Fueling Your Training

Lynn Stiff, MD, RD, MS and FCRC Board Member

One of the most overlooked aspects of training is fueling. We wouldn’t expect a car to drive without gas,
a fire to burn without wood or a lamp to light without electricity. But for some reason, we have come to
believe that our bodies are capable of extraordinary feats without the need for adequate energy. Men
and women’s body function differently when it comes to burning fuel and things that have worked well
for some men (i.e. fasted running) are dangerous and counterproductive to women. Regardless of
gender, fuel before, during and after training is helpful. While there are a few famous athletes who have
defied the odds, the fact is they are the exception, not the rule.

One myth that drives this idea is “lighter means faster.” People worry that fueling will cause weight gain
or prevent weight loss and will hinder their success. This couldn’t be more wrong. Runners, even world-
class champion runners, come in all shapes and sizes. Restricting nutrition to become faster just doesn’t
work. You become faster when you have adequate training which needs to be fueled by adequate
nutrition and recovery.

While some people take up running to lose weight, that is not who article this is written for. This is
written for runners who desire to perform to the best of their abilities. Depending on your fitness and
health status when you start running, you may lose weight in your training, but that is not the goal.
Weight loss during training is often a sign of either over training or under fueling, so it is very important
that you set your intention from the start. If it is to reach your top performance, keep reading.
Fueling during training is preparation for race day. It helps train your gut to tolerate nutrition during
intense exercise and helps you determine the best intervals for nutrition and hydration. While you will
likely fuel more aggressively on race day, that is because you are working harder than you will work
during most of your training sessions. The more intense the workout, the more fuel you body will need.
For most of the breakdown you need to know what counts as 15g. of carb. Here is a handy resource.

Fueling starts before you take your first step. Many runners, especially morning runners, run faster. This
is setting your body up for failure. While you can physically run fasted, it will limit your performance of
the run, hinder recovery after the run and can increase your risk of bone stress injuries during your
training cycle. You do not need to consume much before a run and even those with the most sensitive of
stomach can adapt to tolerate pre-run nutrition.

You only need carbohydrates before a run. The easiest option is 4 ounces (1/2 c) of juice. My favorite is
cranberry juice since it is a lighter juice and not overly sweet. If you’re ready to move on to solid foods
pre-run, 1 full graham cracker is close to 15g of carbs and will do the trick. Try to do this 15-30 min
before a run. If you are someone who gets up and runs right away, just do it before you head out the
door and know it won’t kick in until part way into your run. For later in the day runners – you should do
this if it has been more than 2 hours since your last meal.

Take home point: 15g of carbohydrate 15-30 min prior to your run. No fat or protein.

Fueling during your run is similar to race day. You should not plan to do a long run without fuel. While
you can get away with this, your performance will suffer, you’ll likely bonk at the end and your recovery
will likely be inadequate. For ease of understanding, I will break this down to easy running and hard
If you are running easy, you can skip fueling during your run if you keep it so less than 60 minutes. Once
you reach an hour, you should consume 15 grams of carb and then repeat this for every 30-45 minutes,
whatever feels best for you body.
If you are running hard, you should start fueling at 45 minutes and then take 15 grams of carb every 30
minutes thereafter. Some elite runners will take upwards of 90 grams of carb per hour, so experiment
with what works best for you.
If it is time to refuel on your run and you have 10 minutes or less left if your run you can choose to skip
your last fuel as it takes about this much time to really start working. However, taking the fuel could give
you a final kick and will help with your recovery.
Take home point: Start fueling at 45-60 minutes and repeat every 30-45 minutes during your runs. The
harder the run, the earlier and more often you will fuel.

If you’ve fueled well during your run, you may notice it will be easier to get in your post-race nutrition.
This is because your body is not stuck in “fight or flight” (sympathetic nervous system) and instead can
easily move to “rest and digest” (parasympathetic nervous system). Inadequate fueling is a stressor on
our bodies and is actually a double-edged sword – we did not get enough nutrition during the run so we
had to breakdown stores to perform AND now we are too stressed to replenish those stores so we can’t
recovery adequately. Post-run nutrition has 2 phases.

Phase 1: 30-60 minutes post-run: during this phase it is important that we consume a mix of carb and
protein. Ideally 30 grams of carb and 15 grams of protein. This helps our body begin recovery and avoid
flipping out of the rest and digest state. This initial recovery will set the stage for the rest of your
recovery throughout the day, so really try to prioritize it. If you ran hard (similar to race effort) you
should consider doubling this.

Phase 2: 4 hours post-run: Be sure to consume a meal that contains at least 60 grams of carb and 30
grams of protein. The harder you ran, the more you’ll need. Studies have found that consuming
adequate carb and protein in the first 4 hours (even better if it’s the first 2 hours) will result in a higher
metabolism throughout the day and more muscular adaptations.

Take home point: Consume at least 30g of carb and 15g of protein shortly after your run and follow with a nutritious meal that has at least 60g carb and 30g protein.

This can all be a lot to implement all at once, so consider prioritizing one form of fueling at a time. I
would start with pre-run, then post-run and finally during run. This order will set your body up for
success and you will likely find yourself wanting to adapt to the next phase of fueling. Good luck and
please share your fueling success stories with me!

Please note, this article focused on nutrition and not hydration. It is a general rule of thumb that you
should consume 12-16oz of fluid before a run and then every hour during. The kind of fluid and exact
amount will depend on many factors (sweat rate, temperature, composition of sweat), so you should
experiment with this as well during training to find what works best for you.

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