6 Possible Side Effects of the Ketogenic Diet

Naturally, different people with different eating habits and lifestyles will feel differently when changing over to ketosis.  Some people will have no side effects, while others will experience them immensely for a few days.

During the initial transition, these side effects are called the keto flu.  We have previously discussed the keto flu so those side effects will not be discussed in this article.  There are other potential side effects that occur over weeks and months while on keto.

Side Effects of the Ketogenic Diet

High Fat Leading to Diarrhea

Coconut oil and MCT oil can be used as an energy supplement to quickly increase ketone production.  This could be used in the mornings or before exercise when you need an extra boost of energy.  When eating coconut oil and MCT oil by themselves, diarrhea and/or upset stomach can occur.  You need to ease your body into using these as an energy supplement to determine your level of tolerability.

This could be used to your advantage though if you notice you are suffering from the below side effect of constipation.  A tablespoon of coconut oil in your keto coffee in the morning could do the trick.

Low-Grade Acidosis

It's natural when beginning a keto diet to eat a high amount of foods that are acidic like meats and dairy.  This can turn into heart burn, upset stomach and/or gastroesophageal reflux.

Prevent this by eating plenty of alkaline vegetables like spinach and cauliflower, or nuts like almonds and almond milk.


Similar to the causes of low-grade acidosis, if you're not eating enough vegetables you may not get enough fiber.  This will definitely increase your chances of constipation.

Prevent constipation by eating high fiber/low carb foods like whole avocados or vegetables.  Or supplement your diet with a fiber supplement like psyllium husk.  Another option is to take a magnesium supplement with a laxative effect like this one (sadly your when it has a laxative effect, your body isn't absorbing a lot.  If you want magnesium supplement for actual magnesium absorption, check out our keto supplements guide).


Dehydration does not usually occur after the first week of the diet, but it is possible.  You should be drinking a lot of water on the keto diet, especially if you're exercising.  We also recommend supplementing your water with extra salt, especially around exercise times.

Cholesterol Levels

Over the long term, a benefit of the ketogenic diet is that it will actually decrease your total cholesterol levels while increasing your good cholesterol.  However it is important to note that there may be an initial increase in cholesterol and free fatty acids over the first 1-2 weeks.  After these first few weeks the benefits of cholesterol reduction should take place.

Development of Kidney Stones

There have been research studies[i] on children on ketogenic diets that specifically note that some children developed kidney stones while on the diet.  This would be a very unpleasant side effect of the keto diet.

A separate study[ii] did conclude that by taking a potassium citrate supplement, these kidney stones can be prevented.

People Who Should Not Try The Ketogenic Diet

There are also people with specific conditions that should not try the ketogenic diet because their body will not tolerate it well.

Patients with Kidney Disease

A ketogenic diet is not a high protein diet.  However, some new keto dieters end up increasing their protein as a result of eating less carbohydrates. [iii]   One drawback of this is that a high protein diet can have unhealthy side effects.  But the main concern is for those with kidney disease, or kidney damage.

A person with kidney disease should not increase their protein in-take on the ketogenic diet.  Anyone with damage to kidneys should be aware of their protein intake and not be changing their diet to any more protein than recommended by their doctor.

The ketogenic diet is high fat, not high protein, so you are still able to succeed on the keto diet with lower protein consumption.

Patients with Type-1 Diabetes

The keto diet can be useful in treating patients with Type-2 diabetes.  But those with Type-1 diabetes are in a different boat.  The ketogenic diet should NOT be used for people with type-1 diabetes.

Women who are Breastfeeding

We do not recommend the use of the ketogenic diet for women who are breast-feeding.  There has not been enough research on the keto diet to conclude that it is healthy for both the mother and the baby.

  READ NEXT: Top 8 Things to Know About Keto for Newbies



[i] Kang HC, Chung DE, Kim DW, Kim HD. "Early- and late-onset complications of the ketogenic diet for intractable epilepsy."

[ii] McNally MA, Pyzik PL, Rubenstein JE, Hamdy RF, Kossoff EH.  "Empiric use of potassium citrate reduces kidney-stone incidence with the ketogenic diet."

[iii] A Paoli, A Rubini, JS Volek and KA Grimaldi, "Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets"


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