The ketogenic diet is a low-carb, high-fat diet that has been linked to many health benefits, including weight loss and preventing age-related mental decline (1).
As this diet grows in popularity, a number of keto-friendly supplements have become available to consumers.
Exogenous ketone supplements are claimed to provide the benefits of a ketogenic diet even when the consumer is not following one.
Prüvit Keto OS is a brand of these supplements marketed for their ability to increase energy, boost athletic performance and reduce appetite.
This article reviews Prüvit Keto OS supplements and explores the evidence behind exogenous ketones.
Keto OS supplements are made by Prüvit, a self-proclaimed worldwide leader in ketone technology.
Keto OS, which stands for “Ketone Operating System,” is an exogenous ketone drink offered in a variety of flavors.
It comes as a powder in both bulk containers and “on-the-go” (OTG) packets and is meant to be dissolved in cold water.
Prüvit recommends that a heaping scoop of Keto OS be mixed with 12 to 16 ounces of cold water and taken once a day for therapeutic benefits or twice a day for “optimal performance.”
What Are Ketones?
Ketones, or “ketone bodies,” are compounds produced by the body as an alternate energy source when glucose (blood sugar) is unavailable to use for fuel (2).
Examples of times when the body produces ketones include starvation, prolonged fasting and ketogenic diets. In these situations, the body goes into a metabolic state called ketosis and becomes very efficient at burning fat for energy.
In a process called ketogenesis, the liver takes fatty acids and converts them to ketones for the body to use as energy.
During times of low blood sugar availability, these ketones become the main energy source for tissues able to break them down, including brain and muscle tissue.
The ketones made during ketogenesis are acetoacetate, beta-hydroxybutyrate and acetone (3).
There are two types of ketones:
- Endogenous ketones: These are ketones made naturally by the body through the process of ketogenesis.
- Exogenous ketones: These are ketones supplied to the body by an external source like a nutritional supplement.
Most exogenous ketone supplements, including Keto OS, use beta-hydroxybutyrate as their exogenous ketone source because it is used most efficiently by the body (4).
What Are Ketone Supplements?
There are two forms of exogenous ketone supplements:
- Ketone salts: This is the form found in most ketone supplements available on the market, including Keto OS. Ketone salts contain ketones that are most commonly bound to sodium, calcium or potassium to increase uptake.
- Ketone esters: Ketone esters are primarily used in research and are not currently available to consumers. This form consists of pure beta-hydroxybutyrate without other additives.
Aside from beta-hydroxybutyrate, Prüvit Keto OS supplements contain caffeine, MCT (medium-chain triglyceride) powder, malic acid, ascorbic acid and the natural, zero-calorie sweetener Stevia.
Prüvit Keto OS supplements are gluten-free but do contain milk ingredients.
Summary Prüvit Keto OS is an exogenous ketone supplement that provides consumers with an immediate source of ketones. The type of ketone found in Prüvit OS supplements is called beta-hydroxybutyrate.
Prüvit claims that Keto OS supplements allow consumers to reach a state of nutritional ketosis within 60 minutes of consuming them.
This may be attractive to those who are turned off by the hard work and dedication it takes to get the body into a state of ketosis through a ketogenic diet, which can take weeks.
The standard ketogenic diet is typically composed of 5% carbohydrates, 15% protein and 80% fat. It can be hard to follow for a prolonged period of time.
Exogenous ketone supplements were created to provide people with a shortcut to reach ketosis and experience its related benefits without having to follow a strict diet or partake in fasting.
In contrast to the slow rise of ketones associated with following a ketogenic diet, drinking an exogenous ketone supplement like Keto OS results in a rapid rise in blood ketones (5).
After being ingested, beta-hydroxybutyrate is absorbed into the bloodstream and then converted into an effective energy source for the body.
The appeal of exogenous ketones is that they raise ketone levels even when the consumer is not in a state of ketosis before ingesting them.
It has been purported that reaching nutritional ketosis through supplementation can deliver the same benefits as reaching ketosis through a ketogenic diet or by fasting. These benefits include weight loss, increased energy and mental clarity.
Summary Exogenous ketone supplements deliver an instant supply of ketones to the body without the need to reach ketosis through diet or fasting.
While the ketogenic diet has been extensively researched and its benefits substantiated, research on exogenous ketones is in its early stages.
However, there are several studies on the potential benefits of exogenous ketones that have had promising results.
May Improve Athletic Performance
Due to the body’s increased need for glucose (blood sugar) during intense training, the glucose-sparing qualities of exogenous ketones may be helpful for athletes.
Low levels of muscle glycogen (the storage form of glucose) have been shown to inhibit athletic performance (6).
In fact, “hitting the wall” is a common term used to describe the fatigue and energy loss related to the depletion of muscle and liver glycogen reserves (7).
Some studies have demonstrated that providing athletes with exogenous ketone supplements may improve athletic performance.
One study of 39 high-performance athletes found that drinking 260 mg of ketone esters per pound of body weight (573 mg/kg) during exercise improved athletic performance.
The athletes in the study who consumed the ketone drink traveled an average of 1/4 mile (400 meters) farther over a half hour than those who consumed a drink containing carbohydrates or fat (8).
Exogenous ketones may also help you recover more quickly after intense workouts by promoting the replenishment of muscle glycogen.
However, exogenous ketones may not be effective for athletes who participate in exercises that require short bursts of energy like sprinting. This is because these exercises are anaerobic (without oxygen) in nature. The body needs oxygen to break down ketones (9).
Additionally, the exogenous ketone supplements currently available on the market contain ketone salts, which are less potent than the ketone esters used in current studies.
Could Reduce Appetite
The ability of the ketogenic diet to reduce appetite and help with weight loss has been demonstrated in many studies (10).
Supplementing with exogenous ketones may be an effective way to reduce appetite, as well.
Ketones can suppress appetite by impacting the hypothalamus, a part of the brain that regulates food intake and energy balance (12).
One study of 15 people found that those who consumed 0.86 calories of ketone esters per pound (1.9 calories/kg) of body weight had significantly less hunger and desire to eat, compared to those who consumed a carbohydrate drink.
May Help Prevent Mental Decline
Ketones have been shown to be an effective alternative fuel source for the brain in times of low glucose availability.
There is also evidence that ketone bodies help reduce neurological damage by blocking inflammasomes, a group of protein complexes that cause inflammation in the body (15).
Supplementing with exogenous ketones has helped improve mental function in many studies, particularly in people with Alzheimer’s disease (16).
Brain glucose uptake is impaired in people with Alzheimer's disease or mild cognitive impairment. Thus, it has been suggested that the gradual depletion of brain glucose can contribute to the progression of Alzheimer’s disease (17).
One study followed 20 adults with Alzheimer's disease or mild cognitive impairment.
Increasing their blood levels of beta-hydroxybutyrate by supplementing with MCT oil — a type of saturated fat that promotes ketone production — led to a greater improvement in cognitive performance, compared to a placebo (18).
Several studies on rats and mice with Alzheimer’s disease have found that supplementing with ketone esters led to improvements in memory and learning, plus helped reduce anxiety-related behavior (19, 20, 21).
May Help You Reach Ketosis More Quickly
However, achieving ketosis by following a ketogenic diet or fasting can be difficult for many people. Exogenous ketone supplements can help you get there more quickly.
Prüvit Keto OS supplements contain both beta-hydroxybutyrate and MCT powder.
Supplementing with both beta-hydroxybutyrate and MCTs has been shown to effectively raise levels of ketones in the blood without the need for dietary change (22).
However, it’s important to note that ketone salts, which are the kind of ketones found in Keto OS, are much less effective at raising ketone levels than ketone esters.
In several studies, supplementing with ketone salts resulted in beta-hydroxybutyrate levels of less than 1 mmol/L, while taking ketone esters raised blood beta-hydroxybutyrate concentrations to 3 to 5 mmol/L (26, 27, 28).
Even though the benefit may be small, exogenous ketone salt supplements like Keto OS do provide a quick boost of ketones.
Recommendations for blood ketone levels vary depending on your goal, but most experts recommend a range between 0.5–3.0 mmol/L.
Those beginning a ketogenic diet sometimes find exogenous ketones to be helpful not only in raising ketone levels but also in reducing symptoms of “keto flu.” These include nausea and fatigue, which sometimes occur in the first weeks of the diet as the body adjusts.
Summary Exogenous ketone supplements may help boost athletic performance, reduce appetite and prevent mental decline. They may also be beneficial for people trying to reach ketosis more quickly.
Although there have been some benefits associated with taking ketone supplements, there are possible risks and unpleasant effects, as well.
- Digestive issues: One of the most common side effects of these supplements is stomach upset, including diarrhea, pain and gas (29).
- Bad breath: When following a ketogenic diet, elevated ketone levels in the body can cause bad breath. This can also happen when taking supplements (30).
- Low blood sugar: Ketone supplements can significantly reduce blood sugar levels, making it important for those with diabetes to consult their doctor before use.
- Expense: Prüvit recommends two servings of Keto OS per day for “optimal performance.” Following this recommendation, two weeks’ worth of Prüvit Keto OS will cost around $182.
- Unpleasant taste: Though ketone salts are much more tolerable to drink than ketone esters, the main complaint of Keto OS consumers is that the supplement has an unpleasant taste.
Additionally, the long-term effects of combining a non-ketogenic diet with exogenous ketone supplements are unknown. More research is needed before potential benefits and risks can be fully understood.
Research on exogenous ketone supplements is limited at this time, and studies on their potential benefits are ongoing.
As more information is discovered through scientific studies, the applications and limitations of exogenous ketones will be better understood.
Summary Potential risks of consuming exogenous ketones include stomach upset, low blood sugar levels and bad breath. Additionally, exogenous ketones are expensive and scientific studies on their efficacy and safety are limited.
Using exogenous ketones, especially by people not following a ketogenic diet, is a new trend.
Some evidence shows that these supplements can boost athletic performance, increase mental performance and decrease appetite, but studies providing conclusive results on the benefits of these supplements are limited.
Hopefully, as the use of exogenous ketones continues to be explored, the potential benefits and risks of using these supplements will be better established.
For people who are already following a ketogenic diet and want to reach ketosis a bit quicker or for athletes looking for a performance boost, an exogenous ketone supplement like Keto OS may be beneficial.
However, due to the limited information on the effectiveness and safety of these supplements as well as the high cost, it may be a good idea to hold off on investing in Keto OS supplements until more scientific studies prove their benefits.
Additionally, most of the studies examined the benefits of ketone esters, not the ketone salts that are found in supplements, like Keto OS, available to consumers.
Although there are some ketone ester products being developed for public consumption, there aren't any available at this time.
Since little is known about the effects that exogenous ketones may have on different people, it’s always best to consult your doctor before taking these supplements.
Summary Exogenous ketone supplements like Keto OS are relatively new products that need to be researched further before conclusive benefits and risks can be confirmed.
The use of exogenous ketones by the general public is a recent phenomenon.
Although there is some evidence that exogenous ketones may be useful in neurological disorders like Alzheimer’s disease, studies on their use in other areas are limited.
A few studies suggest these supplements may benefit appetite suppression and athletic performance, but more research is needed before a conclusion can be made.
Due to the high cost and overall taste of Prüvit Keto OS supplements, it may be best to purchase a few packets to try before investing in several weeks’ worth of supplements.
There may be some benefits to taking Prüvit Keto OS supplements, but the jury is still out on whether supplementing with exogenous ketones really translates to better health.