This is a subject that whole books are written about, blogs are full of, and many, many articles profess to know something about. There are some good sources out there, too. But generally refueling strategies for ultra-endurance events consist of a lot of guesswork and generalizations from other kinds of events. They generally don’t go by the numbers. In fact, I’ve never found one that spelled it on out with math. So let’s give it a shot based on what I know (which is also more than a bit of guesswork.).

Here are some things we know.

• Our bodies can easily burn 500 – 800 calories per hour
• Our bodies can only take in 250 – 300 calories per hour
• An endurance even will have you riding for more than 10 hours a day
• Based on the most optimistic of those numbers(which you won’t get), with all conditions being perfect(which you won’t get), you’ll run a 2,000 Calorie deficit over that riding day.

How do we deal with these facts?

First, you need to get as close to perfect conditions as possible. That 300 cal intake number was super optimistic, and most sources say you’ll get closer to 200. Still, lets try to get your body to absorb 300 calories per hour. The first thing you need to do is make sure your body _always_ has calories available to it. That means you need to eat all the time. But do you eat 300 calories on the hour, 150 calories on the half hour, or something else? Do you eat 600 calories of slower digesting food so your body can digest it at it’s leisure, or do you eat fast digesting food and hope the body will keep it around for the whole hour? These are the questions that need to be answered.

Second, you will not be on the bike all the time. You will stop and rest. Your body needs to be absorbing the maximum calories over this time as well. You need to follow a similar feed strategy as when on the bike to make sure your body always has something to absorb.

Finally, you will sleep. During your sleep, your body still has the ability to absorb calories, but how do you keep that tank full? Do you wake up every hour and eat? Do you pile on a huge, slow-digesting meal so it can keep busy?

Lets talk again about that maximum absorption again. Best case scenario, 300 calories per hour, gives you a max of 7,200 calories per day. A more realistic number, 240 calories per hour, has you only taking it 5,700 cal per day. That’s if you eat perfectly, with fuel available to your body not only every hour you ride, but every hour you’re awake, and every hour you sleep.

Yesterday, on my simple, 100 mile ride on pavement, with less than 8 hours on the bike, my body burned about 6,500 cal. That’s not an ultra distance event, just a good, hard ride on pretty flat pavement. In order to do the tour divide in 21 days, I’ll need to do about 130 miles a day, mostly on gravel, loaded, averaging over 7,000 ft of elevation gain per day. It is crucial to have my body absorbing calories every minute of that time.

For the next installment, more info is needed. Let’s see what we can find.