Ketosis side effects – Safety of the ketogenic diet plan

If you have been reading this blog for a while, then you will know that I am a fan of the ketogenic diet plan.

No, I don’t do it myself, and I don’t recommend it for healthy people because I think it is too restrictive.

However, this has been studied in epileptic children, diabetic patients and overweight people with incredible success. I believe this diet plan has a lot of therapeutic potential for these disorders.

In this article I am going to discuss ketosis side effects and the general safety of the ketogenic diet, but there appear to be a lot of misconceptions about it that I would like to dispel.

A picture of Ketosis Side Effects

There are some minor ketosis side effects that you should be aware of

The ketogenic diet plan

When I refer to the ketogenic diet plan, I am talking about a diet that is very restricted in carbohydrates, moderate in protein and high in fat. This diet results in an elevated blood level of ketone bodies.

The “classic” ketogenic diet is a bit different, and is used to treat epileptic children and involves weighing food and calculating calories.

I’ve written an article before describing a sample ketogenic diet menu.

Ketosis is not the same as Ketoacidosis

It is important to distinguish between ketosis and ketoacidosis.

Ketoacidosis is a phenomenon that mainly happens in type I diabetics when they don’t get any insulin for a long time.

This happens because the cells don’t receive any blood sugar without insulin, and therefore the body thinks that it is starving and ramps up ketone body production in an uncontrolled manner.

The ketone level in the blood becomes very high and causes the acidity of the blood to increase. This is very dangerous and can be fatal, but this does NOT happen with low-carbohydrate diets.

Ketosis, however, is the body’s response to fasting, starvation or a very low-carbohydrate diet. It happens because the body isn’t receiving the glucose that it wants, and instead it breaks fat down into ketone bodies in order to use them for energy.

There is nothing unnatural about a healthy amount of ketone bodies, and most cells are able to effectively use them as fuel instead of glucose. The body can produce all the glucose it needs (about 130g) out of amino acids and other substances.

In reality, the human body doesn’t have any actual need for carbohydrates in the diet.

Safety of the ketogenic diet plan for children

I’ve written a compilation of research studies on the ketogenic diet before. To examine their safety, I skimmed through most of these studies, and a few others, to look for adverse effects.

It appears that in children being treated for epilepsy, there is a long-term risk of kidney stones, growth retardation and bone demineralization (1). Using nutritional supplements, such as a blend of vitamins and minerals, should decrease the chances of adverse effects.

It should be noted that those side effects are rarely severe enough to warrant discontinuation of the diet. Generally, the ketogenic diet is very well tolerated in epileptic children.

Parents should never try to treat their epileptic children by themselves, it should be done with the guidance of a neurologist who has an understanding of the possible adverse effects.

Safety of ketosis in adults

There are a lot of misconceptions about this. I’ve even heard one of my university teachers claim that people have been hospitalized because of low-carbohydrate diets.

Well, to put it bluntly, that is crap.

In adults, there are NO indications that a ketogenic diet would be dangerous in any way. A massive review article found that there were no serious adverse events caused by low-carbohydrate or ketogenic diets (2).

You would think that a diet so high in fat would probably cause horrible blood lipids and lead to heart disease. I don’t blame you for thinking that, given the propaganda about saturated fats in the past.

Well, it turns out that the high-fat, low-carb ketogenic diet improves blood lipids and other biomarkers of health, leading to weight loss, lowered blood pressure, decreases in triglycerides, elevated HDL (good) cholesterol, as well as decreasing blood sugar and insulin levels (2, 3, 4, 5).

However, those using any medications do need to consult with their doctors before trying out a ketogenic diet, because it can drastically reduce or even eliminate the need for certain medication, especially in type II diabetic patients (5, 6).

It is also critical to use a multivitamin supplement with this diet to prevent any nutritional deficiencies.

Ketosis side effects

Even though this diet plan has incredible health benefits for many people, there are some side effects that come with it.

I believe that many of those side effects are temporary. When the body suddenly switches its primary fuel, it does need some time to adapt and ramp up enzyme production and such.

That being said, these are a the main ketosis side effects that have been reported:

  • Skin rash
  • Headaches
  • Muscle cramps
  • Diarrhea
  • Constipation
  • Weakness
  • Insomnia
  • Amenorrhea


In both children and adults, there are some ketosis side effects, and anyone with a medical condition should consult with a doctor before trying this out.

This diet plan has been consistently shown in research studies to have massive therapeutic potential for many disorders. These are usually treated with medication, which address the symptoms (not the cause).

These mild ketosis side effects are, in most cases, much less severe than those that come with medication, let alone many years (or a lifetime) of using multiple different drugs.

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  1. I went on a ketogenic diet in August 2010. I lost 15kgs in total before Christmas 2010. I strictly followed the NOT TO EAT list from Monday to Friday. Saturdays and Sundays i allowed myself to cheat. This way i had something to look forward too throughout the diet and it worked. Since then i’ve been eating carbs regularly again but only gained 5kgs. I am starting the diet again as from today to hopefully lose another 10kg to reach my goal weight.

  2. Hi Kris, I began the keto diet on April 1st, and have a substantial amount to lose. I have been eating chicken, salad, green beans, lots of peppers, beef, eggs,cheese and almonds which is great because I love all of these foods. I am missing bananas the most and know that it is time to have the will power to succeed at this as I have failed at many attempts in the past. I was hoping you could advise on the suitability of eggplant, turnip and brussel sprouts as I did not see these listed on any websites I have viewed over the last few weeks. I have also purchased the Body by Vi protein shake mix and was hoping to incorporate that into my diet menu since I have very limited time due to working long hours and meal preparation is becoming challenging. I have lost some weight, but mostly am noticing the change in the fit of my clothing. I guess just some reassurance and suggestions on variety would be greatly appreciated. Thanks

  3. Hi Kristjan,
    Very good article, with some interesting points raised. Thankyou. I’m glad you pointed out that you wouldn’t recommend the ketogenic diet to healthy people, although in terms of ‘restrictive’, I wasn’t sure whether you meant nutritionally so, food variety, or both? I’d have said both myself!

    I do disagree with your point that, our body doesn’t require carbohydrates however. Although this is true for carbs in isolation, its a dangerous statement to make, since its the complex carbs that come with those necessary micro-nutrients, not to mention fibre, our bodies absolutely rely on for ultimate health….and getting them from a pill or a powder just doesn’t cut it. From this stand-point, a low-carb diet can indeed make a person ill over a long period.

    Keto diets are safe if practised safely, although having been strictly ketogenic for a month, I can say that I felt like crap on it most of the time, and was miserable, despite decreasing my BF percentage. I eat a wholefoods diet usually, so only consume complex carbs, so its not like I went from non-disciplined diet to full-on ketosis; I am used to disciplining myself with my food, but I genuinely felt depressed during my time on this diet.

  4. I just want to say that there has been reports of Ketoacidosis with a Ketogenic type diet, unlike what you have said. As per Up to Date inc. Which is the latest up to date research. People who folllow a very strict high protein low carb diet and lose large amounts of weight ( which we often see with these diets) that is they lose more than the recommended healthy 2lbs a week may be at risk for ketoacidosis. I have also discussed this diet with several of the dietitians I work with as many of my patients are asking about it and none of them recommend it! I must say that any diet that puts hot dogs as a “safe” food should really make people wonder…

    • This is simply not true. Ketosis and ketoacidosis are not the same.

      Ketosis, a natural and healthy phenomenon and common on a low-carb diet. Ketoacidosis is a symptom of uncontrolled diabetes and is completely different.

      I never said anything about hot dogs.

  5. No, you did not say anything baout hot dogs, however if you look at the “safe” foods for the diet list- hot dogs are on it.

    It is not the same thing- and ketoacidosis is very rare in non Type 1 diabetes, but it CAN happen. There have been documented cases of 3 people who have went into ketoacidosis from rapid weight loss on a high protein diet. Now it may have been related to the weight loss and not the diet itself, however it did happen.
    The diet was introduced as an epilepsy prevention and was often not followed due to the many side effects from it, I see you listed a few- however the list is much longer.
    Also I question any diet that requires supplements in order to prevent nutritional defiencies. A true healthy balanced diet should not cause a nutrional deficiency.

  6. As I stated here are the adverse effects i think people shoul dbe made aware of everything before they start on these ‘fad” diets and make sure they do proper research.
    ADVERSE EFFECTS — Dietary treatments for epilepsy are neither healthy nor free of potential side effects. A substantial proportion of patients who have a substantial benefit in seizure reduction on the diet discontinue the diet early because of intolerance [66,86].
    Parents and caregivers should be counseled as to the common, occasional, and rare adverse effects that can happen in the short-term when using dietary treatments, specifically the ketogenic diet. Fortunately, most adverse effects are predictable, often preventable, and only rarely in themselves lead to diet discontinuation [4].
    Relative common adverse effects include [4,66]:
     Gastrointestinal symptoms: diarrhea, constipation, nausea, vomiting, and exacerbation of gastroesophageal reflux are among the most common side effects, occurring in more than half of children on the ketogenic diet [4,8,63]. These are generally managed symptomatically with proton pump inhibitors, laxatives, and other treatments as needed.
     While abnormal lipid parameters are frequently seen, significant hypercholesterolemia and hypertriglyceridemia are less common [66,87,88]. Most levels improve spontaneously even without dietary or other intervention; and only a minority of patients require medication. Atherogenic consequences of the ketogenic diet, if any, are not known, but do not appear to happen in children followed years after the ketogenic diet has been discontinued.
     Abnormal laboratory parameters (hypoglycemia, hyperuricemia, hypoproteinemia, hypomagnesemia, hyponatremia, hepatitis, metabolic acidosis) are sometimes seen and should be monitored for (see ‘Maintenance’ above), but are usually minor [4,66]. Significant metabolic acidosis requiring treatment may be more common in children who are also taking topiramate or zonisamide [63].
     Most children on the ketogenic diet fall into lower height and weight percentiles [89-91]. Younger children on the diet for longer periods of time appear to be the most at risk. In one small series, height velocity was most affected in those with the most pronounced ketosis [92]. The higher protein content in the MCT diet does not appear to ameliorate this [93].
    Carnitine levels typically decline in the first months on the ketogenic diet; however, carnitine deficiency is not common (<20 percent) [66,94]. Levels typically stabilize or improve spontaneously without supplementation. We recommend supplementation for those who are symptomatic with fatigue and lethargy associated with low carnitine levels.
     Osteopenia, osteoporosis, and bone fractures are a concern for children maintained on the ketogenic diet, as they are for children on chronic AEDs [66,90,95,96]. Prophylactic supplementation with calcium and vitamin D is mandatory for all children on the diet, but sometimes fails to prevent continued bone loss. As yet, there is no well-defined role for the use of bone scanning and/or other treatments in this setting to reduce the risk of bone loss and fracture [4].
     Kidney stones may occur in as many as 7 percent of children [62,66]; if fluid intake is normal, the incidence is likely lower, and in one study was reduced to less than 1 percent with the addition of a potassium citrate supplement [61]. The risk for kidney stones is highest in those with baseline urologic abnormalities or a personal or family history of nephrolithiasis [62].
     Selenium deficiency has been found in up to 20 percent of children on the ketogenic diet and has produced an irreversible cardiomyopathy and sudden death in a few case reports of children on the ketogenic diet [97,98]. Cardiomyopathy and prolonged AT intervals have also been described in patients on the ketogenic diet who were not selenium deficient [99]. While selenium levels can be checked, this is not done routinely by all experts [4].
     Pancreatitis has been reported in a few children on the ketogenic diet [64,66,67]. Most cases, but not all, had another risk factor for pancreatitis, usually valproate administration.
     Seizure worsening has been anecdotally reported, similar to the potential with any anticonvulsant medication. The incidence is unknown.
     Iron-deficiency anemia has been observed in a small number of patients on the ketogenic diet [66].
     An increase in bruising and mild bleeding has been reported in patients on the ketogenic diet, suggesting an impact of the diet on platelet function [100]. This typically does not require any specific intervention.
    Once the diet is discontinued, most of these adverse effects resolve. In a follow-up study of 101 children who had discontinued the diet a median of six years prior, height, weight, cholesterol, and food preferences were all normal [101]. There was no increased risk of late reported cardiovascular disease, bone fractures, or kidney stones. Most patients were eating normal foods years later as well.

    Dr E. Kossoff
    Dr. D Nordlii
    Dr. J Wilderink
    Up to Date inc, 2012

  7. What is your point here? Are you saying that a ketogenic diet is unsafe?

    “No, you did not say anything baout hot dogs, however if you look at the “safe” foods for the diet list- hot dogs are on it.”

    You didn’t find that on my site.

    “Also I question any diet that requires supplements in order to prevent nutritional defiencies. A true healthy balanced diet should not cause a nutrional deficiency.”

    It does not require a supplement, although it is often recommended just in case.

    “As I stated here are the adverse effects i think people shoul dbe made aware of everything before they start on these ‘fad” diets and make sure they do proper research.”

    I’m not quite sure why you’re going on about this. I listed the potential adverse effects in the article, but generally ketogenic diets do have an outstanding safety profile.

    Please show me the study linking to harmful effects in humans, where the harmful effects outweigh the benefits of the diet (which are numerous).

    A diet that has been repeatedly shown in randomized controlled trials, published in peer-reviewed research journals, to be both safe, healthier and more effective than the standard of care (calorie restricted, low-fat diet) is NOT a fad diet.

  8. I am not saying it is unsafe, however it can be. People read about these diets, don’t do any research and then go overboard with them. They read a blog that says it is safe and that is it.

    I am going on because I know numerous people that are now following a “keto” diet, thinking it is a great diet and it has hot dogs on it! It just blows my mind that nobody seems to think “oh this is probably not the best” They just read that ketogenic diets are safe and so assume this it. They lose weight rapidly, more than 2 lbs a week- more than 5+ a week and think it is perfectly fine because “the diet is safe”.

    I am not saying you indicated hot dogs, I just had a patient of mine bring in the list to show me the diet he was following and hot dogs were listed as safe foods, as well as other highly processed meats. However banana’s were am absolute avoid.
    What I am saying is people don’t think most of the time- they just do, and so as a health care provider it urks me when people go on the internet and just follow whatever anyone says.

    As for the diet being research- it is thoroughly research in Epilepsy prevention- which is what it was first used for and continues to do so. Yes it is very effective in those regards, however even it effective it does not come without risk. I cannot link you the study because it is via Up to date which is a paid subscrition, you would not be able to view it without an account. All the studies that I saw were on Epilepsy prevention and its use/safety profile with that condition. I saw nothing on weight loss or other conditions. I work with dietitians on a daily basis and nobody has ever recommended this diet to any of my patients. I actually showed them the list and they felt it was a very unbalanced diet. Perhaps the list that I have been given is different then from what you use.
    I would be interested in the studies done regarding other health conditions, such as diabetes ( althought I am aware that diabetics require a low carbohydrate diet, it is the high fat that confuses me,) and weight loss as I did not come accorss any.

  9. Hello TL. Are you a doctor?

    Doing a simple search on will show you a ton of relevant results. A great search string is “low carb controlled trial.” It can be helpful sometimes to look at the data yourself before making a decision, instead of relying on a site like up-to-date that unfortunately isn’t as unbiased as you may think.

    Right now I’m working on a massive review article where I look at over 20 randomized controlled trials of low-carb, ketogenic diets vs. low-fat diets on obesity and cardiac risk factors. The diet is both safe and effective, that is a scientific fact that has been demonstrated repeatedly in randomized controlled trials.

    First of all, the fear of fat was unfounded. Saturated fat has no association with heart disease, anyone who keeps up with current research should know this. There is NO reason to be afraid of fat, it was a lie all along:

    Anyway, here is a bunch of randomized controlled trials on low-carb diets for obesity. Every single one of them shows that they are effective and have an outstanding effect on cardiac risk factors such as triglycerides and HDL. They do raise Total cholesterol a little bit, but mostly mediated by increased HDL. Their effects on LDL are usually very small and not statistically significant.

    Given that Triglycerides:HDL ratio may be the best predictor of heart disease, you could argue that low-carb diets reduce risk of heart disease (not to mention how incredibly effective substantial weight loss and diabetes remission will be for heart health).

    Also, low-carb diets, even those high in saturated fat, change LDL pattern from small, dense to large LDL (which is pretty much benign).

    I’m not surprised that the dietitians don’t know this, as they tend to not know much about the stuff that really matters and continue to promote an inferior, unhealthy, low-fat calorie restricted diet (even to diabetics, which is a crime against humanity in my opinion).

    Anyway, here is a list of randomized controlled trials. No cherry picking, all the studies are included. I sure do hope that you go through them and then show them to the dietitians at your workplace.

    I sure do hope that you will keep an open mind when going through these studies. Your patients lives may depend on it, literally, because low-carb diets are a potential cure for some of the biggest health problems in western nation but continue to be ignored by the nutrition and medical profession.

  10. Yes, I am GP, newly graduated of course :)
    I will definitely go through all of these trials myself as I really want to provide the best advice for my patients. I guess I may have sounded that I do not promote a low carbohydrate diet, which I do. I should have been more clear in that I promote a low-carb and yes low fat diet. I do not tell people to go for low fat salad dressing ect, I instead tell them to stay away from processed as much as possible and to try to stay away from the saturated fats. Not the ones who find naturally as in meats, but the ones you find in potato chips. I tell people to stay as fresh as possible and to avoid things that come in cans or boxes as they are more un-healthy. I advise all my patients to stay away from simple carbs and foods with high glycemic index, or to at least chose them the less often. My motto is usually that white refined sugars are bad. But I do encourage high fibers and whole grains as there a lot of benefits from them. This diet is especially true for my diabetic patients.

    Therefore maybe I am not far off from what you are saying. I don’t stress either extreme. I use to buy low fat everything, however I now wonder which one is worse the preservatives or the fat. I believe the preservatives. I think natural fats are not bad for us especially if people stay active, however not the processed high fat foods; such as bologna, fried foods, fast foods ect.

    As for your recent article review, I will be honest that it makes me nervous. I will definitely keep an open mind however it is hard when something questions everything you have been taught. I saw people putting down dietitians but you have to understand that if you start to believe all things things that were the total opposite then everything you’ve been taught then it starts to make you question everything and your entire profession. Also if we start practicing by “how we want ” and not evidence base we have a licensing body to answer. Therefore we need to make sure that whatever decision we are making has adequate research to back us up. Despite all that I want to deliver the best possible care to my patients and truly am a firm believer in life-style management vs pharmacotherpay as I believe our way of living can be our best ally or our worse enemy.

    Since you seem to be aware of nutritional up to date information I was wondering what your thoughts are on coconut oil. I started recommended it to my patients, that and olive oil, however I was told by several dietitians that the coconut oils are NOT heart healthy and I should not be recommending it. She proceeding by telling me that it took her 7 years ( she has a masters) to understand the science of nutrition and that it is not black and white and you really have to be aware of all its dimensions to better understand nutrition and that what we read on the internet is often false and miss-understood. I have since made a halt on it until I find more information as it is hard to argue with someone who has 7 years of nutritional training. She is gathering the evidence to send to me. What are your thoughts on it?

    Thank you very much for your information.

    • I haven’t done much research on it myself but I consider coconut oil to be a healthy, natural fat. Many populations around the world eat a large part of their calories as coconut fat and are in exceptional health.

      It is fairly unique in its fatty acid composition as it is composed mostly of medium chain triglycerides, which may have some health benefits.

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