Carbohydrates are a rich source of dietary fiber, which adds volume to stools and softens them to make them easier to eliminate. Eating less fiber will have the opposite effect. However, according to the Mayo Clinic, diarrhea is also a common side effect of low-carb diets. The main reason for ketogenic diarrhea is the diet's incredibly high fat content.
Fat takes longer to break down in the body than carbohydrates or proteins. Bile is the product that the body produces to break down fat. It is also a lubricant for the colon. Therefore, your body may be pushing waste through the digestive tract faster than ever before, which can cause diarrhea.
As your body adjusts to this new fuel source, fat, diarrhea is likely to subside after a week or two. When you're on a ketogenic diet, digestive changes often occur. Sometimes these changes are positive, but sometimes you end up with ketogenic diarrhea or ketogenic constipation. Now, keep in mind that the standard American diet gets a lot of its fiber from grains and that the ketogenic diet is low in carbohydrates.
Sugar-free, low-carb products often contain sugar alcohols to give them a sweet taste and avoid table sugar (sucrose). For example, for an obese person who has an unhealthy diet and has been advised to start losing weight quickly, a short cycle of ketogenic diet under doctor supervision may be appropriate, Albenberg says. Based on a typical list of ketogenic diet foods, this approach is high in fat (70 to 80 percent), moderate in protein, and very low in carbohydrates that many people consume 20 to 50 grams (g) per day. Since the standard American diet is high in carbohydrates, switching to a ketogenic diet places you on the opposite end of the spectrum.
If you're experiencing bile malabsorption or want to prevent it in the first place, then you might consider trying the carnivore adjacent diet or the cyclic ketogenic diet. Many people on a ketogenic diet count so-called net carbs, which are grams of total carbohydrates minus grams of fiber. They are usually used to reduce carbohydrates from sugar, but they can do more than just reduce carbohydrate intake.