Today’s edition of Dear Mark  is different than most. Instead of doing a roundup of questions, I’m focusing on a single email from a reader who’s hiking around the world in three years and needs a few bits of advice. Of course, this particular reader’s question contains four separate questions, so it’s kind of like a roundup. First is my opinion on the ideal macronutrient ratio – if such a thing exists – for an 18,000 mile hike lasting three years. Second is my opinion on a “fast and feast” cycle for the duration. Third is my take on the place of noodles and rice on a three year hiking trip. Fourth, I offer one final piece of advice.
I depart in summer for a 3 year, 18,000 mile continuous hike around the Earth, via Europe, Asia, Australia and the US. As part of the prep/training I have been paleo for over a year (loving it). Diet and training have been mostly PB standard, and I’ve kept paleo on week long training hikes.
Given the excessive kit I need to carry (up to 50lb) I’ll be chewing through 5000cal daily, and require a sustainable and shop-able diet. Not wanting to down a pint of grease every day, what sort of carbs/protein should I be aiming for? I assumed not more than 300g protein (to avoid ammonia build up and associated thirst) perhaps 200g carbs, leaving over 330g fat (still nearly a pint!)
So, the questions:
1 – Is a 20:30:50 CPF ratio sensible? or would you recommend a different ratio?
2 – What is your opinion on a continuous “fast and feast” cycle (eg 6:1 days) (fast in this case being 2000 to 3000 cal)?
3 – Should/could I include some easy lightweight carbs such as noodles or rice?
4 – Have you any other suggestions in any regard?
Thank you for your time, it is appreciated as is the MDA site.
I had thought that a weekly schedule of 20 miles for 5 days, 30 miles for 1 day, then rest for a day at a food stop for a serious binge. This approach seems logical to me, especially as I usually throw in a Tim Ferriss style binge once every few weeks. I know to expect to take what I can get on the road, and have done training-fasts (0cal + 10km) up to 5 days.
Fortunately, the traditional nomadic diet of the Kazakhs is mostly horse fat and fermented mares’ milk is still prevalent, though some areas I pass, such as northern India, are mostly vegetarian.
I will be using body-centred load pack (Aarn bodypacks) and minimalist boots (Russell moccasins) to keep as natural a gait as possible.
I appreciate that any suggestions/recommendations you give are taken at my risk.
First of all, I’m jealous! What you’re doing is precisely what I’d like to do if I was younger with fewer responsibilities. You’re going to have an incredible, life-altering time and come out a better, changed man for it. Now, for the questions:
20 miles a day with 50 pounds on your body is going to be rough.
Take a look at Table III from this paper (PDF ), which details the respiratory exchange ratio (RER) of subjects doing loaded marches. The RER is a rough approximation of the type of fuel being burned by the body. An RER of 0.7 means almost pure fat-burning, while an RER of 1 and above means almost pure carb-burning. By looking at the RER in response to marching with different loads up different grades, we can get an idea of what type of fuel you’ll be burning on your trip.
RER of people carrying 25.2% of their body weight was 0.87 (0% grade, flat ground), 0.89 (5% grade), 0.94 (10% grade).
RER of people carrying 32.7% of their body weight was 0.9 (0% grade), 0.92 (5% grade), 0.99 (10% grade).
RER of people carrying 38.4% of their body weight was 0.91 (0% grade), 0.91 (5% grade), 0.96 (10% grade).
RER of people carrying nothing at all – so just walking along a flat surface – was 0.85. That’s a roughly even mix of fats and carbs.
Generally, the higher the load and/or the steeper the grade, the higher the RER and the greater the reliance on carbohydrates. This should come as no surprise, as increasing the weight you’re carrying and walking up a steeper grade while doing it increases the work being done and shifts it toward the anaerobic  pathway.
As the heart rate increases, your RER and reliance on carbohydrates will increase, so you can use that as a barometer.
You mentioned carrying 50 pounds, which for a 180 pound human would be about 28% of bodyweight. If you’re about 180 pounds, your RER should be around 0.88 on flat, 0.9 on a slight uphill, and 0.95 on a steeper grade. I imagine most of your hiking will on relatively flat ground, though, which based on an 0.88 RER has you burning  about 60% carbs, 40% fat.
There are a few caveats:
The subjects in these studies were not fat-adapted. If you are fat-adapted  – and being paleo for over a year, you likely are – you’re going to be able to perform the same work at a lower RER, simply because you’ve trained your body to access fat for energy more efficiently. That 0.88 RER I tentatively quoted you above might drop a few points if you’re good at burning fat, so you’ll need fewer carbs.
The studies were short, with some of the marches lasting just 30 minutes. You plan to march 20 miles a day, which will take a lot longer than 30 minutes. Depending on how quickly you complete those 20 miles, you may or may not be going more slowly than the 3.5 miles/hour pace they used in the study. If you go more slowly, your RER will be lower. If you keep up the pace, your RER will be higher. Take that into account when determining optimal macronutrient intake.
I’d say 50/30/20 F/P/C is a good start. I’d recommend swapping protein for carbs, as that’s a pretty hefty load of protein , some of which may be getting broken down into amino acids for energy or converted into glucose. Meat  can get expensive on the road, so you might want to cut out the gluconeogenesis middleman, save some money, and do 30 carb, 20 protein breakdown instead. Don’t be afraid to adjust upwards or downward based on your results and performance.
Be flexible with macronutrients. If you’ve been Primal for awhile, you should be able to shift between fat burning and carb burning with relative ease.
What do you want out of it? Are you trying to lose weight ? That will happen regardless; you’re walking around the world while carrying a heavy pack! Are you trying to stave off some neurodegenerative disease ? The novelty of experiencing a hundred different cultures, languages, cuisines, and climates will be mental stimulation enough, I’d wager.
If a fast “just happens,” so be it. But if you’re putting in 20 mile days consistently with a pack on your back, I’m not sure it’s a good idea. You’ll probably be fine with it, mind you. I just don’t see the point.
I can’t support wheat  noodles as a staple, but rice and noodles made from rice are fairly free of anti-nutrients, aren’t going to kill you, and they may provide a valuable source of easily accessed starch that you find valuable on your journey. Plus, outright resistance to them for paleo reasons might stand in the way of you and a great meal somewhere, or offend someone who’s just being hospitable.
If you’re still wary of rice, check out my post on the subject . Long story short: it’s one of the better grains. Short on micronutrients, but a good pure fuel source.
Remember the 80/20 principle . It was made for those times when you’re offered buuz, a traditional Mongolian steamed mutton (wheat) dumpling, in a new friend’s home, or when you’re enjoying bratwurst in Munich and a tray of mugs filled with a lovely dark doppelbock (and gluten -containing barley) comes around, or when you get the chance to try fried tarantula but you don’t know what kind of oil  they used. I’m not saying you should cheat all the time – and most of the time, you’ll be able to indulge in the local cuisine without going too far off plan – but don’t let pursuit of the perfect  get in the way of your experience.
Above all, have a great trip! Be sure to tell us all about it!