The last thing you want after starting ANY new diet is to experience something like diarrhea. After all, This is the time when you are expecting to see POSITIVE changes in your body. The discomfort of this side effect can be extremely discouraging. But, before you give up on keto, let me say this. Diarrhea is a VERY common problem on the ketogenic diet. It can take MANY months of trial and error before you start feeling awesome on keto. In the following post, I am going to help you fix ketogenic diet diarrhea once and for all.
When it comes to keto, many side effects (such as diarrhea) may be traced back to the SAME root cause – fluid and electrolyte loss. So, I am going to highlight on this issue first since it is important to address. Fluid consumption is CRITICAL as you enter ketosis. Electrolytes are just as important. Sodium, potassium, and magnesium are the key electrolytes to keep an eye on. When we combine fluid loss with electrolyte loss, this becomes a recipe for MANY different keto side effects. So, we have to make sure we get these two things right first!
There are of course other potential culprits. As we reach ketosis, our bodies will produce new digestive enzymes. These new enzymes will support fat consumption. And, this adaptation takes time. We’ll also begin INCREASING certain fatty foods and REDUCING others to actually adhere to keto (Go bacon!). This can contribute to food sensitivity issues. Another potential cause is the supplements that we consume. There are a number of supplements and fat types that can contribute to diarrhea on the ketogenic diet. Keep reading to find out what these problem-causing foods are.
So, where do we begin?
1. Increase Fluids and Electrolytes
Fluids and electrolytes are extremely important for fighting diarrhea on the Ketogenic Diet. You can lose up to 10 pounds of water weight on keto in the first few months. Electrolytes will also exit the kidneys along with fluids. Sodium is the electrolyte lost the most.
To increase sodium, try adding some bone or chicken broth to your diet. Both bone broth and chicken broth are easy on your stomach.
For potassium and magnesium, increase your intake of green leafy vegetables. Spinach, kale, and broccoli are great sources. I can’t recommend enough how important vegetables are to consume on keto. You’ll not only be getting a healthy amount of electrolytes, but also vitamins, and fiber.
2. Build Up Digestive Enzymes
As your body adjusts to a higher amount of fat being consumed, it will modify its metabolic machinery needed for fat digestion. This includes making changes to your digestive enzymes. Keep in mind – this adaptation DOES NOT happen overnight and your body may be sensitive to certain fats in the meantime. This can contribute to an increased risk of experiencing diarrhea on the ketogenic diet.
Certain fats may cause digestive trouble. Two fats that require special enzymes are MCT oil and coconut oil. If you are just starting out on keto, I would recommend not consuming larger than a teaspoon of these fats at any given time. Also, try your best to consume MCT oil and coconut oil WITH food. That will reduce the chances of it causing diarrhea.
A recent study confirmed this issue happening in children. They used high amounts of MCT fat in children with epilepsy. The researchers found that a number of the kids experienced diarrhea and nausea as a result of the diet. To fix the issue, they temporarily reduced the number of MCT fats they were giving those children. [*]
You can help your digestive enzymes by adding an ox bile supplement prior to a meal. Ox bile is great for aiding in fat break down. This is especially true if you are doing keto without a gallbladder. [*] Some have claimed that Ox Bile also helps in removing a keto rash. This is due to the detox effect that ox bile has with removing toxins released during fat breakdown.
3. Cut Back on Artificial Sweeteners – Sugar Alcohols
Sugar alcohols such as xylitol may cause gastrointestinal disturbances in some people. When mixed with liquids, xylitol is more likely to cause a problem. Consuming xylitol with food is a better option. It is also recommended to stay below 10g per day of xylitol.
Over time, the body may adapt to sugar alcohols. In long-term trials, it has been observed that the gut adapts to higher levels of xylitol. The changes take place in the gut flora and possibly by enzyme induction in the liver. Unlike xylitol, Erythritol does not normally lead to gastrointestinal changes so it is better tolerated. [*]
There are a few sugar alcohols that are known to cause diarrhea on the ketogenic diet (below). This list isn’t exhaustive but, if you are having symptoms, try cutting back on these artificial sweeteners.
Common Sugar Alcohols Known to Cause Problems
4. Identify and Remove Food Sensitivities
It’s also likely that your diarrhea is being caused by a food sensitivity such as lactose intolerance. [*]
I’d like you to try something to help isolate the issue. Take a few minutes and write down all the big foods that you have introduced or INCREASED since starting keto. It’s possible that these foods are causing the problem.
Now, you may want to consider removing foods from this list one at a time until you find the culprit. It is normally FAR easier to fix the issue by simply REMOVING foods than by adding other foods back in. You could be making the issue more complicated for yourself. Reduce the number of variables that you are working to help identify the problem.
If you are still having issues with diarrhea, begin removing the foods below one at a time. Give yourself at least 1–2 weeks between each food removal to make an assessment.
The following foods are known to cause allergic reactions in some people.
Consider the fats that you are eating. When given the choice, your cells will choose to burn mono-saturates and saturates as fuel while in ketosis. 
Good Mono-unsaturated Fats
- Olive Oil
Good Saturated Fats
- Cream Cheese
- Heavy Cream
5. Increase Probiotics
Consider adding some probiotics to your diet to help improve gut microbiome health. These are typically found in fermented food.
Good Natural ProBiotics
- Raw Sauerkraut
- Kim Chi
6. Consume Prebiotics in Moderation
Some prebiotics may actually CAUSE diarrhea on the ketogenic diet if taken in large amounts. This may sound strange but they also have mild laxative properties. If you are already consuming a lot of foods that are high in fiber or oligosaccharides (type of pre-biotic), consider cutting back. While they are very healthy and *do* promote the growth of gut bacteria, they can cause diarrhea when consumed in excess. This is because they typically make their way to the lower parts of the intestine before being consumed by the bacteria that inhabit there. [*]
As you will see below, sugar alcohols actually have some prebiotic properties to them and may help with constipation (But can also cause diarrhea in higher quantities)
Recap – Fixing Diarrhea on the Ketogenic Diet
Yes, diarrhea is a very common side effect on the ketogenic diet. Today we learned that solving it may take a bit of trial and error. But, diarrhea can be fixed relatively quickly if you work through the common causes. Here is a quick recap of what we discussed above.
- Ensure that you are hydrating and consuming enough electrolytes with your increased water loss.
- Allow time for your digestive enzymes to adapt to fat breakdown. Reduce MCT and Coconut oil consumption and consume with food. An ox bile supplement may help fat breakdown.
- Reduce the consumption of sugar alcohols such as xylitol.
- Check for newly added foods. Remove possible food sensitivities one at a time.
- Consume quality fats from mono-unsaturated and saturated sources.
- Add Probiotics to your diet.
- Consume Prebiotics such as oligosaccharides in moderation.
Words of Caution: Keto may not be the cause in your particular scenario. If you have been experiencing diarrhea for an extended period of time, please seek professional medical advice from your physician. This is not normal.
Interested in further reading on the side effects of the ketogenic diet? Check out our post on 18 side effects and solutions on the ketogenic diet. I have not come across a more comprehensive list than this. Surprisingly, many of the most common side effects on keto have the same root cause.