How much grub do you need to munch per day on a 3 day hike?

How much grub do you need to munch per day on a 3 day hike?


17 June 2010

Because I'm thick, I'm going to let somebody much cleverer than me do the sums. The massively clever T.M. Carpenter wrote a book called 'Factors and Formulas for Computing Respiratory Exchange and Biological transformations of Energy' ...it hurts my frontal lobe just thinking about the title never mind reading it. In the learned tome, he lists the calorific expenditure of almost every activity.

Here's the figures for hiking:
A 16 stone bloke hiking for 18 miles and slogging up 3000 feet of elevation burns 6500 caloriesA 16 stone bloke hiking for 18 miles and slogging up 3000 feet of elevation burns 6500 calories
Now, that's a lot of Kendal Mint Cake to eat every day. The value is obviously an estimate and your calorific intake will undoubtedly be different from this depending on your weight, speed, temperature, metabolic rate - all sorts of stuff. But it's a start.

How much food does this equate to?
For this, you need to check the food labels. If you plan to eat 6500 calories and the label on the grub packet says you are eating 350 cals/100g (100 cals/oz), the 16 stone man would require a massive 1.8kg (4lbs) of nosh per day. That's (I hate using this computer calculator) 5.4kg (12lbs) in 3 days.

That is heavy, and that is why we need to talk about calorific density. No scholarly document, such as this, should be without an equation, so here's one:

Calorific Density = calories per volume or weight

For example:

Calorific density of Heinz Beans = 72 cals/100g

To survive on tinned beans alone the 16 stone man would have to eat 21 tins of beans per day. That would require a Tesco's van in support and really REALLY good ventilation in your single skinned tent.
To reduce this weight you need to use food that has a higher calorific density
Obvious examples of food with a high calorific density are:

Butter is 700cals/100g (200cals/oz)
Olive Oil is 900cals/100g (250cals/oz)
Cashew Nuts is 560cals/100g (160cals/oz)

Calories of other food...

According to BackpackingLight.com the generally accepted standard for ultralighters is eat food with an average calorific density of 440cals/100g (125cals/oz).
So if you need something to munch while hiking you could have a mixture of the following:
Raisins 290cals/100g (82cals/oz)
Jacobs Tuc Crackers 521cals/100g (147cals/oz)
Cashew Nuts 560cals/100g (160cals/oz)

Resulting mixture is 457cals/100g (129cals/oz) which is above the 440cals/100g average.

Things in my cupboard that have a calorific density greater than the magical 440 are:

Blue Dragon 3 minute noodles 474cals/100g
My daughter's Hula Hoops 514cals/100g
Sunflower seeds 596cals/100g
Packet of Smarties 460cals/100g
(have now been transferred from cupboard to stomach)
Kellogg's Crunchy Nut clusters 435cals/100g
(just below 440 I know but I'm struggling to find anything above)

Pasta and rice both have 350cals/100g and packets of dried veg are similar so in order to boost this to the magic number you will need to add some super dense items like butter or olive oil or pepperoni or nuts.
Calorie breakdown throughout the day
If you're going to be walking lots the best way to spread your calorific intake (according to Ryan Jordan's Lightweight Backpacking and Camping Book) is as follows:

Breakfast 20-25% of daily calories
While walking 50-60% of daily calories in the form of snacks
Evening Meal 20-25% of daily calories in camp meal


So if you did need to consume 6500 calories that would breakdown to:
Breakfast 1600 calories
Walking 3250 calories (say 5 snacks at 650 cals each)
Evening meal 1600 calories

Bear in mind that if you are not 16 stone, or you are not hiking up 3000ft of mountainside per day or you are walking at a reasonably slow pace then you will not need this amount of food
So, how much grub does a 16 stone man need to munch per day while walking 18 miles up 3000ft of elevation?
I will show my workings so I get some marks even if the answer is wrong…

Calories per day = 6500
Average Calorific Density = 500cals/100g
Weight of 1 calorie = 100/500 = 0.2g
Weight of 6500 calories = 0.2 X 6500 = 1.3kg (2.8lbs) per day

Total weight for 3 days = 3.9kg (8.4lbs)

This is still a considerable weight. I think the 16 stone man could take considerably less than this for a 3 day hike and call upon any fat reserves to help him out.
Ryan Jordan's Calorie Intake
BackpackingLight.com's Ryan Jordan takes on average 570g (1.25lbs) of food per day, which is less than half that of the 16 stone man, how comes that??

Last time I went hiking with Ryan across the Arctic tundra…. okay the only people I going hiking with are me mates Baz, Martin and Pete. Anyway Ryan is obviously substantially lighter than 16 stones and will no doubt hike efficiently and conserve energy loss from cold etc

If Ryan also eats food with an average calorific density of 500cals/100g then for 570g of food per day he is consuming 2850 calories per day.

Ryan is a seasoned long distance hiker, weighing maybe 10 stones; the 16 stone man might not be a seasoned hiker (we can decide since we've made him up).
The definitive answer
Chris Townsend in The Backpacker's Handbook reckons men need 360 calories per hour and women need 240 calories per hour while hiking. He calculates that, for a 7 hour hiking day, men would need 4500 to 5250 calories, and women 3330 to 4320 calories.

The calorie range seems to be between 2850 and 6500. I know you were probably wanting a more accurate figure than this, sorry. You probably think I'm going to end with something wishy-washy like 'but everyone's different' or 'the only way to really know is to give it try' but I'm not. I'm going to be very accurate just like those clever Radio 4 people…

that is, if you're a 16 stone man hiking for 18 miles up 3000 feet of elevation. The answer is 6500, T.M. Carpenter says so, and I believe him.

Thanks for reading.

Ian Young
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