Last updated on November 30th, 2022 at 04:21 pm
Timing your run around food consumption (and impending bowel movements) can be difficult. To overcome these challenges, you might be thinking about running without eating beforehand. In this post, we explore the benefits and potential problems of running on an empty stomach.
Running on an empty stomach can prevent irritable bowel, contribute to weight loss, and provide aerobic benefits. However, you should eat something before running over 20 miles to avoid hitting an “energy ceiling”.
Why Someone Might Want to Run on an Empty Stomach?
For those of you who have never considered it, it is not total madness. Let me argue the case for the benefits as someone who has experienced them.
Many people arrive at the concept in the exact same way through impatience or a time crunch.
Let’s say you like morning runs but you have other places to be. Eating breakfast afterward means you don’t have to wait at least an hour for food to digest before you can go.
Similarly, preparing and eating dinner after work but before running means you may be out much later than you’d like.
For others, the reasons may be more physiological. I, for one, often get side stitches and other stomach discomforts even after waiting an hour after a meal. And, not eating before I head out for a jaunt almost always circumvents these issues.
Allow me to take you through a host of other benefits associated with this concept.
Benefits of Running on an Empty Stomach
While running before eating can be difficult for some, there are some proven benefits.
Those benefits include:
- reduces instances of runners’ trots
- reduces cramping
- contributes to weight loss
- aids in muscle definition
- contributes to a better level of aerobic fitness
- makes you feel lighter
Reduces Instances of Bowel Movements
As I politely referenced before, stomach discomfort can get pretty serious.
Running can cause a phenomenon known as runner’s trots.
Put simply, this is often diarrhea or stomach cramps caused by:
- The jostling around of food in your belly
- Intestinal hormone secretion that increases the speed of food processing in your body.
Either way, it is entirely avoidable when you do not eat before you are heading for a run.
If you are interested in avoiding runners’ trots, and you should be, definitely check out our post dedicated specifically to Tips for Avoiding Runners’ Trots.
Can Contribute to Weight Loss and Muscle Definition
Exercise and weight loss typically go hand in hand. Unfortunately, the debate about whether weight loss is greater when eating after exercise is not officially settled. However, compelling evidence does exist.
A study published in The Journal of Clinical Endocrinology & Metabolism found that exercising before food may burn as much as twice the fat than having eaten.
Everyone can agree that your body uses food as fuel during everyday living. However, the fuel source most people use comes from glucose stores.
When you have not eaten, your body has reduced glucose stores and will often switch to using fatty acids for fuel.
Although you are burning the same amount of calories, one way is burning fat stores and the other is not.
Burning fat stores leads to lower body fat and better muscle definition if you keep your overall caloric intake reasonable.
May Provide Some Aerobic Benefits
In addition, many runners claim to experience aerobic improvements when they haven’t eaten before exercising.
While this area certainly requires further research there have been some findings.
For instance, a small 2010 study in the Journal of Science and Medicine in Sport argued that running without having eaten correlated to a higher level of fitness and performance.
This happens as your body improves its oxygen efficiency and your VO2 max.
You Feel Lighter During The Run
Finally, it is no secret that it takes at least one hour to digest the food you have eaten. Plus, meals often take 2-5 days to travel through the small intestines to the colon.
For me the time varies depending on the food which makes sense as different foods take longer to digest. For example, high protein or fatty foods take a longer time to go through your system than high fiber foods.
I feel much lighter not eating before a run. And this helps me with form and speed.
Especially when I don’t have these foods jostling around in my belly while I’m demanding more from my body.
Potential Issues Running Without Food
Running on an empty stomach may alleviate cramping or other digestive problems but there are certainly some disadvantages.
Here are the downsides:
- You may potentially hit an energy ceiling
- Increased levels of cortisol may steal energy from muscle mass
- May lead to overeating afterward
- Can exacerbate acid reflux during and after runs
You Might Experience an Energy Ceiling
The vast majority of people who have ever run a marathon experience hitting the infamous “wall” around the 20-mile mark.
Without getting too technical, this is a result of the body running out of glycogen stocks. And you can only store up to 2000 calories of carbohydrates as shown in many studies.
RELATED: 7 Ways to Stop Trots in Their Tracks
Your body is always burning calories even while you sleep.
Without replenishing your glycogen levels, you may limit how much exercise you can do based on the available fuel.
Your body does naturally switch to burning fatty acids but this acts differently as an energy source.
Where many runners hit the wall having dieted effectively, people who haven’t eaten will often experience the demotivation much sooner.
Your Muscles Could Develop Less Efficiently
As previously mentioned, exercising without food can improve muscle definition through fat loss. And, exercise in general typically offers similar benefits in muscle building and definition.
However, these benefits can negatively affect muscle mass in the long term. Especially if your preference is to run in the morning before breakfast. This is due to your hormone, Cortisol produced in your adrenal glands.
When Cortisol spikes, it begins to use protein as a fuel source which it takes from your muscular cells.
As Cortisol is at its highest in the morning and exercise after fasting increases your levels, it is suspected that muscles can become depleted by consistent fasted morning running.
Might Cause Overeating After The Run
The most obvious trade off of foregoing food before running is hunger. I, for one, am not wonderful company when I’m hungry. Regardless, after a hungry run, you may also find yourself eating voraciously for a number of reasons.
For instance, runners understand the need for a healthy diet and post-workout requirements for protein and other nutrients.
And, many runners who carefully plan a meal for after a run can over-estimate the levels of nutrients required because of hunger.
Similarly, you may feel so hungry after a run that you gorge on snacks rather than being selective and intentional about your eating.
Is Running on an Empty Stomach Better?
If you experience chronic digestive issues, regardless of distance it might be an idea to give this a shot. Holding off on eating may suit you.
Similarly, if your intention is to burn fat, there are many benefits to reducing the use of glycogen stores in favor of fat deposits.
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Also, a fun fact is that the 100-mile world record holder, Zach Bitter, formed his diet around eating mostly fats. He did this because they can last longer and burn more efficiently.
Ultra-marathoners aside, these benefits do not apply to everyone.
On longer runs or those with intense challenges, not eating may backfire. In fact, it is often a drain on morale and energy to exercise without food.
As a result, you might find yourself ‘hitting the wall’ much sooner without refueling.
It is not simply a question of one being better than the other, but more of a case by case testing question.
It Isn't for Everyone - And Isn't For All Runs
There are undoubtedly benefits to running on an empty stomach such as fat burning, reduced stomach cramps, and reduced risk of trots. However, as previously mentioned, some potential downsides to running on an empty stomach will leave you wishing you ate.
For example, motivation dips, reduced intense training capability, depleted muscle mass, overeating, and sometimes dehydration can occur.
My recommendation is if you plan to run without food, test yourself on shorter distances and assess how your body feels and reacts.
However, you shouldn’t withhold food on every single run. But, not eating may suit those morning runs when you don’t have lots of time.
Image Credit: Robin McConnell | (source) | Attribution 2.0 Generic (CC BY 2.0) –reduced file size and image
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