Below is a further excerpt from my book ‘The Beyond’, a book of tips, ideas and notions based around mountains. All paid subscribers of this Substack will get a special rate on the book.
The hierarchy of human needs starts with oxygen, then water, then food, and is best expressed by the old survival ‘rule of three’, that you can survive for three minutes without air, three days without water, and three weeks without food (this rule isn’t actually true, but it’s a good guide). Although this chapter deals with food and water, and how you cook, heat, or melt it, I think it’s instructive to begin with a deep dive into what it is you’re trying to avoid, that fear almost worse than death: hunger.
If you venture into the mountains, eventually, you’re going to go hungry, sometimes very hungry. Perhaps it’ll be for hours, maybe for weeks, sometimes indefinitely, with no end in sight. Of course, hunger can kill, and for the unlucky adventurer, it will, some succumbing within a day, dying of ‘exhaustion’. In contrast, others, like Chris McCandless, will slowly fade away over weeks, lost somewhere far from anything to eat, the body eating itself instead. Most often, hunger will kill you indirectly, leading to some terminal mistake, choice or bad decision. Just as a lack of sleep creates the same dangers as being drunk, so does an excess of hunger.
Understanding what hunger is, how it affects your mind and body, and how to manage it is a key skill in mountaineering. Your life might depend on it.
Instructive Hunger
For people who have grown up in the West, the awareness of hunger begins small, as a child, only the hint of a tummy rumble, waiting for dinner time, or a reminder to run home and refeed or fill up for more play. If you didn’t grow up with the luxury of dinner or abundance, then you’ll probably have carried hunger around with you like a never-ending headache most of your life, and such people tend to avoid wild places if they can help it.
In terms of mountain hunger, you begin to experience this in your early days on the hills, where bad planning or a lack of experience, or writing cheques your body can’t cash, sees a long day ending without enough food to finish. Such days feel hard, body hollow and empty, your stomach grumbling, your head light-headed, every step like a death march. But such days are almost worth it for the deferred gratification of the payoff, of sitting down with a newfound appreciation of food. I’ve experienced this so many times that I now see that threshold moment, where you reach food, as being sacred and not to be wasted or rushed. I’ve gone for weeks on a starvation diet, but refused the first food I’ve been offered, as it’s not a just reward for going without. Seeing as I’ve waited this long, why not wait another few hours to sit down in a cosy place, with the drink and food I’ve missed the most (I’m a man of simple pleasures, so it’s usually just a cheeseburger, fries and a Coke with ice).
Later, you’ll experience a deeper hunger, sometimes having to operate at a calorie deficit or starvation diet for extended periods, either through a failure in food planning, where even a small calorie shortfall can compound over weeks, leading to a deep hunger, or, circumstance sees you running out of food, leaving you on half rations, and then none.
Yet, all hunger is instructive, and even healthy, if it has an end. Those early hungry days will help you get through future weeks or months, as it teaches how body and mood function with less - or does not pay attention to what your body tells you, yes, it can be painful, horrible, gnawing at you second by second, all you can think about second by second, day and night, but don’t ignore the spiritual aspect. There’s a reason all organised religions pay so much attention to food. You’ll never find wisdom, or any kind of God, with a full belly.
Kilocalorie
First, as biochemical machines, we need some way to measure energy in and out, which we do in kilocalories (kcal), a unit of stored chemical energy, representing the amount needed to raise 1 kilogram of water by 1°C.
An average resting human needs 1 kcal a minute to stay alive, while an active one could burn over 20 kcal a minute. There is a 15% margin based on factors such as age, sex, and muscle mass, which is why a 50kg woman can live on a third less than a 100kg man. However, 1 kcal a minute is easy to visualise.
One kilogram of petrol is a store of 11,500 kcal, fat 9,000 kcal, coal 7,000 kcal, wood 4,500 kcal, and grass 3,000 kcal, but seeing as humans lack a combustion engine or run on steam. Can survive on grass and tree bark, but not well or for long, they prefer the ‘fat of the land’, macronutrients: fat, protein, and carbs, as these can be converted into energy to feed our cells via the digestive system.
Understanding the energy in and out is crucial for sound mountain nutrition, as is its composition (vaseline has more Calories than butter, but you can only live on butter), especially for trips and expeditions longer than a day, where any shortfall compounds over time. You can be 50% short on your ideal Kcal/day on a 24-hour day, but 5% over twelve weeks could feel like slowly dying.
Metabolic Rate
Before determining the energy required for a system, it’s essential to know the energy output, which, in the case of biochemical machines, is measured by our metabolic rate in kilocalories per day (kcal/day). The numbers below are my own and are based on a wide range of scientific opinion. They are a generous average that works for men and women, big and small, and rounded to a number easy to remember in a tent at 6,000 metres.