GET $10, GIVE $10
Give your friends $10 off on their first order of $50+ and get $10 in points for each successful referral.
Get $10 Now


Ketosis Side Effects: Most Common and How To Manage Them

Published on: August 24, 2019

Ketosis Side Effects: Most Common and How To Manage Them

Previous Article: What are Optimal Ketosis and Ketone Levels?

Main Page (Index): Ketosis: The Complete Guide

Next Article: Ketosis Symptoms: Learn to Identify and Evaluate All Signals

Nutritional ketosis as a result of following a well-formulated ketogenic diet has many documented benefits ranging from weight loss to a lowered risk of developing various diseases. While we know these benefits, it’s also helpful to talk about ketosis side effects - both common and unexpected.

Being knowledgeable of these side effects helps you prepare and ease into ketosis with less stress. Here are the things you ought to expect and what you must do to prevent or alleviate the side effects.


3 Major Causes of Ketosis Side Effects

Before we dive into the specific side effects of nutritional ketosis, we’re going to explore exactly why they take place.

1. Water loss and electrolyte imbalance

One of the things that you’ll notice as your body adapts to ketosis is that you urinate more often.

Here’s the explanation: Depriving your body of dietary carbohydrates will result in the depletion of your glycogen stores. In case you’re not aware, every gram of glycogen is also stored with at least 3 grams of water. As muscle glycogen breaks down, the water molecules are excreted in the urine [1].

Your kidneys don’t just eliminate excess water, they also eliminate sodium and other electrolytes such as potassium and calcium.


2. Low blood glucose levels

Research shows that dietary carbohydrate restriction has the most significant effect on lowering blood glucose levels [2].

Short-term episodes of low blood sugar or hypoglycemia occur during your first attempt on keto. This usually happens if you have been used to eating large amounts of carbohydrates.

Your usual carb consumption triggers a certain amount of insulin to be released, which explains why drastically reducing your carbs will most likely lead to hypoglycemia. Your pancreas which releases insulin has to learn to secrete less in the absence of carbs.


3. A reduction in fiber-rich foods

Until your digestive system adapts to ketosis, you will experience symptoms such as constipation and diarrhea. These symptoms are a result of cutting most fiber-rich foods from your diet.

As you may already know, good sources of fiber include whole grains, fruits, and vegetables. However, a lot of these fiber sources also happen to be high in carbohydrates [3]. For instance, vegetables that grow below the ground, i.e. root vegetables [4].


10 Common Side Effects of Ketosis

One thing you should remember about ketosis side effects, collectively known as “keto flu,” is that they do not last very long.

Keto-adaptation varies from person to person. It can take weeks for some individuals to become keto-adapted while it can take months for others [5]. Within that period, you might experience any or all of these symptoms:

  1. Increased sugar cravings - As you withdraw from carbohydrates, you are expected to have intense cravings for sweet, high-carb foods. You might also feel irritable and thirsty [6].
  2. Fatigue - Electrolyte imbalances due to increased urination leads to short-term fatigue. Fatigue is one of the reasons why many people quit at the start of their keto journey.
  3. Headaches - Dehydration and electrolyte imbalances induce headaches. Replacing lost fluids and electrolytes prevent and reduce headaches [7].
  4. Digestive issues - Inadequate fluid intake causes constipation, while a change in macronutrient intake causes diarrhea.
  5. Muscle cramps - Cramps result from an imbalance of minerals such as magnesium, sodium, and potassium [8].
  6. Bad breath - When your ketone levels increase, acetone, a ketone body, appears in your exhaled breath. “Acetone breath” is described as a sweet odor, and it can be a useful indicator of ketosis [9, 10].
  7. Frequent urination - As mentioned earlier, your body burns through your stored glycogen. This manifests as increased urination since glycogen is also stored with water.
  8. Heart palpitations - You may experience an increase in your heart rate as a result of dehydration or low sodium levels.
  9. Interrupted sleep or insomnia - While nutritional ketosis has been shown to improve sleep quality [11], you may have short-term insomnia due to an electrolyte imbalance during keto-transition.
  10. Dizziness and lightheadedness - Electrolyte imbalances involving sodium, potassium, calcium, and magnesium can also result in dizziness and lightheadedness [12].


Avoiding & Managing the Side Effects of Ketosis

For this section, we’re going to introduce practical steps you can take to transition into ketosis easily.

1. Keep yourself hydrated

Since dehydration can happen on keto, as you are urinating more often, staying hydrated prevents this from happening. Make sure to increase your water intake.

Doing this will not only help prevent a loss in electrolytes, especially when you’re sweating or experiencing diarrhea, but it will also relieve constipation [13, 14].

2. Replenish your electrolytes

Between taking supplements to replace lost electrolytes and consuming these micronutrients through your diet, micronutrients from the diet are best. The reason is that micronutrients in whole foods are better absorbed by your body [15].

Pay attention to electrolytes such as sodium, potassium, calcium, and magnesium.

3. Get enough fat in your diet

Intense food cravings can be reduced by making sure that you eat enough fat.

Study shows that medium chain triglycerides (MCT) improve satiety. Also, a longer fatty acid chain length stimulates the secretion of Cholecystokinin (CCK). CCK is known to be involved in feeding regulation [16, 17].

4. Don’t go for long hours without food

You can experience hypoglycemic reactions until your body gets used to running on fat for fuel. Waiting for hours until your next meal can be difficult.

At the start of your ketogenic journey, you might need to eat more frequently. However, choose foods that will not kick you out of ketosis. Have keto-friendly snacks on hand such as hard-boiled eggs, low-carb beef jerky, and full-fat cheese.


When Should You See a Doctor?

Nutritional ketosis should not result in unwanted side effects provided that it’s well-formulated and that you’ve sought medical advice. Ongoing expert medical supervision is crucial, especially if you have a chronic condition such as Type 2 Diabetes and hypertension or are breastfeeding [18].

Uncommon side effects that need immediate medical attention

1. Seizures and abnormal heart rhythms

Electrolytes maintain nerve and muscle function. Chronically low levels of electrolytes result in serious problems such as abnormal heart rhythms and seizures. Again, electrolyte imbalances can be prevented by making sure that you meet your electrolyte needs in your high-fat, low-carb diet [19, 20].

2. Ketoacidosis

There are rare cases where non-type 1 diabetic individuals who have tried ketogenic diets have been admitted to the hospital due to ketoacidosis. However, medical assessment revealed that these individuals are breastfeeding and have completely eliminated carbohydrates from their diet [21, 22].


With this guide, you should be able to keto-adapt in a less stressful and more manageable way. All the side effects of getting into nutritional ketosis are a result of your body trying to adapt to a new fuel source - fat. Be sure to stay hydrated, replenish your electrolytes, increase your dietary fat intake, and avoid hypoglycemic reactions.


  • Shifting your metabolism so that your body runs on fat will result in uncomfortable symptoms. People often refer to these symptoms as the keto flu.
  • Ketosis side effects do not last long. It may take weeks to months for a person to become keto-adapted.
  • Common side effects include increased sugar cravings, headaches, muscle cramps, digestive issues, and insomnia.
  • In very rare occasions, ketoacidosis, seizures, and abnormal heart rhythms happen. Usually, these occur because an individual does not practice a ketogenic lifestyle in a healthy and well-formulated manner.


  1. Murray B, Rosenbloom C. Fundamentals of glycogen metabolism for coaches and athletes. 2018 February 10 -
  2. Feinman RD et al. Dietary carbohydrate restriction as the first approach in diabetes management: Critical review and evidence base. 2015 January -
  3. ... View all references

Join Over 200,000 Fans

Sign up for the Kiss My Keto mailing list to get free keto resources, recipes, and strategies from the largest keto brand in the world.