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The Ketogenic Diet and Its Effect on Digestive Health

Updated: Dec 24, 2023

Let's talk about the Ketogenic diet

The Ketogenic diet is one of the most popular diets these days. It is a low-carbohydrate, high-fat diet that has gained popularity in recent years for its potential health benefits, including weight loss, improved blood sugar control, and increased energy levels. However, as with any dietary change, there can be potential impacts on the digestive system that should be considered.

The problem today is that many people read a lot of incorrect information on the Internet and diet on their own, which ends up being harmful to their health. As a Naturopath who works with patients who face complex health problems, almost every day I meet people who have done one diet or another, so it is important for me to raise awareness of the consequences of such diets on the body and the digestive system in particular.

How does a Ketogenic diet work?

The ketogenic diet was originally designed by Dr. Russell Wilder, at the Mayo Clinic in the USA, almost 100 years ago. A ketogenic diet leads to weight loss by preventing carbohydrates from the body. The body typically uses carbohydrates as its primary source of energy. The total amount of carbohydrates in the Ketogenic diet is between 2% and 4% of the total diet to maintain a carbohydrate intake of 20- 60 grams per day.

So when carbohydrate intake is limited, the body enters a state of ketosis, where it begins to break down fat stores and convert them into ketones for energy. This shift in energy metabolism can have an impact on the digestive system. The main foods are protein and fat mainly from animals, seeds, nuts and some fruits and vegetables. Our digestive system is used to turning carbohydrates into sugar. When the body recognizes that it is not getting its preferred fuel - sugar, it burns proteins instead for several days. But burning protein is not a good idea, because protein is the main substance in our muscles, so burning protein can decrease muscle mass. Our body is very smart and does not allow the burning of protein for a long time. Therefore, it switches to fat burning and this is what encourages weight loss.

When all the reserves of carbohydrates in the body are exhausted, the brain looks for another fuel, because it usually works on carbohydrates. When carbohydrates are avoided and the main nutrition comes from fat and protein, the biochemical mechanisms in our body change, and begin to use fat as fuel, instead of sugar. In order to provide our brain with fuel, the liver turns the fat into ketone bodies - a substance that the brain can burn. When this happens, our body enters a state of "ketosis" (acidosis) - a state in which the heart, muscles, and brain stop burning sugar, and use the ketone bodies as an alternative fuel. A state is created in which the body burns fat and we lose weight In the first days of the ketogenic diet, we also lose a lot of fluid, which increases weight loss. We are also full faster because a high amount of protein reduces the feeling of hunger.

The positive impacts of the Ketogenic diet

Since the main source of fuel in the body is ketone bodies, a variety of positive effects can be seen, such as a reduction in the occurrence of epileptic seizures, slowing down of the aging process, and improvement in fatty liver conditions and joint pain.

Another effect of the diet is the reduction of blood glucose levels and the improvement of insulin resistance. Relatively new studies show that such a diet is good for a variety of conditions, such as diabetes, neurological diseases, acne, polycystic ovaries, cancer, and heart and lung diseases.

The negative impacts of the Ketogenic diet

The Ketogenic diet has an effect on digestive health and it is not always positive.

One potential side effect of the ketogenic diet is constipation. This is because the diet is low in fiber, which is important for maintaining regular bowel movements. To combat this, it is recommended that individuals on the ketogenic diet consume plenty of low-carbohydrate, high-fiber vegetables such as leafy greens, broccoli, and cauliflower.

Another potential impact on the digestive system is an increase in fat digestion issues. Since the diet is high in fat, the body may struggle to break down and absorb all of the fat consumed. This can lead to symptoms such as nausea, bloating, and diarrhea. To mitigate these issues, it is recommended to start the diet gradually and increase fat intake slowly over time.

The ketogenic diet may also impact the gut microbiome, which plays an important role in digestive health. There is some evidence to suggest that the diet may alter the balance of bacteria in the gut, which could have long-term effects on overall health. More research is needed to fully understand this potential impact.

Finally, it is important to note that the ketogenic diet may not be appropriate for everyone, especially those with certain medical conditions. Individuals with pancreatitis, liver disease, or gallbladder issues, for example, may need to avoid or modify the diet to prevent exacerbating their condition.

The effect of Ketogenic diet on Crohn's disease and Ulcerative colitis

Inflammatory Bowel Diseases, Crohn's and Ulcerative colitis, are diseases that occur due to an imbalance of the intestinal bacteria. Currently, there is conflicting evidence regarding the effect of the ketogenic diet on Crohn's and Ulcerative colitis. It is known that this diet starves the harmful bacteria in the intestine because it does not contain sugars and carbohydrates and is low in Fodmaps (short-chain carbohydrates - fructose, fructan, galactan, lactose, raffinose and sorbitol), hence it has the potential to help improve the symptoms of Crohn's and Ulcerative colitis, as well as IBS. On the other hand, a low-fiber diet for a long period of time reduces the diversity of intestinal bacteria, which impairs the health of the digestive system in the long run. A 2021 study published in the Journal of Clinical Gastroenterology, showed that participants who ate a ketogenic diet for 12 weeks experienced relief in their symptoms as well as a positive change in their gut bacteria. In contrast, another study conducted in laboratory mice that same year, and published in the journal Food and Function, showed that a ketogenic diet actually worsens colitis symptoms, reduces the variety of good bacteria and damages the intestinal protective barrier. So as you can see, there is no unequivocal answer regarding the ability of the ketogenic diet to help treat Crohn's disease and Ulcerative colitis. Apparently, for some people this diet can be suitable temporarily, and relieve the symptoms of the inflammation, but due to a significant limitation in dietary fiber, I would not recommend it as a lifestyle for people with Crohn's and Ulcerative colitis, certainly not for extended periods of time.

In conclusion

Like any diet, the Ketogenic diet also has advantages and disadvantages and requires close and strict monitoring of every food consumed. It is important to be aware of its possible consequences on the body (burning of muscle mass, ketosis...). It can also have potential impacts on the digestive system, including constipation, fat digestion issues, and changes to the gut microbiome.

It is important to approach the diet gradually and with caution and to consult with a healthcare provider before making any major dietary changes. With proper planning and monitoring, the ketogenic diet can be a safe and effective way to improve overall health and well-being.

If you are planning to do some kind of diet, I strongly recommend that you thoroughly check all the implications, research the rationale behind it and be aware of the possible health consequences that may arise as a result. Do not go on any diet without fully understanding what it actually does to your body.


1. Masood W, Annamaraju P, Uppaluri KR. Ketogenic Diet. 2. Batch JT, Lamsal SP, Adkins M, Sultan S, Ramirez MN. Advantages and Disadvantages of the Ketogenic Diet: A Review Article. Cureus. 2020 Aug 10;12(8):e9639. 3. Ludwig DS. The Ketogenic Diet: Evidence for Optimism but High-Quality Research Needed. J Nutr. 2020 Jun 1;150(6):1354-1359. 4. Zhou C, Wang M, Liang J, He G, Chen N. Ketogenic Diet Benefits to Weight Loss, Glycemic Control, and Lipid Profiles in Overweight Patients with Type 2 Diabetes Mellitus: A Meta-Analysis of Randomized Controlled Trails. Int J Environ Res Public Health. 2022 Aug 22;19(16):10429. 5. Zhu H, Bi D, Zhang Y, Kong C, Du J, Wu X, Wei Q, Qin H. Ketogenic diet for human diseases: the underlying mechanisms and potential for clinical implementations. Signal Transduct Target Ther. 2022 Jan 17;7(1):11. 6. Kong, C., Yan, X., Liu, Y. et al. Ketogenic diet alleviates colitis by reduction of colonic group 3 innate lymphoid cells through altering gut microbiome. Sig Transduct Target Ther6, 154 (2021). 7. Shengjie et al, Ketogenic diet aggravates colitis, impairs intestinal barrier and alters gut microbiota and metabolism in DSS-induced miceFood Funct., 2021,12, 10210-10225


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