Nutrition when Running Trail Ultra

Hi All,

I am have difficulty in gauging food/calorie / protein intake for a 52km trail run I am doing in two weeks. The road ultras I have completed I did not find keeping fuelled difficult.

But with training in more hilly conditions I have found a dip in energy after 4 hours. I would try to be as full as possible prior to my long runs. Any one any advice on high energy foods I could try as I am using gels and they are not working too well.




  • There is a discussion on as thread at the moment on food people like at checkpoints on ultras... I think it varies  a great deal and us different if youbareca racing snake or more of a plodding tortoise...

    Some use gels but most use some real foods...from cereal bars, energy bars,nuts , dates etc..,through to sandwiches, pasties, crisps and cake.

    Like most things its best to try these things on your long runs to see what you stomach can handle and what works best...

  • You can only absorb around 200 cal an hour but you will be burning 700 or more. So muscle glycogen and other glycogen storage will be depleted and its a case of eking it out and taking in what can be absorbed in a way that is appealing and doesn't give you GI problems. Some people can cope with gels (though fructose will tend give give problems). Others like carbs like cold roast potatoes. Maybe you are going out a bit fast and burning through the glycogen stores a bit quick?

  • GeeeMGeeeM ✭✭✭

    As I understand it, (it's a bit more complex than this - but as a layman's guide)

    You hold about 2,000 calories worth of glucose/glycogen in the liver/blood which is readily available, once you've burnt through that the body must switch to burning fat instead, (ketosis)

    Because "most" people eat a carbohydrate rich diet their bodies aren't used to burning fat for fuel hence they crash, hit the wall, bonk etc... This also explains why marathon runners hit the wall at about 20 miles, (100 calories/mile *20 miles = 2000 calories)

    As Steve said - you can only absorb 200-300 calories / hour, (I work well on about 300/hour) but you're probably burning double that! So, at some point you're going to be in deficit and your body is going to have to start using the fat stores.

    The trick is to eat little and often, 100 cals every 20-30 minutes works well for me. That's a gel, or a couple of fig rolls, half a pork pie, a slice of bread, handful of nuts etc... If you get behind on a longer run it's difficult to come back once you're in deficit. Set your watch on a recurring timer every 20/30 minutes to remind you!

    A few years ago at Thunder Run 24 I tried to eat 600 calories an hour - it was a disaster after about 4 hours! Since then I've used the above strategy and it's worked for everything I've done!

  • Good summary GreenM and others. It fits well with my experience after 100+ ultras. If you look at how much you burn then you are asking for trouble. Look instead on what gives a well-behaved stomach.

    An additional complication if you do not often run really long training runs is that your body gets used only to run out of carbohydrates and do not react in panic to that. It just gears up the fat burning. But after many hours it realizes that this means that fat disappears, and this is a situation that not all ultrarunners give time to train the body for.

    Fat disappearing is not critical since you have a lot of that stored, but the body can activate a self-defense in panic if it is not used to the situation. The body can do this by suddenly pointing out that it wants to restore the fat (and protein) depots and refuses to deal with carbohydrates. The taste buds get involved in this self-defense and for sweat-tasting things they can force the swallow-reflex to refuse to swallow. Basically the body starts a carbohydrate strike in order to clearly point out that it wants something else. Some ultrarunners have understanding bodies and do not get to this stage, while others get this problem even if they are experienced ultrarunners.

    The only way to counteract this that I've found is to reduce the intake of rapid carbohydrates, and especially sweet-tasting, and instead increase the intake of real food and sometimes also more spicy food. A slice of pizza is a favorite of mine at this stage, as well as McDonald's Chicken wrap. Tastes wonderful even when I’ve come to the stage that I cannot even force me to swallow sports drink (almost all sports drinks are sweet-tasting). This means I temporarily exceed 300 kcal/h, but it seems to work if I directly fall back to 300 kcal/h or below.

  • Hi all,

    Thanks for the information. Ill keep it all in mind when doing  my race prep.


  • Some great explanation on here.

    Link below isn't directly relevant to in-run nutrition, but may help explain the protein requirement day-in-day-out whilst training. Less than many people might think. I can easily overdo the 76-90g I need daily.

Sign In or Register to comment.