of this as a weight management question. On a multi-day walk, underestimating your energy needs does not just leave you hungry. It accelerates fatigue and erodes the kind of judgement you rely on once conditions get harder, which tends to happen later in the day when you can least afford it.
Body Weight
Body weight is where the calculation starts, because moving a heavier body over distance means more work for your muscles, your cardiovascular system, and the stabilising structures in your legs and core with every step.
As a general reference, a person weighing around 70kg burns approximately 1,800 kilojoules per hour of moderate hiking. At 90kg, that rises to around 2,300 kilojoules per hour on similar terrain. That gap does not stay small. Over a long day it compounds significantly, which is why a food plan built around a “typical” hiker rarely fits everyone in a group.
Pack Weight
Whatever your body weight, the pack on your back adds directly on top of it. Estimates suggest each additional kilogram of load increases energy use by at least 20 kilojoules per hour, and that figure grows further as terrain difficulty increases.
On a day walk with a light pack this is a minor factor. On a multi-day walk carrying a tent, sleeping system, food, and water, the cumulative effect is substantial. A loaded pack of 18 to 22kg significantly changes how your body responds over a long day, and I notice it most on the descent, when joint load increases sharply and a heavy pack punishes every footfall.
Pack weight also interacts with fatigue rather than staying constant. A load that feels manageable at 8am will feel considerably heavier by early afternoon, which affects pace, foot placement, and decision-making later in the day.
Terrain Type
Body weight and pack weight set the baseline, but terrain is what multiplies it, and it is the factor most hikers underestimate when planning food and timing.
A 5% incline can increase energy expenditure by around 50% compared to flat ground. Steep sustained climbs push that significantly higher. Rough, uneven terrain adds a further 10 to 30% above flat walking, because your body is constantly stabilising against unpredictable surface changes rather than simply moving forward.
Combine a steep gradient with rough ground and you get the highest energy demand of any hiking condition. Australian alpine terrain, rocky ridgelines, and off-track scrub travel all fall into that category, and it is exactly the kind of ground where I have seen hikers most badly underestimate how much food they will need.
Distance and Duration
Total energy expenditure scales with distance and time on the trail, which is straightforward on its own. What is less obvious is how much terrain choice feeds into that total over a long day.
Wolf and Wohlfart’s 2014 study in Landscape and Urban Planning tracked walkers, joggers, and hikers in Australian national parks and compared them to each other on the same trail networks. Hikers consistently burned more energy than the other groups, not because outdoor terrain is inherently harder than a flat, controlled surface, but because hikers tended to choose harder, steeper routes than joggers or walkers using the same network. The real lesson is about terrain choice compounding with time on your feet: the harder the route you pick, the more that difficulty multiplies out over a long day.
Speed and Intensity
Moving faster burns more calories, but not in a straight line. Push your pace much above a comfortable walking speed and the energy cost rises out of proportion to the extra speed gained.
On steep or rough ground, holding a fast pace becomes physically expensive very quickly, which is why a steady, controlled pace on challenging terrain often produces higher total energy expenditure than pushing speed on easier ground. Sustained higher-intensity hiking also elevates your metabolic rate for a period after the walk ends, an effect that can persist for several hours following a hard day on the trail. That is worth accounting for when planning food for the evening and the following morning on a multi-day trip, not just during the walking hours themselves.
Fitness Level
Everything above assumes a given level of conditioning, and fitness changes the equation. A fitter hiker burns fewer calories performing the same task as a less conditioned one, because the body adapts to regular physical demand and becomes more efficient over time.
That matters for planning in both directions. Experienced hikers with a strong aerobic base need to account for their own improved efficiency when estimating food requirements, particularly if they train at higher intensities than they hike at. It also means that maintaining your calorie burn over time requires progressively increasing the challenge of your walks through distance, elevation, or pack weight, because your body will otherwise adapt to whatever you keep repeating.
Fitness also affects how fatigue accumulates across a multi-day walk. A well-conditioned hiker sustains output more consistently and recovers more effectively overnight, which has direct implications for safety and decision-making on longer routes.
Planning Your Energy Intake
Put all of that together and you get a working range rather than a single number. For day walks, most people carry enough food without deliberate planning. For walks beyond one day, it is worth estimating your daily energy expenditure and planning food accordingly.
A rough working figure for a moderate multi-day walk with a loaded pack is 2,500 to 4,000 kilojoules per hour of active hiking, depending on the factors above. A full day covering 20km with 1,200m of elevation gain in warm conditions will sit toward the upper end of that range for most walkers.
Carrying insufficient food on a multi-day walk is not just uncomfortable. It accelerates physical fatigue, reduces cognitive function, and impairs the kind of judgement you need most in remote terrain. I plan food with the same care I plan water and gear, because it deserves it.
For broader preparation guidance see the fitness preparation guide and the first aid kit essentials for multi-day hiking.
