What are the Side-Effects of the Keto Diet?


There are many awesome benefits that come with adopting a low-carb ketogenic diet, such as weight loss, decreased cravings and even possibly reduce disease risks. With that being said, it’s also good to talk about possible ketosis side-effects when ingesting these specific ketone supplements, so you know fully 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 supplements for the first time.

What Side-Effects Can We Expect from Ketosis?

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

1. Flu Symptoms

Within the first 2-4 days of beginning this diet, a common side-effect is known as the “ketosis flu” or “induction flu” because it mimics the symptoms of the actual flu. 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 salt intake and like always, be sure you're eating enough fat. 

2. Dizzyness & Drowsiness​

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

Fatigue and dizziness are the most common side-effects when taking these supplements and they can be avoided for the most part by making sure you stay ahead of mineral loss. You can do this by eating more salt or sipping salty broth 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

Low Blood Sugar

For most people adapting to this process can be hard because people are used to eating a higher carb diet. 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 carb intake on this special diet plan, you may have some transient low blood sugar episodes that will feel very scary.

Just remember don't freak out, if this happens, it's ok 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 intake 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 a ketogenic diet. 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

Frog on Toilet

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 intake and glycogen stores drop, your kidneys will start dumping this excess water.

In addition, 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 low carb diet side-effects and is usually a function of dehydration, salt loss, eating too much 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 a number of nuts you are eating.

7. Diarrhea


This side-effect is not unusual and should resolve itself over a few days. It can happen just because of the change in diet, or if an unwise decision is made to also limit fat intake on a low carb diet, 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.

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 side-effects we’ve mentioned, drinking lots of water and eating salt can help by preventing cramps and reducing 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, ketones can cause dry mouth and poor breath. There is very little one can do about this, it’s just the nature of the beast. Unfortunately, this can also arise when using exogenous ketones, 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 maybe caused by over consumption of the exogenous supplement, tailoring the quantity consumed may prevent excess BHB being converted to acetone, which is likely excreted by the lungs.

10. Heart Palpitations

In the first few weeks of eating low carb, you might notice a slight increase in heart rate. This is probably more common in those who normally have low blood pressure. It’s often simply due to lack of salt 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 salt 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 and selenium and a magnesium supplement to replace any nutrients lost during adaptation.

11. Brain Fog​

woman with keto 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 properly. 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 the 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 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. Anyway, there hasn't been any confirmation that being on the ketogenic diet can cause keto brain fog which is why we didn't include it in our list of side-effects. 

Having said that, there are even more cases as well as research supporting that brain fog 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 salt intake
  • Making sure you're eating enough fat
  • Taking exogenous ketone supplements

3 Main Types of Exogenous Ketones:

Keto Foods

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

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

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

1. BHB Salts

Peaches and Cream Flavor

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

​One form of exogenous supplement comes in the form of ketone “salts.” This is where the ketone body (again, typically beta-hydroxybutyrate) is bound to a salt — sodium, calcium, or potassium.

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


2. Esters

Ketone esters are the raw ketone (in this case, beta-hydroxybutyrate) that is not bound to any other compound. This exogenous supplement 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 BHB salts above.

3. MCT Oil

Bulletproof Brain Octane

MCT (medium chain triglyceride) oil and other medium to smaller chain fats can be used to help boost ketones as well. However, this is through an indirect pathway. Whereas beta-hydroxybutyrate from salts 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.

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, and appetite control.


Final Thoughts:

If you do still struggle with symptoms, 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.

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

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