What are the Side-Effects of the Keto Diet?

side effects

Many remarkable health benefits come with adopting a low-carb ketogenic diet such as to lose weight, have decreased cravings and even possibly reduce the risk for diseases. With that being said, it’s also good to talk about the possible ketosis side-effects when ingesting any weight loss product to supplement the whole diet, so you know entirely what to expect when you get started on this mission.

If you’ve already heard about some of the side-effects that come with this special diet and are starting to freak out, don’t panic. We’re going to break down everything you need to know when it comes to what your body will experience when using these weight loss products for the first time.

What Side-Effects Can We Expect from Ketosis?

It’s important to remember, not everyone experiences ketogenic diet side-effects when starting this new lifestyle and thankfully, the symptoms are all very temporary, and it can pass very quickly. These problems vary with every individual, but to make sure all your bases are covered, we’re going to break down each possible keto side effect that you could experience.

1. Flu Symptoms

Within the first 2-4 days of beginning this lifestyle change, a common keto diet side-effect is known as the “keto flu” or “induction flu” because it has flu-like symptoms. This means you might experience:

  • Headaches
  • Lethargy
  • Lack of motivation
  • Brain fog or confusion
  • Irritability

Although these symptoms typically go away completely within a few days, they are also completely avoidable if you stay very hydrated and increase your sodium intake and like always, be sure you're eating enough healthy fats. 

2. Dizzyness & Drowsiness

As you start dumping water, you'll lose minerals such as sodium, potassium and magnesium. Having lower levels of these minerals will make you feel tired, lightheaded or dizzy. You may also experience leg cramps, headaches and skin itchiness.

Fatigue and dizziness are the most common ketogenic diet side-effects when you're on the diet and they can be avoided for the most part by making sure you stay ahead of mineral loss. You can do this by eating or sipping more salty things throughout the day and eating potassium rich foods. Green leafy vegetables, dairy and avocados are high in potassium and a good place to start.

3. Low-Blood Sugar

For most people, adapting to this process can be hard because people are used to eating a higher carb meal. Your body is used to putting out a certain amount of insulin to take care of the sugar which gets created from all that carbohydrate intake. When you suddenly drop your carbs on this special meal plan, you may have some transient low blood sugar episodes that will feel very scary.

Low Blood Sugar

Just remember don't freak out, if this happens, it's okay to increase your carb intake in the beginning stages to allow your body to level out and adapt easier. If you do happen to have a cheat session, make sure to follow up with a quick consumption of an exogenous ketones supplement to make sure you don't get knocked out of ketosis.

4. Sleep Issues

Some people say that they find it hard to sleep when on the lifestyle. This may be an indication that insulin and serotonin are low. You could try this little trick. Eat a snack which contains both protein and some carbohydrate right before bed. The carbohydrate will increase insulin, which will allow more tryptophan from the protein to get into the brain to allow you to sleep easier.

5. Frequent Urination

After the first day, you'll probably notice that your body will force you to urinate more often. Your body is burning up the extra glycogen in your liver and muscles. Breaking down glycogen releases a lot of water. So, as your carb consumption and glycogen stores drop, your kidneys will start dumping this excess water. This is one of the very common side effects of keto diets.

Frog on Toilet

Besides, as your circulating insulin levels drop, your kidneys start excreting excess sodium, which will also cause more frequent urination.

6. Constipation

This is another one of the most common ketogenic diet side-effects and is usually a combination of dehydration, sodium loss, overeating dairy or too many nuts, or possibly magnesium imbalances. If 400 mg of magnesium citrate isn't helping, you may want to cut back on your dairy product consumption to rebalance your calcium intake to your magnesium intake, drink lots more water or cut back on many nuts you are eating.

7. Diarrhea

This side-effect of ketogenic diet is not unusual and should resolve itself over a few days. Diarrhea can happen just because of the change in routine, or if an unwise decision is made to also limit fat consumption on a low carb meal plan, which results in eating too much protein.


Make sure you replace the carbs you are cutting with more fat, preferably saturated fat such as butter, coconut oil, or preferably  MCT oil to avoid these ketosis side effects.

8. Muscular Cramps

Loss of minerals when first starting the keto diet can cause muscle cramps, especially leg cramps in some people. Like with other keto diet side-effects we’ve mentioned, drinking lots of water and eating things that have sodium can help by preventing cramps and reducing mineral loss.

9. Smelly Breath

If you’re on this diet or have been on it before, you are probably aware that as the body starts to metabolize fat, being in the state of ketosis can cause dry mouth and poor breath. There is tiny one can do about this ketogenic diet side-effect, it’s just the nature of the beast. Unfortunately, this can also arise when using certain products, but it’s not as lasting as when on this type of diet.

Chewing gum or mints is about the best option if it becomes a noticeable issue. This may be caused by over-consumption of some certain weight loss products, tailoring the quantity consumed may prevent excess BHB being converted to acetone, which is likely excreted by the lungs.

Man Blowing in Baby Face

10. Heart Palpitations

In the first few weeks of eating low carb, you might notice a slight increase in heart rate. This is probably common in those who usually have low blood pressure. It’s often just due to lack of sodium and water, causing a reduction in the fluid circulating in the blood. This may then cause the heart to pump slightly faster or harder. So again, drink, drink, drink, and put sodium in your foods. This problem should go away within a week or two, but if you need to after that time, you can slightly increase your amount of carbs.

You might also want to consider a high-quality multivitamin containing zinc, selenium, and a magnesium product to replace any nutrients lost during adaptation to avoid any more side-effects from keto.

11. Brain Fog

For people that do not know what "brain fog" is, let me tell you this, it's not fun. It's when you get forgetful, can't think, and not even be able to communicate correctly. I can remember it happening to me once. I forgot how to go to some place that I've gone to a million times, it's weird. The best description that I can make out of it is like 'mental fatigue.'

There are a few cases where people have reported to experience a "keto brain fog" while on a diet. And, upon digging through them, it could very likely be caused by something else as well. There are health conditions that become more intense when you're are on a completely different routine, that means that your body is trying to adapt to something new which might be causing some ketosis side-effects.

woman with keto brain fog

This is why we always tell people to consult a doctor first before committing to a whole new lifestyle like the ketogenic diet. Anyway, there hasn't been any confirmation that being on the lifestyle can cause keto brain fog which is why we didn't include it in our list of ketogenic diet side-effects. 

There are even more cases as well as research supporting that it can potentially be alleviated through the use of most keto supplements. Dr. Bill Lagakos has caused quite a stir upon releasing his research on the matter. 

Is there Any Way of Avoiding these Symptoms?

Unfortunately, there is no one method to avoid keto side-effects because everybody is different. As you probably noticed, most of the common side-effects can be helped or eliminated by simply doing these things:

  • Drinking more water
  • Increasing your sodium intake
  • Making sure you're eating enough fat
  • Taking products that encourage the body to go into ketosis

3 Main Types of Products That Help With Symptoms:

When your body doesn't ingest carbohydrates, it creates ketones for energy, typically from stored fat. However, there are also ways to get them easily from external sources, meaning coming from outside the body.

The three different types that your body runs on are; Acetoacetate, Beta-Hydroxybutyrate, and Acetone. Beta-hydroxybutyrate is the active form that can flow freely in the blood and be used by your tissues, so that is the one that most of these products are mostly based off.

Keto Foods

When you're experiencing side effects from keto, it's usually from a lack of the precious compounds themselves. This is where ingestible ketones come into play.

1. BHB Crystals

While these crystals may not raise ketone levels to an absurd amount like esters, the taste is much more manageable, and the potential diarrhea side-effects are lessened to a significant degree. For the majority of the population, this is the type of product they should be looking for.

This is where the chemical (again, typically beta-hydroxybutyrate) is bound to a crystal — sodium, calcium, or potassium.

This is the go-to product for help with most of the keto side-effects listed above, especially dehydration, cravings, and flu symptoms.

Peaches and Cream Flavor

2. Esters

Esters are the raw ketone (in this case, beta-hydroxybutyrate) that is not bound to any other compound. This external compound can be utilized a little quicker and potentially have a better effect at raising blood ketone levels as your body doesn’t have to cleave the BHB from any other compound. The downside to esters, is that they just might well be the worst tasting thing on the planet, which is why we recommend the above type first.

3. MCT Oil

MCT (medium chain triglyceride) oil and another medium to smaller chain fats can be used to help boost the compounds in your body as well. However, this is through an indirect pathway. Whereas BHB from crystals or esters can be immediately used for energy, MCT's have to be shuttled to cells to be broken down, which then ketone bodies are made as a byproduct, only then can be used for energy.

Bulletproof Brain Octane

The downsides is that they do little in raising the actual blood levels of ketones. Also MCT oil is quite calorically dense, meaning that it’s not a great solution for those looking to keep calories low and burn fat.

But it does indeed help with muscle cramps, dehydration, appetite control and other keto diet side effects.


Our Final Thoughts

If you do still struggle with keto diet side-effects, as a last resort would be to slightly increase the amount of carbs you’re eating to alleviate symptoms. The downside to this is that it will make your low-carb diet effective less quickly, but sometimes that’s necessary to continue it over the long-term and improve your health.

Overall, do your best to continue following the correct guidelines while also listening to your body and you'll be safe and burning fat at no time.  When the going gets tough, use proper supplementation to reduce the temporary adverse effects of the lifestyle.  If you want to know more about what keto products are out there and what are the best ones, check out our page here

About the Author

Ryan is a personal trainer, athlete, health enthusiast, and entrepreneur. He is researching and expanding his knowledge about the ketogenic diet. He spends most of his time writing content about his new learnings of the ketogenic diet.