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Ketosis Symptoms: Learn to Identify and Evaluate All Signals

Published on: August 25, 2019

Ketosis Symptoms: Learn to Identify and Evaluate All Signals

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So you have started a ketogenic lifestyle. But the question is, how are you able to tell that you are in ketosis? In this article, we are going to help you identify common and uncommon ketosis symptoms that indicate your body has increased its ketone production. Keep reading.

How Do You Know When Your Body Is In Ketosis?

There are plenty of ways to tell that your body has achieved ketosis. You can pay attention to how your body feels, or you can get objective data by testing your blood, urine, or breath for the presence of ketones [1].

Even without taking objective tests, individuals who are in ketosis after following a ketogenic plan for at least two days feel a variety of unpleasant symptoms. These symptoms are collectively called keto flu [2].

We are going to discuss each symptom as we go along, but first, let’s find out if ketosis is beneficial for you.


Is it good for your body to be in ketosis?

Because nutritional ketosis is such a hot topic these days, a lot of people think that it is just a fad. But if you dive deeper into ketosis, you will realize that ketosis is a normal metabolic process. Therefore, it is desirable and happens as a result of fasting or eating a low-carbohydrate, high-fat diet [3].

Your body switches to a ketotic metabolic state if glucose is less available for fuel. Since your body lacks glucose to sustain its functions, it uses an alternate source of energy in the form of ketone bodies [4].

Being in nutritional ketosis is safe because in this case, your liver cells produce ketones only in small amounts. That said, the ketone bodies will not affect your blood pH [4].

As a matter of fact, ketosis has plenty of health benefits. These benefits are backed by scientific research and studies on human and animal subjects.

A 2019 study by the Ohio State University involving campus ROTC members revealed that subjects who were kept in nutritional ketosis for 12 weeks lost more than 5% of their body fat, almost 44 percent of their belly fat, and improved their insulin sensitivity (which predicts the risk of diabetes) [5].

Ketosis is also proven to suppress hunger, which makes it a useful tool for achieving weight loss [6].

In case you are not aware, nutritional ketosis has been used by modern physicians during the 1920s to treat childhood epilepsy [7]. Today, more studies show that nutritional ketosis helps with other neurological conditions such as Parkinson’s Disease, Alzheimer’s Disease, Amyotrophic Lateral Sclerosis, and Autism [8].


Ketosis Symptoms You Should Look Out For

While ketosis brings about positive changes in your health, a person who is still transitioning into ketosis will experience short-term symptoms that are mostly unpleasant. This transition period can be rough since the body is still adjusting to low glucose levels.

Common symptoms of ketosis

Being aware of these ketosis symptoms allows you to prepare for them and will hopefully condition your mind for success. Here’s what you can expect:

1. Bad breath (aka “keto breath”)

Keto breath is a tell-tale sign that your ketone levels have increased. Acetone, the least abundant ketone body, is responsible for bad breath as it is expelled via your lungs [9].

If you want to an objective way to confirm this, you can get a breath ketone meter [10]. Some individuals who follow a ketogenic lifestyle may measure their breath acetone and correlate it with their rate of fat loss [11].

2. Digestive issues

Some people get diarrhea while making their switch to keto, while some experience constipation.

Diarrhea happens because your body is still adjusting to the sudden increase of fat in your diet. It also occurs among those who take too many omega-6 fats. According to Virta Health, our digestive systems have limited tolerance for oils that are high in omega-6 fats [12].

On the other hand, constipation is the result of removing carbohydrate-rich foods that are also high in fiber from your diet. Whether you are experiencing diarrhea or constipation, be sure to drink more water.

3. Insomnia

If you find yourself unable to sleep properly while pursuing nutritional ketosis, know that you are not alone. While insomnia doesn’t last long, it can affect your mood and energy levels.


Not to mention, insufficient sleep increases your response to stress and decreases your performance [13].

All those nasty symptoms when switching to a ketogenic lifestyle can be responsible for insomnia. For instance, diarrhea can keep you up at night or wake you up in the middle of the night.

4. Decreased energy

Reducing carbohydrates in your diet for the first time can make you feel unusually weak. This is especially true if you used to follow a standard American diet that’s high in carbohydrates. People often describe themselves experiencing “brain fog” or “fatigue.”

Once your body gets used to tapping into fat for energy, you will have sustained energy. You will no longer experience energy dips throughout the day because your body can always tap into its stored fat any time.

5. Headaches

Headaches may be common, but they’re annoying.

Each gram of glycogen in your body is accompanied by 3 grams of water. Limiting your carbohydrate intake depletes your glycogen stores. Water molecules get excreted in the urine [14]. If you don’t drink enough water, you can get dehydrated. Dehydration causes headaches.

Withdrawing from sugar may also lead to headaches.

Measuring ketosis

The symptoms mentioned above will help you identify that you are in ketosis. However, if you want to detect the presence of ketones in your body, don’t miss out on these testing methods:

  • Blood testing - Testing your blood with a ketone meter is a surefire way to detect ketosis. It’s accurate since readings are not affected by your hydration status. Also, it measures beta-hydroxybutyrate which is a major energy-efficient ketone body.
  • Breath testing - We mentioned previously that this method measures acetone in the breath during ketosis. Breath testing is non-invasive, which is why one may prefer it instead of blood testing.
  • Urine testing - Over-the-counter ketone strips are used to detect the ketone body acetoacetate. After dipping the end of the ketone strip into a fresh urine sample, you’re going to notice a change in color. The darker the color, the higher your urine acetoacetate levels.


Uncommon symptoms of ketosis

Here are less common physical symptoms that manifest in some people. These symptoms often result from a micronutrient deficiency - vitamin, mineral, or both.

1. Hair loss

Hair loss is a less common sign that a person has entered ketosis. People who aim to achieve nutritional ketosis limit most carbohydrates in their diet and those carbohydrate-rich foods contain vitamins and minerals which are needed to produce healthy hair. These micronutrients, when lacking, are associated with hair loss [15]:

  • Riboflavin (vitamin B2)
  • Biotin (vitamin B7)
  • Folate (vitamin B9)
  • Vitamin C
  • Iron
  • Zinc

Replenishing these micronutrients through supplementation will mitigate hair loss.

2. Muscle cramps

Troublesome leg cramps can make people throw in the towel too early. In case you experience leg muscle cramps, know that they occur because of two possible reasons - dehydration and electrolyte imbalance.


Since transitioning to ketosis can deplete your glycogen stores and you lose water through your urine, you can get dehydrated - unless you ensure proper hydration. Increased urination also leads to sodium loss, which affects the balance of other electrolytes.

To resolve muscle cramps, take a magnesium supplement, add salt to your diet, and drink more water [16].

3. Heart palpitations

Does your heart pound suddenly or beat faster? We know that this symptom can be scary, and we’re here to tell you that it’s a side effect of ketosis.

Not everyone gets heart palpitations and those who do have them because they did not consume enough electrolytes upon reducing their carbohydrate intake.

Keep in mind that electrolytes such as sodium, potassium, calcium, and magnesium help conduct electrical impulses in your heart. An imbalance of these electrolytes will cause disturbances in your heart rhythm [17]. Most likely however is that dehydration will lead to low blood pressure. This results in palpitations as your heart beats faster to keep your blood pressure at normal levels.


When Do I Need to Consult a Doctor?

Ongoing doctor-supervised ketogenic lifestyle is highly advised. Not just any doctor, but a doctor who understands and knows how to implement a well-formulated ketogenic plan based on your current health and goals.

This is especially true if you have Type 2 Diabetes or hypertension and are taking medications. Your doctor will make adjustments to your medications since ketosis already lowers your blood glucose and blood pressure. Failure to adjust your medications might trigger hypoglycemia or hypotension [18].

If you experience the keto flu or any symptoms you are not sure about, don’t hesitate to call your doctor to ask for advice or get yourself evaluated. Also, test your blood ketone levels to make sure that they stay within the desired range of nutritional ketosis (0.5 and 2 mmol/L) [18].


While testing for the presence of ketones in your blood confirms ketosis, there are other symptoms that indicate ketosis as well. These symptoms are unpleasant and occur due to glycogen depletion, a change in your macros, and an electrolyte imbalance. If you follow a well-formulated ketogenic plan with medical supervision, you should have nothing to worry about.


  • Ketosis is beneficial, and has actually been used since the 1920s to treat childhood epilepsy.
  • Studies show that ketosis suppresses hunger, reduces body fat and helps with other neurological conditions.
  • Common ketosis symptoms include bad breath, diarrhea, constipation, insomnia, decreased energy and headaches.
  • Uncommon ketosis symptoms include hair loss, muscle cramps and heart palpitations.
  • Simple self caring measures like keeping yourself hydrated and ensuring a good salt intake can help stave off the majority of symptoms.


  1. Measuring ketosis on a ketogenic diet.
  2. Campos M. What is keto flu? 2018 October 28 -
  3. Phinney S, Volek J. Ketones and Nutritional Ketosis: Basic Terms and Concepts. 2018 April 18 -
  4. ... View all references

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