How to Do Intermittent Fasting While Running

What is Intermittent Fasting?

You might have heard about intermittent fasting, but do you actually know what it is? Simply put, it is a type of eating pattern where you cycle between fasting and eating. As a runner, when you hear fasting, you probably think right away that it doesn’t apply to you. You need to get as much food in you for energy! However, intermittent fasting while running has several benefits for all levels of runners when done correctly.

One of the most popular intermittent fasting protocols is the 16/8 method where you don’t eat for 16 hours and only eat during a 8 hour eating window.^[1]healthline – What Is Intermittent Fasting? Explained in Human Terms

Benefits of Intermittent Fasting

Intermittent fasting is not only good for runners, but has many general health benefits. A few of them include:^[2]Everyday Health – 10 Possible Health Benefits of Intermittent Fasting

Boost in Longevity
Increased Brain Function
Less Insulin Resistance
Lower Cholesterol Levels
Lower Risk of Cardiovascular Issues
More Cell Turnover
Protection Against Cancer
Reduction of Blood Pressure
Reduced Inflammation
Weight Loss

Is It Good for Running?

When you run, you expend a lot of energy.

As such, there is a lot of conflicting data and advice whether intermittent fasting is good for runners.

In fact, according to Natalie Allen, R.D., an instructor of biomedical sciences at Missouri State University, “People who work out regularly such as runners need carbohydrates for fuel, as carbs are most easily metabolized into energy by the body…Athletes’ bodies need regular fuel to perform their best. Your blood sugar control, mental clarity (your brain needs glucose), and energy levels can all be negatively affected with intermittent fasting.”^[3]Runner’s World – What’s the Deal With Intermittent Fasting for Weight Loss?

However, it is important to clarify this previous statement.

While racing, it is important to have carbs to help fuel you to the best of your ability.

On the other hand, when training, according to Jason Fung, M.D., author of The Complete Guide to Fasting, “many athletes use ‘training in the fasted state’ to improve performance long-term,” which helps them recover quicker and train harder. Fung elaborates on this saying, “This is due to the physiological hormonal changes of fasting. During fasting, noradrenaline (a neurotransmitter involved in your fight or flight response) and sympathetic tone (where muscle tone is maintained predominantly by impulses from the sympathetic nervous system) increase, allowing for more energy and the ability to train harder. Plus, the amount of human growth hormone is increased so recovery is faster.”^[4]Runner’s World – What’s the Deal With Intermittent Fasting for Weight Loss?

Therefore, when used properly, intermittent fasting while running can be very helpful.

However, before starting any diet and training plan it is important to consult a professional dietitian.

Intermittent Fasting for Runners

So as a runner, how can you effectively implement intermittent fasting into your life?

It all comes down to how your own schedule and amount of time you run.

In general, the 16/8 intermittent fasting plan means that your last meal is around 8 pm and you don’t eat until lunch the next day.

However, many runners like to get their daily training in in the morning before they start their days. Doesn’t this mean that you might finish your run several hours before you even eat? Shouldn’t you be eating something before your run to give you some energy?

According to Michele Fumagalli, LDN, a registered dietitian at the Northwestern Medicine Running Medicine Clinic, it all really depends on how long you plan on running. “If we’re just running for 30 minutes, we’re fine…We have enough carbohydrates stored from our previous meals or the day prior that we can get through a 30- or 45-minute jog.” If you are running longer, you should probably have a small snack to top off your glycogen stores.

She adds that “Maybe you run better if you have some simple carbs before you run, 30 or 45 minutes before. Maybe not…It’s just trying different things out and seeing what might work for you.”^[5]Popsugar – Can You Run While Intermittent Fasting? It’s Complicated — What 1 Dietitian Says to Do

What she says that you should pay more attention to is fueling after your run. If you really want to keep your intermittent fast, you can wait an hour to an hour and a half after your run. In the long run, this could potentially hinder your overall progress as you won’t replenish your body, be hungry, and possibly overeat.

In the long run, even if you are intermittent fasting, a small snack after your run won’t hurt your overall goals.

Some Additional Tips to Make It Easier

Not eating for up to 16 hours while intermittent fasting might seem tortuous. Don’t worry!

There are some tips and tricks that can help you get over the initially break in period to get used to it including:^[6]map my run – Should Runners Be Intermittent Fasting?

Eat 3 Regular Meals a Day

One of the biggest problems that many people have now a days is that they find themselves consistently grazing. That is, they always find themselves with something in their hands to eat.

An easy way to slowly get yourself into intermittent fasting while running is by simply only eating 3 meals a day. Even if you are eating dinner at 7 pm and breakfast at 7 am, this still gives you 12 hours where you are “intermittent” fasting.

Over time, you will get used this this regular schedule and can slowly increase the time between your dinner and your first meal the next day.

Don’t Train Too Hard While Fasted

While fasted training does have its benefits, it is important that you don’t push yourself too hard while intermittent fasting.

In other words, if you are doing long easy runs, it should be fine to continue intermittent fasting. However, if you plan on increasing the intensity of your running with sprints, intervals, or threshold pace make sure to get some food in you.

Front Load Your Calories

Building on the previous point, make sure to take in your calories before the most intense activities of your days. That means if you plan on running in the morning, consider eating heavier breakfasts and lunches and lighter dinners

Don’t Drink Coffee

Don’t drink coffee before going out on your run. In fact, according to Stacy Sims, PhD, and author of ROAR, “As soon as you have coffee, you start to affect the liver, which will release free fatty acids and change a bunch of hormones, which defeats the whole fasting idea.”

Stick with water in order to stay in the intermittent fasting state while running.

Don’t Let Desserts Ruin Your Fast

When you are tired at night, you tend to crave more sweats as you want that quick carb hit. However, this can completely mess up your intermittent fast schedule.

Instead, if you really can’t stay away from the sweets try eating dessert before dinner or even better modifying it to something healthier.

That way you can still satiate your sweets cravings without breaking your intermittent fasting by eating dessert late at night.

Keep Track of Your Nutritional Intake

Building on the previous tip, make sure that you are tracking what you are eating.

If you are getting a sweets craving at night, it is a good indicator that you are probably lacking something in your diet and your body is trying to make up for it.

One of the biggest culprits is that you are actually not getting enough protein!

It is recommended that you should eat around 20 grams of protein per meal with an addition 20 grams after your workouts.

Make Sure You Are Getting Enough Sleep

When you look at the 16/8 plan, you might think that it is nearly impossible to not eat for 16 hours.

However, it is important to realize that you should be sleeping for at least 8 of those hours.

One of the biggest problems though is that most people are not getting enough sleep. Not only is this bad because you aren’t letting your body recover and repair, it also makes it very difficult while intermittent fasting because you are spending more of your waking hours thinking about your next meal!

Final Words

Not only does intermittent fasting have many health benefits, it is also a great part of an overall running plan.

If implemented properly, you can see a lot of benefits in your overall running performance.

If you would like to learn more about intermittent fasting while running and diets for runners in general, make sure to check out the following articles:

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