Nutritional Needs and ‘Energy Kilometers’

How much Energy do we need on a walking trip? A sensible and healthy diet is vital when physically active. Over and above any normal expenditure of energy under stress, you must also anticipate extra energy requirements caused by certain typical situations such as cold (even when you are resting), altitude, and a drop in atmospheric humidity.

To trek/hike successfully, the body must produce the right kind of energy to fuel the muscles. Without that fuel, the body will slow down, falter and refuse to walk.

Energy is obtained from the foods that we eat. Carbohydrates, fats and proteins which are modified by enzymes in our bodies to produce a form of energy the muscles can use.

Our Three Main Energy Needs:


This is for a short period of time, e.g. dodging a falling rock, regaining balance after a stumble.

Short Term

Energy used for short bursts of intense exercise lasting less than 30 seconds usually, like running away from a fire. This uses stored glucose and glycogen but has lactic acid as a by-product. e.g. the muscles feel like lead.

Long Term

Here the addition of oxygen from breathing promotes efficiency and strength in the cardiovascular system and burns the stores of fat for energy. Fat is very efficient at producing energy and the colder it gets, the more fat is the best choice of energy. In Polar Regions, pure fat is often eaten to produce energy.

Good nutrition is the key to energy. Individual nutritional needs vary, but all of us have a continual need for the essential nutrients supplied by food – for energy, growth, maintenance and the renewal of the body tissue, and for the regulation of vital functions in the body.


Some pointers:

  • Without water we cannot process food. Regardless of altitude we need to take in a minimum of 30 ml or water per Kg of body weight per day to process the food you take in or the energy stored in that food is wasted.
  • At 2000 to 3000 meters (top of the Drakensberg) you must drink at least 3 litres of water a day to make up for losses just due to the altitude. Even when resting you will be consuming about 6000 kilojoules in twenty-four hours.
  • Under stress when trekking, with an oxygen consumption rate that can reach 3 to 4 times the normal rate, consumption can reach as high as 15 000 to 20 000 kilojoules a day.
  • The optimum food ration, however, is only 50% of the Kilojoule requirement; it is advisable to divide it into small, repeated snacks of 1000 – 2000 Kilojoules each, so as not to overload the digestive system. The Kilojoule deficit indicated above is not significant for short periods of up to 4 days as your body has enough reserve to cope with this.
  • The ideal diet contains one gram of protein for every kilo of body weight per day, dividing the rest between 70% Carbohydrates and 30% Fats. However, do not get all your kilojoules from simple carbohydrates such as sweets. Rather get them from complex carbohydrates such as full grain products. (Whole wheat Pasta, Brown rice etc.)
  • The glucose required by the body’s cells is stored by the liver in the form of glycogen, extracted from carbohydrates, fats and proteins (Food). The body normally converts the glycogen to glucose with enzymes and oxygen before using it in the muscles.
  • With exertion, the consumption of oxygen in the tissues increases, but if this is not sufficient, there is a shortage of oxygen and the body starts drawing directly from the glycogen reserves, with the resultant production of lactic acid.
    • This ‘oxygen-less’ reaction releases 16 times fewer kilojoules than those produced in normal aerobic metabolism. In this state the muscles become intoxicated and there is a typical sensation of fatigue. (The heavy burning sensation in the muscles)
  • Lactic acid can only be digested when resting, with an inflow of oxygen through breathing, which turns it into carbon dioxide and water.

Time and Energy is often more important than Distance

You are out on a trek. It’s 9:30 am. The sign at the trail start says there is a great lake just 1.5 kilometres from the camp you are staying at. Easy enough for you and children in the group to do with you and be back at camp for lunch. No need to take food with. Right? It’s only 3 kilometres return. Even at a child’s pace that’s only 2 hours.


What the sign does not tell you is the lake is 300 meters higher than where you are now, and gaining altitude takes energy.

As you gain altitude each 100 meters of ascent uses the same energy as walking between 1.5 to 2 kilometers depending on your walking speed. So that 300 meters ascent will equate to 4.5 to 6 kilometers extra “Energy kilometers”.

Assuming the distance to the lake is 1.5 km each way, that makes it 3 km total, but now we add the energy kilometres needed for the altitude gain which is an additional 4.5 to 6 kilometres. (We only count the up hills)

So now the trip to the lake is going to be a total of between 6 to 9 “Energy Kilometers”. Can you and the children do that before lunch without having substantial drinks and snacks along the way?

A child walking at 1.5 kilometres an hour is now going to take between 4.5 and 6 hours. An adult will take 1.5 to 2.5 hours.

Energy Kilometers Calculator

Energy Kilometers Calculator

In Kilometers
In Meters
Average in Kilometers per Hour
Hours (Excluding Stops)

I have found this method to be a bit more reliable than Naismiths Rule, but like any method you need to personalise or adapt it to your own hiking style.

Your Turn

Give a few examples of trips you know that take longer than anticipated. Do the math. How about Table Mountain in Cape Town? Work out the Energy Kilometers of the popular routes up and add your suggestions to the comments below…

Andrew Friedemann

Author: Andrew Friedemann

Andrew holds qualifications in South Africa, Australia and the UK as an Outdoor Recreation Instructor and qualified Mountain Guide and Instructor. Passionate about developing the Adventure Industry in South Africa to make it safer and provide opportunities to a younger generation of adventurers. Represented South Africa on the World Mountaineering Federations (UIAA) International Training Standards Commission for 10 years and has administered the South African Mountaineering Development & Training Trust. A qualified Wilderness EMT and Emergency Care Practitioner. Qualified as an Skills Development Practitioner, he has been intimately involved in the development of Adventure based qualifications particularly with regard the quality management of adventure qualifications. Founder of Adventure Qualifications Network, he was instrumental in the development of National Vocational qualifications for the adventure industry in South Africa, but also worked closely with Australia where he attained the Cert IV in Outdoor Recreation Instruction. Currently resident in the Scottish Highlands - UK, with his wife, Michelle, they travel to many areas of the world gaining information and skills. A keen adventurer, Andrew has participated in mountaineering, skydiving and scuba diving among other activities.

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