Finding my first 100 miler – Nutrition

Right, this is the bit that fills me with most fear when trying to plan how I am going to get through my first 100 mile event. It seems that nutrition is one of the Ultrarunners biggest challenges. its the single biggest reason why people DNF in 100 mile races. So trying to get this right is important. But its kinda complex, I think. But at the same time it is also pretty simple.

I’ve read quite a bit and a lot of it scoots high above my head and passes by as quickly as I read it but there’s a few things that seem to stick.

These are just my thoughts, what I’m doing to get through to my 100 mile starting line and beyond. I’ve got a lot to do between now and then. A lot of lessons and lot of mistakes to make. I might update this over time as I learn more and gain a bit more understanding of the sort of things I feel work and feel don’t.

Whilst the principles of nutrition are universal (certainly the biology and biochemistry is a given), the solutions are individual and have to be determined, trialled and developed for everyone on their own. What my go to foods are, will equally be no use to another runner.

Calorie Burn

So how much to eat. In a sense of calories i burn roughly 100 calories per mile, give or take. So i can plan my hourly calorific burn based on my intended pace. In an ultra a 9 min/mile pace might well be my target (I’ve not really decided on my 100 mile pace yet) but given this there’s a speed of around 5.5 miles/hour. For me thats about 550 calories an hour.

The general guidance varies a bit from here on in. A reasonable rule of thumb would appear to be that you should aim to recover 30-40 percent of these calories when running at this sort of intensity from carbohydrates. In this example it equates to 165-220 calories and when you convert to carbohydrate thats about 41-55 g of carbohydrate. Thats the hourly consumption when working at this intensity over extended periods of time.

Now maybe that right maybe not. But if you are anything like me, you. want to try and have some basis for determining your consumption over such a long run. And the importance is that when going for that long, getting it wrong can lead to some real gut distress. 70 miles into 100 with your guts fighting against you is not a place I want to be. So anything I can do to try and avoid it is fine with me.

What to eat

For me my routine is chia charge flapjacks and stroopwaffels – both about 250Cals and 20g carbs.

These are items I can eat on the move, comfortably. I often eat these on longer runs and have started trying to consume at a rate equivalent to the above. These just work well and really are easy to get used to eating whilst moving.

Trying new things

One thing I need to try is put some savoury food into the mix. I’ve really enjoyed Jason Koop’s Rice Balls (Bacon and Egg with parmesan cheese rice balls) – google it!

Over the coming months I need to put some savoury food into my longer runs just to see how they sit in the middle of a run. Chicken wraps, noodles. Something for the aid station points.


I like the Kendal mint Cake KMCNRG gels. Refreshing and easily digested. These are about 100 Cals and 20g Carbs. The thing about gels is to not forget to have plenty of fluids with gels.


What works on 20 mile runs won’t necessarily work after 80 miles of a 100 miler. The food I really enjoy after 30 miles in training might be the last thing I want to eat after 65.

It’s important to have some variety. You can plan to consume your favourites throughout the event, but having some backups is key. Being left high and dry with food you cannot stomach and still 40 odd miles of an ultra to go is something to avoid. Im going to follow the idea from the Ultramarathon training book by Jason Koop and set some Bullseye foods. Key foods are at the centre, the ones you rely on most. A mix of off the shelf food (bars/gels) and home made food (like the rice balls). Other foods you go to next in the outer rings of your bullseye and then beyond the target rings are the fall back foods. The ones you keep in reserve in case things go wrong on the reliable food. Of course it is just as important that all these food stuffs are tried on training runs and not just taken along for the ride.


I’e touched on hydration in another post, but there’s an important balance between hydration and nutrition to get right,. If you don’t, your gut simply isn’t going to stay happy, you aren’t going to process food properly and things are going to go bad, quickly. The reason being that to digest food in your small intestine, there needs to be enough fluid. If there isn’t things hang around until the fluid becomes sufficient. If you drink enough, then the fluid will not be far behind. If you are falling short of your hydration needs your gut will try to draw water into the intestine from the body. The problem here is that the body will prioritise thermoregulation over digestion. In other words, your body would rather sweat and lose fluids, than use them to aid digestion. So when you exercise you have to take the fluids needed for digestion onboard manually.

So you can see, that whilst you might be eating the right foods, and the right amounts at the right frequency. But not taking on enough fluid is going to compromise the ability of your body to handle that. That only ends one way …

Getting to the race

So there’s time until my race runs. I’ve got my basis foods and some ideas on the wider food plan. I’ve tried to test out some of my food so far and have a few more to try. I’ll try to have some options for the day when it comes that I believe will work. I’ll try and balance food with hydration. I’ll try to mix things up if some items start losing their interest – after a dozen hours of running nothing would be surprising. But most of all I’ll try to get to the finish line and I will absolutely try to enjoy myself.

3 thoughts on “Finding my first 100 miler – Nutrition

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