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Keto Flu and Coronavirus Symptoms: How to Tell Them Apart

By Fitoru | 24 March 2020
Woman with colds sitting while holding a white cup and blowing her nose

The keto diet is synonymous with keto flu. Browse any social media outlet and you’ll see active discussions on keto diet side effects, like headache, nausea, and fatigue. But the threat of coronavirus (COVID-19) has many would-be keto initiates pressing pause on their keto diets. 

With similar symptoms how can you be sure that the harmless keto flu isn’t actually the more serious and life-threatening COVID-19? We understand your trepidation, so in this article we’ll be breaking down the differences between keto flu and coronavirus symptoms and figuring out if the keto diet is even a good idea for your immune system right now. 

Science Acknowledges the Keto Flu

A new study (March 13, 2020) published in Frontiers in Nutrition confirmed what keto dieters have been saying all along: when you first start a keto diet, the body responds with flu-like symptoms.

  • Nausea
  • Fatigue
  • Headache
  • Dizziness and faintness
  • Irregular heartbeat
  • Low energy
  • Brain fog
  • Digestive issues like diarrhea
  • Dehydration

These side effects tend to linger for about a week or so and then taper off as your body becomes keto adapted (1).

What causes such a dramatic response?

Your body is used to burning carbohydrates for its energy needs, but when you go on a high-fat, low-carb keto diet, it’s forced to turn to fat for fuel, which is totally within its means but not what your body is used to. 

As fat is broken down into ketone bodies for energy, your body reacts not just with weight loss but with flu-like symptoms. These symptoms are normal and harmless, albeit annoying. 

There are ways, however, to reduce the length and severity of your keto-flu symptoms, like taking exogenous BHBs and MCT oil. It makes the transition quicker and easier.

Now, take a look at these symptoms again…headache, fatigue, dizziness, digestive upset, nausea, brain fog.

They all make the cut as coronavirus symptoms. So how do we know which is which?

How to Spot COVID-19

The coronavirus outbreak is perhaps the scariest and most widespread global pandemic since the 1918 Spanish flu. As we write this, there have been over 260,000 reported coronavirus cases, nearly 11,000 deaths, and 90,000 recoveries across the world. By the time you read this, those numbers will have dramatically increased.

As we all hunker down and practice social distancing and self-isolation in an effort to contain the virus and reduce the number of lives lost, we must stay alert to the symptoms of COVID-19:

  • Dry cough (no mucus)
  • Fever
  • Fatigue
  • Gastrointestinal issues like diarrhea
  • Nausea
  • Shortness of breath

Respiratory troubles signal the most severe symptoms that warrant a trip to the hospital.

  • Pain or tightness in the chest
  • Labored breathing
  • Confusion
  • Inability to get up
  • Bluish lips or face

The Keto Flu and Coronavirus Symptom Checker

The best way to figure out if your symptoms are keto or corona related is to pay attention to the symptoms that don’t overlap.

If you are suffering from flu-like symptoms along with carb cravings, dehydration, and quick weight loss, it’s likely the effects of your keto transition and you’re in the clear.

If, however, you are experiencing the distinguishing COVID-19 symptoms of fever, dry cough, and shortness of breath, it’s a safe bet that you can rule out the keto flu.

There’s also another contender that might be making you feel sick—the common cold. If you’re suffering from a runny nose or coughing up mucus, then you may just have a regular cold.

The Keto Flu and Coronavirus Symptom Checker

You Suspect Coronavirus. Now What?

That depends on the degree of your symptoms. Hospitals are flooded with critical cases and overwhelmed to capacity, so if you aren’t experiencing severe respiratory symptoms and are just battling mild flu symptoms, the Centers for Disease Control and Prevention (CDC) recommends calling your health care professional for a diagnosis and next steps. 

If you are having trouble breathing, chest pain, or a severe cough, please go to your nearest hospital for treatment. 

Is the Keto Diet Good for Your Immune System?

Now that you’ve got the symptoms sorted out and are confident you’ll be able to tell the difference between the keto diet and coronavirus, you may still be hesitating. With such severe carb restrictions, is the keto diet even good for your immune system?

Studies suggest that the keto diet does indeed strengthen your immune system, so you can give those hesitations the boot!

In 2019, Yale School of Medicine researchers set out to investigate the keto diet’s effect on inflammasomes. Inflammasomes help activate the immune system, but when they run rampant during infection, they can damage cells. Research suggests that the keto diet can inhibit the production of inflammasomes and in that way help protect your lungs. 

Findings showed that mice exposed to the influenza virus had a much better survival rate when fed a keto diet instead of a high-carb diet. They also had better lung function, which suggests the potential for the keto diet to stimulate the same lung-protective and anti-viral benefits in humans (2). 

Other studies show that, due to its anti-inflammatory nature, the keto diet helps change your gut’s microbiome for the better. And if you don’t know already, your gut houses approximately 70% of your immune cells!

The keto diet has such an effect on your gut health due to the ketone BHB, which decreases inflammation and blocks the production of inflammasomes. One more reason to supplement with exogenous BHB ketones to help your body ease into ketosis! 

Stay Safe and Be Well

If you’re thinking of embarking on a keto diet, we hope we’ve convinced you of its safety. There are so many benefits to this low-carb way of eating, from better brain function to fat and weight loss. And, of course, a boosted immune system.

As for protecting against viruses such as the coronavirus, there are additional ways to stay safe and boost your immune system. For immunity and safety tips, check out How to Boost Your Immune System Against Coronavirus.

And if you’re feeling a little stir crazy at home, then be sure to connect with us on social media or our YouTube channel, where we’re bringing you keto, nutrition, and fitness tips to keep you entertained and healthy!


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  • 15-25% Protein

  • 65-75% Fat

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