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THE KETOGENIC DIET AND YOUR MICROBIOME

Updated: Mar 25, 2023

The Ketogenic diet is an extremely popular diet amongst the weight loss community. Originally brought to light for its promising research in epilepsy management, it quickly became a hopeful solution for those looking to quickly shed pounds without massive caloric restrictions. But like any trend, we must weigh all the pros and cons, while simultaneously accounting for the long-term impacts on our health.

First off, let's break down what the ketogenic diet actually involves. The premise of the diet focuses

on reducing carbohydrates to force the body into an anabolic (breakdown) state, known as ketogenesis. Ketogenesis is a metabolic process our bodies enter into when sources of glucose (both dietary and stored) cannot keep us with metabolic needs, forcing the body to produce ketone bodies from adipose tissue (aka fat) to use for energy in place of sugar. As you can imagine, this is favourable for weight loss for several reasons. In addition to fat now being used as fuel, the blood sugar staying so low sharply drops insulin secretion, which further reduces the stimulus for fat and sugar storage. As long as the body remains deprived of carbohydrates, ketosis is sustained and weight loss continues. There’s also the concept of something called ‘super fuel’, meaning ketone bodies produce more usable ATP molecules (aka energy) to the heart, muscles, and brain than glucose, resulting in the additional energy and mental focus many people report while in ketosis.1 Studies are showing very promising results for epilepsy, and have been well documented and proven to be effective for rapid weight loss, with initial weight loss of up to 10 lbs in 2 weeks or less.1 However, literature exceeding 2 years of use is lacking, and some studies raise show some red flags are raised within 3 months into ketosis that may have more concerning health implications long-term. Let’s dive further into what those risks are. #1: Vitamin and mineral deficiencies. While the ketogenic diet does help to eliminate certain unhealthy foods, like refined sugars and carbohydrates, it also eliminates fruits and other vegetables that contain carbs. It’s no surprise that fruits and vegetables provide a primary source of the vitamins and minerals the body needs for optimal health, in addition to being high in antioxidants. Now, there are also two ways to approach ketosis – one that maintains a high low-carb vegetable intake and a balanced amount of saturated fats, and one that involves eating bacon and hamburger patties at every meal. All that aside, Harvard health highlights the most common nutrients depleted on a ketogenic diet are electrolytes like sodium and potassium, magnesium, calcium and b vitamins.2 Supplementation is an option, but no concrete evidence shows supplementing vitamins and minerals provides the same health outcomes as getting them from nutritious food, so I always suggest food first. #2: Ketosis, digestive health, and the microbiome. Beyond constipation that comes from a lack of grains & fibre that result from a keto diet, the impacts of a long-term high fat/low carb diet on the microbiome are of my greatest concern. Without dietary fibre, people on the Keto diet can experience either diarrhea or constipation, as well as bloating. Sometimes these are transient side effects, and other times not. However, dietary fibre is the key ingredient to a microbiota-accessible carbohydrate (or MAC) diet. Fibre is what feeds our flora, which they then convert it short-chain fatty acids like butyrate that provide us with the endless health benefits we hear about surrounding probiotics. Without fibre, our flora suffers, which is demonstrated in the literature looking at all fibre-deficient diets, including FODMAP and gluten-free diets.3 Even short-term ketosis reveals a “statistically significant increase in Desulfovibrio spp, a bacterial group supposed to be involved in the exacerbation of the inflammatory condition of the gut mucosa-associated to the consumption of fats of animal origin”.4 To vastly oversimplify the research, it seems the benefits of the ketogenic diet on the microbiota as a whole are unclear. Some studies show a favourable increase in beneficial flora, while others show the opposite. In summary, the take-home seems to be that an overall decrease in microbial diversity is seen in those following a ketogenic diet.3 #3: The Keto diet can worsen athletic performance, and maybe even long-term weight loss Losing fat sounds great when you want to get fit. However, recent research found that in a ketogenic state, study participants performed worse on running and high-intensity cycling tasks after being on the Keto diet for four days, compared to participants that spent the same four days following a high-carb diet.5 The conclusion of the study suggests “short-term low-carbohydrate, ketogenic diets reduce exercise performance in activities that are heavily dependent on anaerobic energy systems. These findings have clear performance implications for athletes, especially for high-intensity, short-duration activities and sports”.5 Therefore, you may wish to again if you’re considering using the ketogenic diet to fuel your HIIT workouts every morning. Recent studies have also highlighted that “ketogenic diets impair glucose and lipid metabolism in mice” 6, suggesting that long-term use may actually alter metabolic activity. There may also be concerns around the “yo-yo” effects of the Keto diet (where people lose fat, only to gain it back, and oftentimes more) on long-term metabolism. #4: Following the Keto diet long-term can increase the risks of chronic diseases. Since fat consumption is essential to fueling ketogenesis, participants need to consume foods with high-fat content to maintain a ketogenic state. As a result, a rise in cardiovascular risk factors is often seen. Some literature shows an increase in blood pressure and cholesterol levels in ketogenic states, which is something I also see demonstrated in blood work for my current patients on a ketogenic diet. A study from the American College of Cardiology found that people following the Keto diet long-term had a higher risk of developing atrial fibrillation, a common heart rhythm disorder that also increases risks of heart disease and strokes.7 Other literature also highlights adverse effects including hepatic steatosis, hypoproteinemia, and kidney stones.1 In conclusion, it’s safe to say the use of a ketogenic diet needs to be evaluated on a case-by-case basis, and there calls for a collection of better long-term safety research before the diet can be considered as an ongoing intervention. With your microbiome always at the forefront of my mind, short-term ketosis may result in some favourable shifts in weight and metabolism, but offsetting the long-term impacts should be discussed with your ND. To find out more about the right dietary adjustments for your gut and metabolism, please feel free to contact Toronto naturopathic doctor, Dr. Courtney Homberg at 647-351-7282 to schedule your appointment today. Sources:

  1. Masood W, Annamaraju P, Uppaluri KR. Ketogenic Diet. [Updated 2020 Dec 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-.

  2. https://www.health.harvard.edu/staying-healthy/should-you-try-the-keto-diet#:~:text=Other%20potential%20keto%20risks%20include,and%20C%2C%22%20McManus%20says.

  3. Reddel S, Putignani L, Del Chierico F. The Impact of Low-FODMAPs, Gluten-Free, and Ketogenic Diets on Gut Microbiota Modulation in Pathological Conditions. Nutrients. 2019;11(2):373. Published 2019 Feb 12. doi:10.3390/nu11020373

  4. Tagliabue A, Ferraris C, Uggeri F, Trentani C, Bertoli S, de Giorgis V, Veggiotti P, Elli M. Short-term impact of a classical ketogenic diet on gut microbiota in GLUT1 Deficiency Syndrome: A 3-month prospective observational study. Clin Nutr ESPEN. 2017 Feb;17:33-37. doi: 10.1016/j.clnesp.2016.11.003. Epub 2016 Dec 18. PMID: 28361745.

  5. Wroble KA, Trott MN, Schweitzer GG, Rahman RS, Kelly PV, Weiss EP. Low-carbohydrate, ketogenic diet impairs anaerobic exercise performance in exercise-trained women and men: a randomized-sequence crossover trial. J Sports Med Phys Fitness 2019;59:600-7. DOI: 10.23736/S0022-4707.18.08318-4

  6. Li Y, Yang X, Zhang J, Jiang T, Zhang Z, Wang Z, Gong M, Zhao L, Zhang C. Ketogenic Diets Induced Glucose Intolerance and Lipid Accumulation in Mice with Alterations in Gut Microbiota and Metabolites. mBio. 2021 Mar 30;12(2):e03601-20. doi: 10.1128/mBio.03601-20. PMID: 33785628; PMCID: PMC8092315.

  7. https://www.acc.org/about-acc/press-releases/2019/03/06/10/29/low-carb-diet-tied-to-common-heart-rhythm-disorder



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