What Are Ketosis Side Effects?

Dee Saale
Dee Saale

Not to be confused with ketoacidosis, a condition most often seen in diabetics, ketosis is a state in which the body has to use protein and reserves of fat because it doesn't have enough carbohydrates, often as a result of a low-carbohydrate diet. Remaining in a state of ketosis for prolonged periods of time due to dieting has been a controversial issue. While some believe it is harmful for the body to experience high levels of ketones for long duration, others disagree. Therefore, it is advised for those on low-carbohydrate diets to seek advice from their medical practitioner regarding their level of ketones in the body and general health.

One possible side effect is a headache.
One possible side effect is a headache.

Mild ketosis side effects may include bad breath and gas while more severe symptoms may include weakness, nausea, and dizziness. For some, ketosis side effects may remain mild. For example, since acetone is created inside the mouth during ketosis, many dieters experience bad breath. Brushing the teeth, mouth and tongue frequently may reduce this symptom. In addition, drinking more water and eating vegetables may also reduce the effect of ketosis.

Nausea can be a more severe side effect of ketosis.
Nausea can be a more severe side effect of ketosis.

Some people complain of other side effects — sudden dizziness, weakness, fatigue, and lethargy are quite common. In addition, most people complain of headaches, especially since their body is consuming significantly fewer calories when they are dieting. Although these side effects are not life threatening, they may cause people to make simple mistakes they would not normally make.

Sudden dizziness is a relatively common side effect of ketosis.
Sudden dizziness is a relatively common side effect of ketosis.

With any diet plan, it is always best to consult a medical provider. People with certain health concerns, such as high blood pressure and heart disease may be warned against high protein diets as well. If concerns arise regarding whether a person is going through more severe forms of ketosis, it is best to ask for medical advice.

When fatty acids are broken down in the body, ketones are formed, eventually leading to symptoms such as darker urine.
When fatty acids are broken down in the body, ketones are formed, eventually leading to symptoms such as darker urine.

Those suffering from diabetes, especially type I diabetes, are at risk of a more severe complication called ketoacidosis. However, in the case of type I diabetes, the individual experiences the condition because his or her body does not have sufficient insulin to use glucose, and the body relies on fat for energy. Ketoacidosis in diabetics is not to be taken lightly. If left untreated it may result in a diabetic coma. Regular urine tests to check for the level of ketones is an effective way for diabetics to prevent and apply for timely treatment in the case of dangerous ketone levels.

People with heart problems are often warned against high protein diets.
People with heart problems are often warned against high protein diets.
A low-carbohydrate diet can lead to ketosis breath.
A low-carbohydrate diet can lead to ketosis breath.
Dee Saale
Dee Saale

Dee is a freelance writer based in Colorado. She has a B.A. in English Literature, as well as a law degree. Dee is especially interested in topics relating to medicine, legal issues, and home improvement, which are her specialty when contributing to wiseGEEK.

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Discussion Comments


Some people think that ketosis leads to ketoacidosis, which is a completely distinct medical condition due to severe diabetes, and is deadly. If it were true then the millions of people on high fat low carb diets would be DEAD.

A diet to put a body into ketosis has been around for 100+ years, and is an outstanding treatment for childhood epilepsy. There is a vast body of current medical research on ketosis.


I suggest everyone to do their own research about ketosis. Take a look at the work of Volek and Phinney for example. There has been more than two decades of research into the ketogenic way of eating. Really interesting stuff.


Does anyone have any information about the new drink from Pruvit that put your body into ketosis in an hour? They claim to be safe and have no side effects.


I'm not totally on a low carb diet as I eat fruit and a few other items such as crackers, etc., along with a calorie restricted diet. I've lost 14 pounds in nine weeks and I've been a high carb eater all my life.

I began experiencing ketone symptoms and didn't know what was happening. I was dizzy, having frequent urination, shaky, panic attacks. Not good. Although your doctor can rule things out such as diabetes, etc., these symptoms can go unexplained and are usually treated with pills!

I suggest you see a nutritionist who is much more familiar with dietary issues. After trying the salt water drink experiment (1/2 tsp in a glass of water), I felt better in 20 minutes, which meant my potassium was low. Pay attention to your body and get the right help from a professional.


There are side effects for every single thing you ingest. The bottom line is that only you and your doctor know your body's scope and what it's allowing you to do. If you start to not feel better through a higher protein diet, then common sense will tell you to lay off it. Remember there's a happy medium for everything. Use your own good judgment.


Not quite accurate. Ketogenic diets are not high protein. Excess protein triggers gluconeogenesis, in which the liver produces glucose, hence kicking you out of ketosis.

I'm not saying ketosis is good for everybody, or that it has no side effects.. but high protein intake is certainly not encouraged. (Recommended protein intake is to be calculated according to body weight, for muscle maintenance, as in any other sensible diet).

On the other hand there are other possible (more serious) side effects worth considering, like decreased thyroid activity and temporary insulin resistance (if returning to a high-carb diet).


I've entered into ketosis recently and have experienced weight loss, increased energy levels, a significantly better mood, and only one downside of diarrhea on occasion, but not bad.

What this article doesn't mention is that various cultures very rarely consume carbohydrates, most notably the Inuit and Sami peoples. Their diet consists of mainly fat with the remainder of protein. They essentially live their whole lives in Ketosis without these 'dangerous' side effects. Additionally, most of these mood swings are likely the result of sugar withdrawals. Since sugar acts on the brain like most addicting drugs, it's not hard to imagine why a lack of sugar would produce withdrawal like symptoms.

This article reeks of this so called conventional wisdom that told us to avoid fats and eat more grains. So we did, and got fat and diabetes for our trouble.


Sorry but I've been on it for about two months now. The initial mood swings come from quitting sugar as it's an addictive substance. Once you get over the initial withdrawal symptoms, you actually feel more energized and alive than ever before. It's simple. Don't do this diet if you're diabetic. Otherwise, I recommend it to everyone.


Masai people eat high-protein no-carbs without any health issues. Same for Inuit. They are obviously in a ketosis state most of their life without any side effects. On the contrary, analysis revealed that they have excellent health and are immune to most diseases found in high-carb, average-protein, low-fat cultures.

Ketosis is a natural state of the body. Being high in carbs is not, the proof is that as soon as we eat them the body answers with production of insulin to avoid a high concentration of sugars in the blood. Still the main opinion is that carbohydrates are the preferred fuel for the human body. It's pathetic.


I put my self into ketosis to get rid or excess fluid round my joints as i have bad arthritis as its been the only effective way to do so. I tend to do it for a week to ten days. I have not as yet had any side effects such as others describe but usually feel very well on the diet! I've done this diet every years for 10 years now to good effect.

It does help you lose weight rapidly. I lose two pounds a day; that's why i can only do it for up to 10 days at the very most. But this said, it is extreme and i do it with my doctor's OK and i monitor my weight carefully throughout to not go to extremes. I want to keep my curves, not look like a stick insect. hope this helps!


@EarlyForest: People following low-carb diets tend to lose weight quickly in the beginning due to fluid loss. The carbohydrate stores in the body maintain the levels of fluid in your body - thus when one's carbohydrate intake is severely decreased, dehydration results.

Basically, it's essentially water weight that is being lost. In order for one to truly and effectively lose weight in the long run, you must burn more calories than you take in - simple as that.


So out of curiosity, how do diets that are so low in carbs work? If the side effects of ketosis are so dangerous, then how do people follow diets like that and lose weight?

I can definitely say that I have experienced some of these side effects, since I once went on an almost no-carb diet, but I cracked when the headaches started getting bad. Of course, I felt horribly guilty too, and was really moody, which I now know what an effect of the ketosis.

But back to the topic, how do people on low carb diets stay healthy and avoid going into long-term ketosis? Is there some trick to doing it that I just missed out on or what?


Excellent article. I will definitely be showing this to some of the girls who come into my clinic following those crazy diets.

It's things like this that make it so all-important to not try to do any serious dieting without talking to your doctor first.

So many people I see try to go on diets like this, end up with serious ketosis after a few weeks, and then go into crazy mood swings because of the ketosis, crack, and start binging and gain it all back.

Doing something like that is really just setting yourself up for failure, since the mood swings, irritability, headaches, etc, are just physical effects that you will experience -- it's not something that you can control by force of will or anything, no matter how strong your desire to lose weight is.

So if you really want to lose weight and do ketosis right, then talk to a doctor or nutritionist. There's no need to set yourself up for failure by going into extended ketosis and experiencing the "losing weight" side effects.


How funny -- I don't think that I had ever seen an article talking about the side effects of weight loss. Because that's basically what ketosis is, right, the process of weight loss?

This was really informative too, since it helped me to understand why exactly losing too much weight is dangerous. I mean, you always hear about how anorexia is dangerous and bad for the body, etc, but no one ever gives a scientific explanation for it.

But now I know! I will be sure to trot out my new knowledge about the side effects of ketosis at my next awkward lull in dinner table conversation.

Thanks wisegeek!

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