3 Easy Fixes for Keto Flu and Low-Carb Side Effects

Learn how to fix your keto and low-carb side effects to feel better than ever

Alright, high five! You’ve started a high-fat, low-carb lifestyle or incorporated intermittent fasting into your wellness routine, you’re well on your way to enjoying some major health benefits like weight loss, reduced blood sugar and insulin levels, and better cholesterol levels.[1, 2, 3]

But after the first few days of your new routine, you might feel a bit… icky. Maybe you have a dull headache, some leg cramps, or constipation, and you think you might’ve caught a cold. 

If that sounds like you, you’re probably experiencing what has come to be known as the keto flu—a temporary, non-contagious stage of symptoms that occurs as your body adjusts to burning fat for fuel. 

And I’ve got some good news for you. 

Keto flu symptoms are totally manageable, temporary, and experiencing them means you’re closer than ever to achieving your goal of being a fat-burning, disease-preventing, metabolically flexible machine. 

Below, we’ll cover some quick fixes to help lessen your side-effects and get you over the initial hump so you can get back to doing what you love and march onward to keto success. Trust me, when your side effects subside, you’ll feel better than ever.

What is keto flu?

Let’s get into the nitty-gritty, shall we? 

Keto flu symptoms occur as your body switches from burning glucose for energy to using stored fat for energy. I’d bargain it’s been a while (or forever) since your body switched from using glucose to fat. If so, you’re a little metabolically rusty. 

Switching from a high-carb, low-fat to a high-fat, low-carb diet takes some adjusting. Your new low-carb diet lowers the insulin levels in your bloodstream.[4] Eventually, low insulin levels signal to your liver that it’s time to produce ketones as an energy source. This state is called ketosis.[5]  

Initially, your body will react to low insulin levels by excreting more water and sodium. If you’ve felt like you have to urinate frequently in your first low-carb, high-fat week or so, this is why. 

Rapid water and sodium loss are usually responsible for your initial weight-loss results—hooray! But water and sodium loss can leave you feeling tired, crampy, and downright cranky.

What are common keto flu symptoms?

Not everyone will experience keto flu symptoms when they begin a high-fat, low-carb diet. 

Symptoms are highly individualized and depend on genetic, epigenetic, environmental, and developmental factors. So some folks may feel like they’re in tip-top shape during the few low-carb days, while other folks might feel groggy and flu-ish. 

If you’re experiencing any of the following symptoms during your first week of keto, you’re likely experiencing keto flu:[6]

  • Irritability 
  • Fatigue
  • Headache
  • Brain fog or difficulty concentrating 
  • Intermittent dizziness
  • Sugar cravings
  • Nausea
  • Constipation
  • Muscle cramps or soreness
  • Weakness

These symptoms are no fun. But the good news is that they can usually be remedied or avoided altogether with just three simple tips.

When does keto flu hit?

If you experience any keto flu symptoms, they’ll usually appear during your first keto week.  Most people report symptoms between days 3 and 5 when the body is going through significant changes and adapting to its new low-carb environment.[7]

Whether you have keto flu symptoms for one day or five, the symptoms will subside and you’ll be left feeling shiny new and metabolically rejuvenated

How to cure your case of the keto flu

Don’t forget that your body is quite literally designed to use its fat stores for energy, and your initial keto flu symptoms will usually disappear all by themselves in a few days.

But if you’ve got a bad case or don’t want to wait it out, there are a few simple things you can do to ensure you make a speedy recovery. These tips to remedy keto flu symptoms are easy-peasy and highly effective.

Keto Flu Tip #1: Drink lots of water and increase your salt intake.

The number-one tip I tell my patients when they start a low-carb, high-fat lifestyle is to drink lots of water and increase their salt intake. *But not just any salt will do. I recommend Redmond or Himalayan Sea Salt, though any non-iodized sea salt or Celtic salt will do. The key is to avoid Morton’s variety, since it’s highly processed and won’t work as well to relieve your symptoms. 

Water and salt loss are the culprits for most keto flu symptoms.[8] And even if you don’t have keto flu symptoms, drinking extra water is a wise choice since it’ll help prevent you from experiencing symptoms in the first place. 

If you feel a headache coming or feel slightly nauseous, try drinking a full glass of water with half a teaspoon of salt in it. Feel free to warm the water to dissolve the salt; then drink it at room temperature. 

If you’re craving something a bit more robust, warm some bone broth or chicken stock. Add salted butter or a few pinches of salt and sip away. Your symptoms may subside in as little as 30 minutes.

Keto Flu Tip #2: Eat more fat.

If you increase your water and salt intake and you still don’t feel great, eat more healthy fats. At first, this might be a hard mindset shift since we’ve been berated with misinformation about fats for decades. But decreasing carb intake without upping healthy fat intake is a sure way to feel icky. 

If you feel tired and hungry, add more butter, ghee, lard, or healthy oils to your meals. Healthy fats will provide your body with the fuel it needs to run efficiently. Not to mention once you’re fat-adapted, healthy fats will keep you satiated so you’ll be able to go for several hours without having to eat while still having lots of energy. 

Stick with olive oil, avocado oil, and coconut oils and be sure to avoid plant oils like vegetable and canola oil. Eat an avocado or a handful of nuts for an extra healthy fat boost.

Keto Flu Tip #3: Stick to light, gentle exercise.

Starting the keto lifestyle is a big deal. And more often than not, folks are invigorated by their healthy choices and they’re ready to jump feet-first into exercising to get fit. But adding too much physical exertion right away can exacerbate or worsen your keto flu symptoms. 

In your first week, stick to light, gentle exercises like walking, stretching, or yoga. These activities will keep you active without taxing your body while it adjusts to its new fuel source. They’ll also also keep your mind attuned and calm which can go a long way to achieving whole-body harmony. 

As your body adapts to its new fuel source and becomes efficient at burning fat, you’ll be able to up your physical activity, do more, and challenge yourself.

Set yourself up for high-fat, low-carb success

When you implement these three tips, your keto flu symptoms will subside quickly and you’ll be in full-blown keto bliss in no time. 

Here’s a quick recap so you know exactly how to remedy your keto flu symptoms:

  1. Drink more water and increase your sale intake
  2. Eat more healthy fats
  3. Take it easy! Stick to light activity for your first week. 

Remember, your body is designed to be metabolically flexible. It is very capable of using your stored body fat as fuel. And when you get over this initial hump, you’ll be primed to live a life of high-fat, low-carb benefits. 

To talk with a metabolically trained physician, click here. These doctors are metabolic experts and can’t wait to help you achieve health and happiness by tending to your metabolic health. 

To learn how intermittent fasting can be a mega health-boosting addition to your low-carb, high-fat lifestyle, click here


  1. https://www.nejm.org/doi/full/10.1056/NEJMoa022637
  2. https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/1743-7075-2-34
  3. https://pubmed.ncbi.nlm.nih.gov/10584043/
  4. https://pubmed.ncbi.nlm.nih.gov/17684196/
  5. https://pubmed.ncbi.nlm.nih.gov/2656155/
  6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2633336/
  7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7082414/
  8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2633336/