How much fuel is too much on a long run?

Now that my long runs are creeping up again, and I’m coaching many women training for marathons, fueling is coming up a lot.

What type? How much? How often?

A lot has been written about fueling before, during and after a run.  I’m going to assume you know the basics.

The mistake I see the most often is runners over-fueling the run.

Taking in too many gels can have a negative effect- they teach your body to be dependent on the sugar and this can cause you to feel the “crash” without the sugar “pick-me-up.”

Once you have a little distance under your belt, I’m a big fan of limiting the fuel on a long run.  A little fuel is fine- as it can help you perform better and you definitely want to practice taking in some fuel for race day to teach your stomach how to digest it and ensure that your body won’t reject it.

What kind of fuel? Whatever you prefer… gels if you you don’t mind the texture, chews if you prefer chewing something, or dried fruit if you prefer real food.

With gels, look for lower sugar options.  For example, Clifbar gels have about 13 grams as opposed to Gu that has 28 grams.

How much? You don’t need as much as you might think! Half a pack of HoneyStinger chews is enough to give you a little boost, or a small handful or raisins, or half a gel.

If I decide to use gels in a race, I’ll use them in one or two long runs but sip them over several miles so I don’t get the shot of sugar all at once.

How often? You can begin fueling 30-45 minutes into a long run and continue to fuel about every 40 minutes or so.  If you feel your body crashing before that, you are too dependent on sugar as fuel.

How do you know if you are too dependent on sugar as fuel?

Here are some additional articles I wrote on this topic:

How to determine if you are a sugar burner or a fat burner

How the balance in your every day food choices impacts your efficiency on the run

How I use fasted runs

If you are slightly underfueled, your body learns to adapt and draws more from fat stores than from sugar/carb stores.  Fasted runs will also teach your body to be less dependent on your glyogen stores.

Underfueled or fasted runs makes the run a bit harder… you may not feel as strong as you’d like to, but on race day or runs with the fuel, you’ll notice the difference and be stronger for it.

What’s your go to fuel on the long run?

At what distance do you start taking fuel with you?


I am linking up with SuzRachel, Lora, and Debbie for Running Coaches CornerPatty, Erika, and Marcia for Tuesdays on the Run, Nicole, Annmarie, Michelle, and Jen for Wild Workout Wednesday.

17 thoughts on “How much fuel is too much on a long run?

  1. I use Generation UCAN for my fuel – intense workouts, long runs and races. I’ll have between 1 and 3 scoops before intense workouts and long runs and then I don’t use any fuel during long runs until I get over 18 miles, just water with electrolytes. Of course, I’ve been doing this for several years and my body has adapted to using fat stores. For races, I start fueling around mile 8 or 9.

  2. I agree – I used to take too much in on my runs (and bike rides) and ended up with “gut rot” at Ironman Louisville. My stomach was so off that I couldn’t take in any more fuel, even though I still had 20 miles ahead of me.

    I’ve done a lot to adjust my fueling since then (move toward more fat burning) and am now taking 2 chews every 2 miles on my long training runs. Progress can be made!

  3. Great tips! I underfuel most of my long runs (with a run or two just to test how my stomach handled more fuel) and then take a lot of fuel during my race and it’s like rocket fuel since my muscles are used to less. Sipping my gels makes them so much easier on my stomach, as does using a lower sugar gel (I use Hammer). Training low/racing high fuel and sipping my gels are honestly the two best changes I made to my fueling.

  4. Fueling during has always been my weakest point in running. I do a mixture of fasted and with fuel. I recently started using Tailwind and like it but am not sure if I need a gel in addition to it. I’ve had runs where my stomach is growling like crazy. There’s nothing worse than thinking about food the whole time on a long run. One question I have – if you do most of your runs fasted, how can you be sure that on race day, your body accepts the gel or fuel? I’m afraid my body would revolt on me if I didn’t practice using it during training.
    Angela @ happy fit mama recently posted..Last Week’s Workouts + EnduraPouchMy Profile

  5. I’ve been doing distance running for almost 9 years…and I’m still tweaking my technique. I have had a tough time with the gels in recent years… and I think I was doing the gels fine (one gel every 5-6 miles or so) BUT was adding too much Gatorade (in races) when I really should have just had water instead. I don;’t like the chews…too “chewy” for me
    Kimberly Hatting recently posted..Making the Grade and Back on TrackMy Profile

  6. Great article, as always. Running fuel is a big industry, so no wonder the market is flooded with articles about fueling. I rarely fuel. I will take a gel with me on a 16+ mile run but will only use it if I need it or if it’s super warm out. Like you, I like to do many long runs fasted.

    In a race (1/2 or full), I will overfuel! I have a stomach of iron but I feel like it gives me a psychological and physical boost.

  7. UCAN for me, I don’t fuel unless I am run a half or longer. If I am running 22 or more I use another serving. Ran 50k on UCAN (a drink before and bar during) 300 calories. Works great to burn fat.

  8. This is such an interesting topic and I find it fascinating for what works for some people and not others. Personally, I do more long runs fasted but when I am training for a specific distance event (IE the 2 marathons I ran) I took fuel on runs more than 15.

  9. Great topic for blog post and “fueling” discussion on this topic!! I am so good about hydration and replenishing electrolytes, but still working on something that will help me replace carbs for fueling. I am still new to focusing on and improving my fueling during half marathons. I love Skratch Lab products! I need to go back and thoroughly read all the comments on this post! So helpful and informative!!
    Kara recently posted..Black Bean, Garlic and Butternut Squash Zoodle SoupMy Profile

  10. I really don’t take in fuel on many of my runs. I do eat before my long runs (10+ miles), just something 150-200 calories when I wake up, but I’m not a fan of gels, chews, etc during the run unless it’s a really long run. When I was marathon training, I didn’t get too far into training but I would take one gel on my 16 milers. I’d start with gels on anything 14 or above. I don’t actually run that far in half training, so I’m not using them at all right now.

    I have friends who will run 10 miles and take in two gels for that, and they ate something pre-run! I feel like you have to be conscious of where your fueling information comes from as running stores or companies will definitely advise you on using more than you might really need because they want you to buy. You have to know your own body. I’ve seen people buying gels for 10K races who are convinced they need it for that distance.

    I ran my first half (2011, ran a 2:08) without any fuel during the run because I didn’t know what it was and didn’t want to experiment on race day too much. It’s a tricky thing so if you haven’t done it in training, don’t try it on race day. I also think if you’ve been doing your long runs without it pre-race it’s totally okay to race without out!

  11. Running fuel is a tricky subject because everyone’s physiology is slightly different. Too little fuel and you risk doing damage to your body. Too much fuel and you risk sloshy tummy, sugar dependency and other weird things. I will run anything up to 10-12 miles without fuel but almost always have at least some NUUN for electrolyte balance. That’s the key thing.

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