Can Underfueling Cause Bloating?

Bloating is one of the biggest complaints I hear from athletes. Bloating makes many athletes feel uncomfortable and can affect their body image. Both can negatively affect your confidence and performance in your sport!

One way that someone may try to get rid of their bloat is by eating less, but does this solve the problem? Eating less or under-fueling may be the source of your bloat and making it worse; which is what we are examining in today’s blog! This blog post will be answering the common question: can underfueling cause bloating?

What is Underfueling?

Putting under-fueling simply, it is when you are not consuming as much energy as you are burning in a day. This causes an energy imbalance in your body, leading to weight loss and other negative health risks. 

Our bodies burn a certain amount of energy each day, even if we don’t move at all! From there, you can add on burned calories simply by moving around doing your daily activities. When you are an athlete, you add an extra step up in burned calories when it comes to training and games that you may have day to day. 

Many athletes are practicing most days,  sometimes twice a day, and this makes it easy to not be consuming enough calories. There are many ways you can be under-fueling, and you could not even realize it. It’s common for athletes to have decreased hunger due to nerves or choose not to fuel before a lot of movement due to GI distress. There can be many underlying reasons for under-fueling, many of which aren’t even noticeable until issues begin to arise. 

Importance of Fueling in Exercise

What you eat is the energy that is provided when you exercise and train, which leads to your success. You may have heard the importance of pre and post-training fuel, but food is important to be considered throughout the entire day to make sure you are getting enough. 

Food is broken down into three different groups when it is digested in the body, and each of them has an important role in fueling your body for your sport.

Carbohydrates are broken down into glucose, which is used as your body’s primary energy source for high-intensity work (and your brain’s preferred energy source). This is what is included in pre-training snacks as fast-digesting carbohydrates and it is due to the energy that it provides your body to perform at its top level during training. It also can be found in starchy sources such as pasta and they provide energy for longer periods. 

Protein is found in many sources such as animal products, soy, and beans. It is broken down into amino acids which play a role in recovery in our body. Amino acids help build muscles in our bodies and also repair any damage that may occur during training. Protein is important during post-training fueling due to the recovery aspects. 

Fat is found in oils, nuts, seeds, and many other sources. Many athletes may avoid fat due to the bad reputation it has, but it is so vital for you to consume enough regularly. Fat is broken down into a compound called triglycerides in the body and they are used as a concentrated energy source (when we don’t have enough carbs), keeping our bodies warm, absorbing vitamins, and protecting our vital organs. 

Symptoms of Underfueling

Underfueling can show its consequences in many different ways that may not be as obvious as others, but it is important to know all of them so you can see how they could be affecting you. 

Performance-based Consequences

Your performance may be the first thing to decline during periods of underfueling. Here are some symptoms that could be seen in your training:

  • Increased injuries
  • Decreased muscle mass
  • Decreased coordination
  • Decreased improvement in skills
  • Stress fractures
  • Low energy levels

Physical Symptoms

Different symptoms may not be performance-related but can also affect your life in many ways (also not feeling great as a person, often means not performing at the top level!)

  • Absent Period (Amenorrhea)
  • Bloating
  • Decreased bone density
  • Decreased immunity 
  • Feeling cold all the time
  • Impaired growth
  • Fatigue

Mental Symptoms

Underfueling can also interfere with your mental health as it forces your brain to work on lower levels of calories, which can lead to many decreased functions and sometimes disorders. Here are some of the symptoms

  • Increased irritability 
  • Decreased cognitive skills
  • Difficulty concentrating
  • Brain fog

What is Bloating?

Bloating is something that everyone has experienced, and it is normal! Bloating is our body’s natural response to food entering our systems since it takes time to digest, it has to go somewhere. 

Causes of Bloating

Sometimes bloating can be uncomfortable, which can stem from eating too much in one sitting or drinking too many liquids. Some certain foods and drinks may lead to increased bloating, such as gas-producing foods (cabbage, beans, dairy), carbonated beverages, fatty or fried foods, and foods that you may be intolerant to. 

However, just because you are bloated does not mean you should start cutting out foods. Bloating is a natural process that our body undergoes to fit in the food we eat and it will decrease throughout the time of digestion. It is normal for our bodies to look different throughout the day as we eat our different meals. 

Underfueling and Bloating

Can underfueling cause bloating? The short answer is yes, but there are a couple of different reasons why. 

When you constantly are eating less than your body needs, your digestive tract will slow down so that it can save the energy to be dispersed little by little instead of all at once where you may burn through it too quickly. So when you do eat, you may feel full very quickly and feel bloated due to this decreased transit time in your digestive tract. 

When we are underfueling, we may be replacing certain foods with alternatives like sugar-free sweeteners. These sweeteners may be causing bloating and gas due to the chemical makeup of them not being digested in our bodies. 

There is also an increase in gas in our stomach when we underfuel which can also lead to bloating even before we have eaten anything. 


Underfueling can be common in athletes due to the increased needs that may not be as obvious as you think. Your body burns calories just by being alive! So when you add on different factors like daily movement along with training, it is clear that athletes need more calories in a day to match their needs. 

Underfueling can interfere with physical, and mental performance as well as quality of life. Some of the symptoms include depression, stress fractures, and an absence of a normal period. There can also be some symptoms that may be harder to see, such as fatigue, hair loss, increased irritability, and more.

Bloating is your body’s natural response to food entering your digestive tract. It can increase when you consume foods that you are intolerant to, produce gas, or eat too much in one sitting. The feeling of bloating is when you feel too full or feeling uncomfortable after eating. 

So, is there a connection between underfueling and bloating? Yes, there is because when we underfuel, our bodies slow down our digestion to make sure our energy source lasts longer. This is your body’s response mechanism to make sure you have enough energy throughout the day if you are underfueling. Making sure you are fueling properly is important to prevent bloating and other symptoms that can show from not eating enough. 

If you want to learn more about decreasing bloating and solving your GI issues, consider working with a sports dietitian to build out an individualized plan. We offer 1:1 consultations to help kickstart your journey with nutrition education and an individualized plan.

Taking time to optimize your nutrition will decrease your bloating, help you meet body composition goals, and maximize your performance on the field. 
If you are ready to meet your goals, sign up for a 1:1 consultation to get started today!



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