Ultrarunning: The Difficulties of Eating While Running

February 7, 2012

This article is part of Endurance Planet’s ultrarunning article series. If you have questions, comments or feedback about “The Difficulties of Eating While Running”, please leave it below in the comments section…

Training to eat or take in any type of fuel while running is constantly advised for ultras. But the task is more easily said than done. You can’t always dictate how your body is going to feel or react when it’s subjected to the challenges of such a race. More often than not loss of appetite, stomach upsets, and nausea are the obstacles that hinder refueling. One must take in food to have the necessary energy to go the distance. But if you can’t even stand the sight of food, then what is to be done?

Loss of appetite

Having no desire to take in solid food during a race is not an uncommon problem for runners and there’s an underlying physiological reason for this. Because your body is in full physical exertion mode, most of your blood and circulation is focused on your muscles and not on you digestive system. When you see food at an aid station and the sight makes you gag, this is likely your brain warning you that there’s not enough blood to go around for processing what under different circumstances would be palatable. This loss of appetite is also aggravated by the stress your body is already experiencing.

One possible way to mitigate this is to actually slow down or even walk the few minutes before you get to an aid station. This can gradually and temporarily decrease the stress and shift you back to a more normal state and appetite. You don’t really have to force yourself to run and eat at the same time either. In an ultra, particularly the really long ones like 100k’s and 100 milers, there will be intervals where you will walk. You might find it easier to refuel during those times.

Of course such a recommendation has a trade-off in terms of performance times. If your main objective is to be competitive, then slowing down or walking too frequently may not really be an option for you.

Stomach upsets

When you take on too many carbohydrates or use them solely for fuel, your stomach and small intestines can become quite acidic. This will lead to stomach upsets and then to nausea. Experienced ultrarunners have noted that one of the typical causes of this problem is the commercial sports drink that’s only loaded up with simple carbs or sugars. A common ingredient in such products is fructose and this type of sugar is notorious for setting off stomach distress. Not adding enough water in mixable energy drinks high in carbohydrates result in too high a concentration of this nutrient. This can be another cause of acidity.

This is one of the reasons why it’s recommended to balance your fuel intake with some fat and protein. Fats in particular can restore the pH balance in your digestive system and thus allow the nutrient absorption flowing smoothly again.


Do you have questions about eating and running problems, or what you’ve read so far? Do you have any ultrarunning pointers of your own to add? Please leave your feedback, comments and questions below, and we promise we’ll respond.

Comments (2)

  • zebban says:

    When I got into running ultras a few years back I experimented a lot with common sports drinks before I read an ad about Hammer Nutritions Perpetuem and decided to give it a try. Perpetuem has been the perfect solution for me, supplying me with all the energy I need during longer training runs and races, from marathons to 100 milers. I never experience any energy dips and the recovery time is so much shorter. I've used Perpetuem as the sole energy source during 100 milers and 24H races without any problems.
    I'd recommend anyone that runs longer than 2 hours at any time to give Perpetuem a try, you just might find a partner for life.

  • Doug Jones says:

    If acidity in the stomach is part of the problem, can you take anything to counterbalance this? Ive tried a product called Rehydrate that claims to have a higher ph (ie alkaline) and maybe this could help. Anything else you could recommend?

    I use Perpetuem but find that I can't take it beyond the first 90 mins of an ultra, becuase the carbs are mainly maltodextrin, which is a longer chain carb. The simpler carbs are easier to ingest at that point.

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