Why do I Feel Bloated on the Keto Diet? What Causes Keto Bloating

by Sukhsatej Batra, Ph. D August 19, 2020

You have taken a step in the right direction - started on the keto diet and are a week or so into it. But instead of feeling lighter and better, you feel bloated, gassy and uncomfortable! You begin to wonder if the keto diet really is for you? The truth is that you may feel bloated on keto as you are eating unfamiliar or familiar foods in large quantities. Either way, bloating is how your digestive system is responding to the change in your diet, and luckily, it can be fixed. But before starting on correcting this problem, let's start by understanding what bloating is and what causes it on the keto diet.

What Is Keto Bloating?

Bloating can be described as a condition when your stomach feels full, tight, and distended. There is a sensation of continued uneasiness due to trapped intestinal gas and abdominal pressure. In some cases, it may also be visible by an increase in abdominal girth. (1) 

Bloating is not uncommon - as many as 15 to 30% of Americans experience the discomforts of abdominal gas, bloating and distention caused by some of the conditions listed below. (2)

  • Constipation
  • Celiac disease
  • Irritable bowel syndrome
  • lactose intolerance
  • Imbalance of gut microflora
  • Swallowing air

Keti Bloating Causes

A common and annoying side effect you may experience when starting on the keto diet is bloating. This is often referred to as keto bloating because it is triggered by the keto diet. Keto bloating may be accompanied by what you could call the uncomfortable gassy keto effect. On top of this, you may even notice that your pants are getting tighter rather than looser due to abdominal distention. While all these are unwanted results, the best thing is not to panic but realize that this is your body's reaction to the change in diet, particularly if the change is drastic. This change could be from a typical diet that was rich in simple carbohydrates to the keto diet that is low in carbs but high in fat and protein.

Let's go ahead and look at some of the most frequent reasons you feel bloated on a keto diet. 

Low Fiber Intake

While most carbohydrates such as potatoes, rice, bread, pasta, starchy vegetables, and naturally sweet fruits are off the table on a keto diet, there is one type of carbohydrate that should be part of your keto diet. Yes, I am talking about dietary fiber! Let's see why you should make sure you have sufficient amounts of this nutrient when you are on the keto diet.

Dietary fiber is a complex carbohydrate that cannot be digested or absorbed in the human body. It travels intact through the digestive tract - the stomach, small intestine, and colon before being eliminated out of the body. Just because it cannot be digested does not mean that dietary fiber is not an essential nutrient. It is, in fact, a very important nutrient that helps maintain a healthy digestive system by adding bulk to the digested food and aid its movement through the digestive tract. In other words, fiber is essential for making sure that all undigested food is easily and effortlessly excreted from the body. In addition to its role in the digestive system, dietary fiber helps protect against hemorrhoids, colon cancer, obesity, heart disease, diabetes, and stroke. (3)

When starting on a keto diet, it is very easy to decrease intake of dietary fiber as the focus of most meals is on high-fat, moderate protein and low carbohydrate foods.  Eating full fat cheese, steak, bacon, fatty fish, and fried chicken takes precedence over-consuming sufficient amounts of low starch vegetables that provide a good dose of dietary fiber.

In the absence or low intake of dietary fiber in the keto diet, especially when you first start the diet, food takes longer to pass through the digestive tract. The slow movement in the digestive system can result in low carb bloating due to fermentation of the digested food by the gut flora and, if left unchecked, can cause constipation. 

Depending on age and gender, most adults need 21 to 38 grams of fiber per day according to the recommendations provided by the Institute of Medicine (4).  To meet these needs, include nutrient-dense foods that are rich in fiber but low in carbs such as broccoli, cauliflower, spinach, blackberries, raspberries, flaxseeds, chia seeds, almonds, avocado, and asparagus to your keto diet.  You can also add in fiber in a powdered form. In addition to providing fiber that will prevent keto bloating, you will get much needed nutrients and add variety to your diet. As you increase your intake of fiber, make sure to drink enough water as that will help fiber in doing its job.

It is, however, important to note that too much fiber can also cause bloating. A high fiber diet may add too much bulk to the stool, increase its transit time in the digestive tract and result in gas formation in the colon that can also result in bloating and distention. To avoid this, it is important to start by making small changes to your diet at a time and track your fiber intake to find the right amount that prevents you from feeling bloated on the keto diet. 

Limit Intake of Foods High in MCTs

Medium Chain Triglycerides (MCTs) are recommended on the keto diet as they are digested easily by the body and can be used as a quick source of energy. MCTs are valuable in the keto diet as they can help by increasing the rate of ketosis in the body in addition to reducing the amount of food consumed by providing a sense of fullness or satiety.(5)  While coconut oil and palm kernel oils are two main natural sources of MCTs, they contain long chain triglycerides in addition to the medium chain triglycerides. The only sources of 100% MCTs are commercial oils synthetically made from palm kernel or coconut oils. When starting on the keto diet, it is important to check the source of MCTs. Also, many people cannot digest liquid MCT oil. They experience side effects such as bloating, cramping, gassiness, and diarrhea when consumed in large amounts. (6)  If you are experiencing uneasiness, MCT powder may be a better alternative for you. You can find out more about the difference and the benefits of MCT powder in this video.

Keto Foods That Promote Bloating

Now that you can eat all your favorite foods without feeling guilty, you may just be indulging on some that may cause bloating. This can happen even if you do not have a digestive disorder or have never been sensitive to any foods. Some bloating causing culprits are found in common foods such as dairy products and cruciferous vegetables.

Milk and Milk Products

Lactose intolerance is one of the most common causes of bloating, gas and diarrhea. Dairy products contain a carbohydrate called lactose, a simple sugar that requires the enzyme lactase for digestion. Lactase production decreases in many people with age and lactose intolerance is fairly prevalent, affecting about 65% of the world's population.(7)  The good news is that you do not need to go on a completely lactose-free diet if you are lactose intolerant, as most people can digest some amounts of dairy products such as cheese, yogurt and sour cream. Try small portion sizes of dairy products at a time and find the amount that does not lead to bloating.

Cruciferous Vegetables

If vegetables such a broccoli, cauliflower, asparagus, and Brussels sprouts have become your go-to vegetables on a keto diet, they could very well be the cause of bloating. These vegetables contain raffinose, a carbohydrate that cannot be digested but passes intact into the colon where it is fermented by the gut flora, releasing gas and causing bloating. (8) As with other foods, experiment to find amounts you can eat without experiencing discomfort and bloating.


Now that you have a better understanding of why you are feeling bloated on the keto diet, you can start making changes to your diet to resolve the issue. Make a conscious effort to ensure that you are taking a sufficient amount of fiber and water, pay attention not to over-consume MCTs, and adjust your intake of dairy and cruciferous vegetables to portions that do not cause discomfort. As with any change, let your body adjust to your new eating habits. With a little time, these efforts should pay off so and you can experience the benefits of the keto diet in terms of weight loss and feeling healthier.

About the author

Sukhsatej Batra has a Ph. D in Foods and Nutrition with a passion for motivating people to improve their well-being and achieve results through healthy lifestyle changes. Previously, Sukhsatej has worked as a Senior Research and Development Scientist and college professor.


  1. https://www.ncbi.nlm.nih.gov/pubmed/32246999
  2. https://www.ncbi.nlm.nih.gov/pubmed/?term=PMC3264926
  3. https://www.ncbi.nlm.nih.gov/pubmed/?term=24876314
  4. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fiber/art-20043983
  5. https://www.sciencedirect.com/science/article/abs/pii/S0031938417302111
  6. https://med.virginia.edu/ginutrition/wp-content/uploads/sites/199/2014/06/Parrish-February-17.pdf
  7. https://ghr.nlm.nih.gov/condition/lactose-intolerance
  8. http://www.nutrientsreview.com/carbs/soluble-fiber-raffinose-stachyose-verbascose.html
Sukhsatej Batra, Ph. D
Sukhsatej Batra, Ph. D

Sukhsatej Batra has a Ph. D in Foods and Nutrition with a passion for motivating people to improve their well-being and achieve results through healthy lifestyle changes. Previously, Sukhsatej has worked as a Senior Research and Development Scientist and college professor.

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