What are the Side-Effects of the Keto Diet?

side effects

Many remarkable health benefits come with adopting a low-carb ketogenic diet.

Some of them are losing weight, having decreased cravings and even possibly reducing the risk of 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'd 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?

man having a headache

It’s important to remember that not everyone experiences ketogenic diet side-effects when starting this new lifestyle and thankfully, the symptoms are all very temporary and can pass very quickly.

These problems vary with every individual, but just to make sure that all your bases are covered, we’re going to break down every possible keto side effect that you can ever experience.

1. Flu Symptoms

Lady with flu

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

This means that you might experience:

  • Headaches
  • Lethargy
  • Lack of motivation
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    Brain fog or confusion
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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. It also helps to make sure you're eating enough healthy fats.

2. Dizziness & Drowsiness

man sitting and holding head

As you dump water while on the diet, you're going to be losing minerals such as sodium, potassium and magnesium.

Having lower levels of these minerals in your body will make you feel tired, lightheaded or dizzy.

You may also experience leg crampsheadaches and skin itchiness.

Fatigue and dizziness are the most common ketogenic diet side-effects  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. You can also eat potassium-rich foods. Green leafy vegetables, dairy, and avocados are high in potassium and are a good place to start.

3. Low Blood Sugar

block on sugar on spoon

For most people, adapting to this process can be hard because they're 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 that 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. 

Just remember to not 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 go on a cheat session, make sure to quickly take an exogenous ketones supplement afterward to make sure you don't get knocked out of ketosis.

4. Sleep Issues

man can't sleep

Some people say that they find it hard to sleep when on the lifestyle.

This may be an indication that insulin and serotonin levels are low.

You could try this little trick: eat a snack which contains both protein and carbohydrates right before bed. 

The carbohydrate will increase insulin levels, which will allow more tryptophan from the protein to get into your brain, which will then allow you to sleep easier.

5. Frequent Urination

a constipated boy

After the first day, you'll probably notice that your body will force you to urinate more often.

This is due to the fact that your body is burning up the extra glycogen in your liver and muscles.

We know that 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 the keto diet.

Also, as your circulating insulin levels drop, your kidneys will 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 of dairy or nuts, or even possibly magnesium imbalances.

If 400 mg of magnesium citrate isn't helping, you may want to cut back on your dairy consumption to rebalance your calcium intake to your magnesium intake.  

You will also do good to drink more water and cut back on the nuts you're eating.

7. Diarrhea

man suffering from diarrhea

This side-effect of the 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 with  saturated fat such as butter, coconut oil, or  MCT oil to avoid these ketosis side effects.

8. Muscular Cramps

man experiencing leg cramps

Loss of minerals when first starting the keto diet can cause muscle cramps, especially leg cramps, in some people.

Similar to the other keto diet side-effects we’ve mentioned, drinking lots of water and eating things that have sodium can help prevent cramps and reduce mineral loss.

9. Smelly Breath

Man Blowing in Baby Face

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 actually cause dry mouth and poor breath.

There is nothing 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 when you're on this type of diet. Chewing gum or mints is about the best option for you if it becomes a noticeable issue. Bad breath may be caused by over-consumption of some certain weight loss products, so tailoring the quantity of your consumption of those products may prevent excess BHB from being converted to acetone (which is likely excreted by the lungs, thereby causing your breath to smell bad).

10. Health Palpitations

diagnosis palpitations

You might notice a slight increase in heart rate in the first few weeks of eating a lower amount of carbs. This is probably common in those who usually have low blood pressure.

It’s often just due to a 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 water, and add more sodium to your  food. This problem should go away within a week or two, but if you need to lessen the time that it takes, then you can slightly increase your carb intake.

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

11. Brain Fog

man experiencing brain fog

For people who 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 properly, and can't even 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, and I can definitely say that it's really weird. 

The best description that I can give to it is something like "mental fatigue." There are some cases of people reporting to having experienced "keto brain fog" while on the diet.

However, upon digging through those reports, I can say that there's a chance it could be caused by something else as well. There are health conditions that become more intense when you're are on a completely different routine, which means that your body is trying to adapt to something new. This might be the one that's causing some of these ketosis side-effects.

This is why we always tell people to consult a doctor first before committing to a whole new lifestyle like the ketogenic diet. Also, there hasn't been any confirmation that being on the lifestyle can cause keto brain fog. In fact, there is research that support the notion that brain fog can potentially be alleviated by using 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 may have probably noticed, most of the common side-effects can be helped or eliminated by simply doing these things:

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

Other Things That Help With Symptoms

fish on a plate white green sidedish

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.

The three different types of ketones 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 can be used by your tissues, so that is the one that most of these products are mostly based off of.

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

1. BHB

While these crystals may not raise ketone levels to an absurd amount like esters, their 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.

Peaches and Cream Flavor

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

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

2. Esters

Esters are the raw ketone (in this case, beta-hydroxybutyrate) that are not bound to any other compound.

This external compound can be utilized a little quicker and can potentially have a better effect at raising blood ketone levels as your body doesn’t have to cleave the BHB from any other compound. 

beta hydroxybutyrate sign

The downside to esters, however, 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 other 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, MCTs have to be shuttled to cells to be broken down, after which ketone bodies are made as a byproduct, and only then can they be used for energy.

Bulletproof Brain Octane

The downside is that they do little in raising the actual blood levels of ketones.

Also, MCT oil is quite calorically dense, meaning it’s not a great solution for those looking to burn fat and keep calories low.

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


Final Thoughts

If you do still struggle with keto diet side-effects, 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 less effective, but sometimes that’s necessary so you can continue the diet 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 burning fat in 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 the best ones are, 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 and shares it on Ketogenic Supplement Reviews. You can find me on: Facebook, Twitter and Pinterest.