Keto · Recovery    

Keto Flu: Ultimate Guide to Symptoms, Causes & How to Beat It


If you’re doing a ketogenic diet, you’ve probably heard of the dreaded keto flu — that cluster of headaches, fatigue, brain fog, and cramps that many people get in the first few days. These symptoms are usually temporary, but they’re often caused by electrolyte imbalances as your body adapts. This guide will explain why keto flu happens, what symptoms to watch for, and practical steps to feel better fast.

In this article, you will learn:

What is the Keto Flu?

When you suddenly and completely remove most carbohydrates and your body is changing from using glucose as fuel to breaking down fat for energy, your body is going through a huge metabolic shift. This can result in a number of symptoms 

Why the Keto Flu Happens

As your body adapts to using fat as fuel, there is a drop in insulin that causes your kidneys to work overtime. Although short-term, this diuretic effect can cause dehydration and an electrolyte imbalance. Many keto flu symptoms are the result of that alone.

Low energy and brain fog may be the result of draining glycogen stores, and as you switch from eating starchy vegetables and grains to a very high-fat, low fiber diet, you’ll likely have some digestive issues.

Not to worry. Once you’re in ketosis, these symptoms will dissipate and eventually will be replaced by the benefits of a keto diet. 

Symptoms of the Keto Flu

You may only feel one or two of these, or you may feel them all. Symptoms may last for a few days or up to two weeks. Everybody is different.

  • Brain fog
  • Nausea
  • Headaches
  • Constipation
  • Cravings
  • Dizziness
  • Irritability
  • Cramping
  • Muscle soreness
  • Insomnia

Ways to Cure the Keto Flu

1. Keep Moving

High-intensity interval training (HIIT) is best, but if you’re not feeling great, even light movement will give you more energy, help with muscle soreness, and boost your mood.

2. Try Intermittent Fasting

Fasting for 13-16 hours every day will help your body drain glycogen stores and up ketone production faster. The quicker you’re in ketosis, the more likely the keto flu will subside.

3. Take a Mineral Supplement

Your body will excrete minerals like sodium, potassium, magnesium, and calcium more quickly during the first week or so of the keto diet. Replenish your minerals with a high-quality bone broth supplement like Natural Force Organic Bone Broth Protein (the natural and turmeric flavors only). Or, try a sugar-free electrolyte supplement.

4. Stay Hydrated

You may be more dehydrated during the first days and weeks of a keto diet. Increase your water intake to prevent dehydration and all the symptoms that come with it.

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5. Eat More Fat

No, you probably aren’t eating enough fat. When in doubt, add more MCT oil, Creamy MCT oil, grass-fed butter, olive oil, and avocados to your diet. More fat will fill you up quickly and encourage your body to kick into ketosis faster.

6. Increase Your Fiber Intake

Many people on the keto diet have a woefully low fiber intake. But there are plenty of low-carb vegetables that contain fiber. If you’re suffering from cramping or constipation, try increasing your intake of low-carb vegetables like greens, cauliflower, broccoli, and avocado.

7. Play With Your Carbohydrate Intake

Everyone has wildly different needs when it comes to macro ratios. If you’re down to 15-20 grams of carbs per day and you can’t pull yourself out of bed, try adding another 20-30 grams. Your needs will vary according to your age, sex, health issues, and activity level. Play with it until you have a bit more energy.

8. Get Plenty of Rest

Your sleep may suffer during the first few weeks of the keto diet, so plan for some extra time to rest. Nap if you can, or plan on going to bed a couple of hours early to make up for fitful sleep.   If you’re suffering a few (or all) of these symptoms, remember: it’s normal! And don’t give up.

Try the tips above to speed your transition into keto so you can start to feel the benefits quickly!



Frequently Asked Questions

How long does keto flu last? For most people, keto flu symptoms last 3–7 days as the body adapts, but this can vary depending on how well you manage hydration and electrolytes. 
Can I completely avoid keto flu? Not always, but replenishing sodium, potassium, and magnesium aggressively — especially in the first few days — greatly reduces the risk and severity. 
What happens if I ignore keto flu symptoms? Persistent electrolyte imbalances can lead to muscle cramps, heart palpitations, or low blood pressure. 
Are supplements necessary for preventing keto flu? Not always — you can get electrolytes from food (e.g., bone broth for sodium, leafy greens for potassium), but many people benefit from supplementing, especially in early keto.
Should I consult a doctor if I get keto flu? Yes — especially if you have medical conditions, take medicine, or experience severe symptoms like rapid heart rate or dizzy spells.


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