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.

1. Website: https://www.courtneyholmbergnd.ca/ Phone: (647) 351-7282
THE KETOGENIC DIET AND YOUR
MICROBIOME

2. Website: https://www.courtneyholmbergnd.ca/ Phone: (647) 351-7282
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 premises
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 initially
weight loss of up to 10 lbs in 2 weeks or less.1

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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 provide 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
suffer, 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

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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 include hepatic

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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 collected on better long term safety
research before the diet can be considered as an ongoing intervention. With
your microbiome always being 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