ketogenic diet study

Ketogenic Diet Study: Keto Diet Diversifies Gut Bacteria, Jury Still Out On Weight Loss

Thryve Inside recently conducted several internal studies about which type of diet would be most conducive to optimal gut health. Switching to a ketogenic diet saw the second-highest overall increase in stomach bacteria, falling just behind a juice cleanse diet. While many of the stomach bacteria that grew were beneficial for overall health, our results didn’t point to a keto diet plan correlating with weight loss. Let’s take a look at the health benefits of a high-fat, low-carb diet and the results of our keto diet study.


Ketogenic Diet Study Methodology

Our Thryve Inside keto diet study was conducted in three phases over an eight-day period. Phase A saw four volunteers consume their typical Western diet with normal food intake portions. They followed this protocol for two days.
In Phase B, the participants switched to a new diet in the form of the ketogenic diet. They followed this protocol for three days, before finishing the study with three days of their regular diet.
Every day of this keto diet study, we sampled the gut biome of our participants and recorded their averages. Let’s take a closer look at how the ketogenic diet works so you can understand how adopting a new diet that follows these rules might improve your gut health.


Keto Diet Explained

In principles, the keto diet (or South Beach Diet) is a lot like the Atkins Diet that blew up a few decades ago. It involves an extremely low-carbohydrate food intake. Instead, you fill the void with a lot of fat.
This change-up also switches gears in terms of our metabolic processes. After all, our main source of energy comes from glucose derived from carbohydrates. Unfortunately, over 15% of us are physically inactive [1]. So, chances are the average person won’t burn the majority of their carbs off. That’s why keto diet enthusiasts insist a high-carb diet leads to weight gain.
A lack of carb intake in a ketogenic diet alters how we produce energy. In a low-carb diet, our body will turn to its backup reserve. The liver will make up for a lack of energy by secreting ketone bodies. Ketones will become our new main source of energy.
One analysis of ketone bodies as the main source of energy in lieu of less glucose noted,

“Classic studies of ketosis induced by fasting or starvation in humans showed that brain function was maintained which was attributed to the utilization (oxidation) of ketone bodies as alternate energy substrates to glucose by the brain [2].”

Adv Exp Med Biol
Our liver makes ketone bodies from fatty acids stored from a high-fat diet. So, by eating fewer carbs and upping the grams of fat in your food intake, you will naturally lower carb (glucose) intake and increase the production of ketone bodies.
By rights, following this protocol should help with instances of high blood pressure and preventing type 2 diabetes. However, there are some complications with this theory that make it challenging for everybody to follow a keto diet. We’ll discuss that a bit further later.


A State of Ketosis and Intermittent Fasting

As another aside, many people also achieve a state of ketosis through intermittent fasting. That’s why advocates of the keto diet incorporate intermittent fasting into their lifestyle.
intermittent fasting for gut health
Learn more about intermittent fasting
Restricting calories is just like following a low-carb diet…because you’re eating no carbs at all. Can’t get much lower than that! You’re also giving your body a break from having to digest solid food particles.
The empty system looks for a new main source of energy. It will enter a state of ketosis, and the liver will secrete ketone bodies to power the body.
When people break a fast, they tend to fill up on high-fat foods, as they are rich in fatty acids that act as the building blocks of life. These amino acids will have a clear playing field to help improve your overall health.


What Can You Eat on the Keto Diet?

Following a ketogenic diet isn’t as restrictive as intermittent fasting. It’s actually not very restrictive at all. “Restrictive” is a state of mind. There are plenty of options available in a keto diet plan that are absolutely delicious.
You can eat the following foods while following a keto diet:
• Low-Carb Vegetables (Asparagus, Broccoli, Brussels Sprouts)
• Seafood with 0g Net Carbs (Wild-Caught Salmon, Raw Tuna, Halibut)
• Seafood with Low Net Carbs (Clams, Oysters, Mussels)
• Grass-Fed Meat
• Free-Range Poultry
• Grass-Fed Butter
• Cage-Free Eggs
• Avocados
• Greek Yogurt
• Dark Chocolate and Cacao
• Healthy Fruit Oils (Avocado, MCT, Coconut, Extra Virgin Olive Oil)
• Butter and Heavy Cream
As you can see, there are many options to choose from. However, as our results will show, the choices you make within these limitations will determine whether or not weight loss occurs.


Ketogenic Diet Study Results

Our results to the internal ketogenic diet study found that following this new meal plan can significantly alter your gut bacteria. The dramatic change in diversity that happens after just three days of a keto diet will see your body teeming with stomach bacteria that are essential for weight loss. Let’s take a look at some of the results that we found during our ketogenic diet study.


Increases Stomach Bacteria Diversity

We found two interesting ways the keto diet influenced our vounteers’ gut bacteria. Changing from a regular diet to a ketogenic diet saw the second-highest increase in overall diversity. Our test subjects saw a 78% increase in intestinal flora diversity during Phase B. They subsequently saw just as much of a drop during the Phase C portion.
gut bacteria diversity thryve diet studies
A keto diet seemed to have a huge impact in diversifying our volunteers’ guts
Increasing stomach bacteria diversity is essential for improving your overall health. It’s like your gut biome is a football team. Every player has a role that supports other players. Yet, they also have their own unique traits that make them an irreplaceable member of the roster.
Each stomach bacteria may have characteristics that overlap with one another, but they also have unique specialties that make them essential members of our gut biome roster.
A meta-analysis about the importance of stomach bacteria diversity stated,

“Lower diversity is considered a marker of dysbiosis (microbial imbalance) in the gut and has been found in autoimmune diseases and obesity and cardiometabolic conditions [3].”

British Medicine Journal (BMJ)
By following a low-carb and high-fat diet, your body will promote the growth of different stomach bacteria. Therefore, a ketogenic diet might help alter your gut biome for the better.


May Improve Brain Health

By following a low-carb and high-fat diet, your body will promote the growth of different stomach bacteria. Therefore, a ketogenic diet might help alter your gut biome for the better.

ketogenic diet vs mcdonald's diet

A ketogenic diet and McDonald’s diet seem to be reversely related

Interestingly enough, the ketogenic diet had a complete opposite effect. Levels of Parasutterella increased during Phase B. In fact, by looking at the data, it looks like the same line graph upside-down.
Until recently, not much was known about Parasutterella, other than the fact that too much of it can have a negative impact on weight [3]. However, when the microbiome is balanced and diverse, like it appears to be under a ketogenic diet, Parasutterella seems to have benefits.
A new study uncovered that Parasutterella might regulate inflammation in the hypothalamus [4]. This part of the brain responsible for our hormone production. Fighting off inflammation in this area might be beneficial for fertility, mood, and maintaining sleep cycles.


Might Help Fight Irritable Bowel Disease (IBD)

Eating fewer carbs and consuming a high-fat diet seems to have some benefits for the digestive system. For one, it produced higher levels of Bacteroides. This genus of stomach bacteria are some of the most common in our gut. So, our body relies on them to function optimally. Otherwise, the system becomes prone to stress, and ultimately, inflammation.
A meta-analysis of Bacteroides and Irritable Bowel Disease concluded,

“We identified 63 articles, 9 of which contained sufficient data for evaluation. The mean level of Bacteroides was significantly lower in Crohn’s disease (CD) and ulcerative colitis (UC) patients in active phase than in normal controls [5].”

Hindawi Biomed Research International
One of the reasons we believe following a classic ketogenic diet has these benefits is because it’s a high-fat diet. Healthy fats contain plenty of collagen and elastin. These proteins help give structure to the cells that line your gut. That way, you are less likely to cause inflammation in the GI tract. That’s why consuming bone broth is a very popular choice for those following this type of diet.


May Combat Autoimmune Disease

We tested the gut bacteria of two volunteers to get a snapshot of levels of Prevotella while following a keto diet plan. The two test subjects saw levels of this stomach bacteria drop around 35% during Phase B.
Prevotella is an essential stomach bacteria for a healthy gut biome. However, too much of this bacteria can lead to long term inflammation.
One meta-analysis on this intestinal flora noted,

“Emerging studies in humans have linked increased abundance of Prevotella species at mucosal sites to localized and systemic disease, including periodontitis, bacterial vaginosis, rheumatoid arthritis, metabolic disorders, and low-grade systemic inflammation [6].”

After Phase C, their gut biome returned to normal. So, continuing a keto diet plan over the long term might be beneficial in preventing autoimmune diseases.


Doesn’t Seem to Benefit Weight Loss

This ketogenic diet study brought upon a shocking revelation. It made the average Bacteroidetes to Firmicutes ratio dip in favor of the latter. Interestingly, an abundance of Firmicutes has been linked to obesity.
firmicutes in ketogenic diet
Levels of Firmicutes seemed to rise in our volunteers
With that said, about 90% of our stomach bacteria are either of Bacteroidetes or Firmicutes species. So, while there seem to be more Firmicutes bacteria in people who are obese, it doesn’t mean skinny people can’t have more Firmicutes than Bacteroidetes in their system.
At the end of the day, there needs to be an abundance of both in the body, and you just need to make sure the Firmicutes don’t get out of control. Based on our analysis, it seems like following a keto diet plan can keep these levels consistent enough to prevent weight gain. However, we don’t have enough data to determine if one of the benefits of the keto diet is weight loss.


Might Promote Bacteria Associated With Insulin Resistance


While ratios of Bacteroides to Firmicutes decreased, one species of this genus experienced a significant rise during our volunteers’ keto diet plan. Amounts of Bacteroides vulgatus saw a 20% jump during Phase B of our ketogenic diet study. These amounts continued to rise as the volunteers entered Phase C.

keto diet study results
Those who follow a keto diet must do so responsibly
Research shows that excess Bacteroides vulgatus may cause a spike in branch-chained amino acids (BCAAs) [7]. When we have too many BCAAs in the system, it makes significant changes to our metabolic processes. For one, excess BCAAs promote insulin resistance [8]. Subsequently, HDL cholesterol levels drop, also making a person at risk for heart disease.
Subsequently, BCAAs are also essential for building muscle. That’s why a keto diet is so popular with weightlifters and CrossFit trainers. If you’re putting these BCAAs to good use they’re a tool. However, if you let them linger, they can be detrimental to your health.


Why Keto Diet Is Bad For Some People

Seeing these results may cause someone not to try a keto diet. However, the benefits of a ketogenic diet should include improving type 2 diabetes. After all, most people who have diabetes are encouraged to follow a low-carbohydrate diet.
Whether you have type 2 diabetes or not, you should talk to your doctor about proper nutrition before trying a new diet. However, both parties should be able to follow a keto diet and improve their overall health. The issues lie in too much fat from unhealthy sources.
A healthy high-fat diet includes:
chia seeds for ibs
• Coconut Oil
• MCT Oil
• Extra Virgin Olive Oil
• Nut Butters
• Avocados
• Wild-Caught Fish
• Cheese
• Eggs
• Nuts
Of course, you can have your beef and lamb. However, these should be eaten in moderation. When analyzing four volunteers with their own taste preferences, their high-fat diet may not have had enough of the above-mentioned keto diet foods.
We believe our data doesn’t say a keto diet directly causes type 2 diabetes or heart disease. It just proves as a warning sign that we must be vigilant with the foods we choose. Just because you’re following the right guidelines doesn’t mean you’re eating the correct items. We must eat as many whole foods as possible and include more plant-based options to receive benefits of the keto diet.


Does the Keto Diet Work?

Our study is intended to provide a short-term look at what happens when someone switches from their usual grub to following a keto diet plan. We can’t determine with our results if the keto diet can aid in weight loss or prevent heart disease over the long-term. All we can do is see what happens to the gut bacteria over three days and use that to hypothesize these bacterias’ future trajectories.
What we can determine is that a ketogenic diet does promote gut bacteria diversity. Consuming a high-fat diet can improve gut lining and brain health. However, the quality of those foods can put you at risk, especially if you have underlying medical conditions. So, be sure you are educated about the proper foods to eat in a keto diet plan. Then, you can feel the true benefits of a keto diet.


Click Here To View Resources



[1] Shraddha Chakradhar, et al. “More than 15% of U.S. Adults Are Physically Inactive, New CDC Data Show.” STAT, 17 Jan. 2020,
[2] LaManna, J. C., Salem, N., Puchowicz, M., Erokwu, B., Koppaka, S., Flask, C., & Lee, Z. (2009). Ketones suppress brain glucose consumption. Advances in experimental medicine and biology, 645, 301–306.
[3] Zeng, Qiang, et al. “Discrepant Gut Microbiota Markers for the Classification of Obesity-Related Metabolic Abnormalities.” Nature News, Nature Publishing Group, 17 Sept. 2019,
[4] Ju, Tingting, et al. “Defining the Role of Parasutterella , a Previously Uncharacterized Member of the Core Gut Microbiota.” Nature News, Nature Publishing Group, 11 Feb. 2019,
[5] Zhou, Yingting, and Fachao Zhi. “Lower Level of Bacteroides in the Gut Microbiota Is Associated with Inflammatory Bowel Disease: A Meta-Analysis.” BioMed Research International, Hindawi, 24 Nov. 2016,
[6] Robert Glatter, MD. “Imbalance Of Gut Bacteria Linked To Elevated Risk For Diabetes.” Forbes, Forbes Magazine, 22 July 2016,
[7] Karusheva, Yanislava, et al. “Short-Term Dietary Reduction of Branched-Chain Amino Acids Reduces Meal-Induced Insulin Secretion and Modifies Microbiome Composition in Type 2 Diabetes: a Randomized Controlled Crossover Trial.” OUP Academic, Oxford University Press, 27 Aug. 2019,
[8] Larsen, Jeppe Madura. “The Immune Response to Prevotella Bacteria in Chronic Inflammatory Disease.” ResearchGate, May 2017, Immunology 151(4).

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