keto flu and feeling ill

What is Keto Flu?

The ketogenic diet is a high-fat diet that forces the body to use ketones instead of glucose as the main source of energy.

When the body alters its energy source, it initially responds with flu-like symptoms. Think of it as a detox.


It’s difficult to find who coined the term “keto flu” but it is certainly fitting. Ugh!

While it’s not a genuinely diagnosed medical condition, the term, keto flu, represents anecdotal evidence of symptoms that are similar to the flu virus.

Keto Flu Symptoms

The keto flu occurs when some people first start on the keto diet. As your body enters ketosis, symptoms similar to the flu may appear within the first week.

Your body is adjusting to new nutrition that is high in fat with moderate protein, and restricted carbohydrates.

The reduction in your carb intake forces your body to burn ketones instead of glucose. Symptoms can include fatigue, muscle cramps, nausea, sugar cravings, headaches, constipation, insomnia, and bad breath.

Some people don’t experience any of these conditions while others may have one or more of them. The important thing to know is that this is a temporary phase.

Keto flu usually lasts roughly one week but some people experience it for a slightly longer period.

Although these side effects may tempt you to throw in the towel, remember “no pain, no gain” or in this case “no pain, no weight loss.”

What Causes The Keto Flu?

The medical jury is out when it comes to why some individuals experience keto flu to a less or greater extent. If you have been following the Standard American Diet, carbohydrates have been your main source of fuel.

The Keto Diet replaces carbs with fat as your energy source and adjusting to that new fuel may be the reason.

However, the keto diet also means that you are removing processed foods from meals and snacks so keto flu may be a reaction to simply cleansing your system.

Since your liver is burning fat and making ketones during ketosis, your insulin will be lowered.

Low insulin causes your body to eliminate more water, sodium, and potassium through both exhalation and urination.

Remedies and Treatments for Keto Flu

Many keto flu symptoms are caused by reduced sodium and dehydration. Adding extra salt to your diet and increasing electrolytes make it simpler for your body to get accustomed to ketosis.

Increase Fluid Intake

Increasing your salt and water intake can help reduce the severity of many keto flu symptoms, particularly if you’re suffering from dehydration or loss of salt.

Dissolve a 1/2 teaspoon of salt in a glass of water if you have a headache, tiredness, nausea, dizziness, or other symptoms during the first few weeks of your keto diet. This can reduce your symptoms quickly.

pink salt

You can repeat this process twice a day or more if required.

Alternatively, you may choose chicken stock, bouillon, bone broth, beef stock, or consommé – and add a spoonful of salted butter if desired. 

If you’re using low-sodium broth, add a touch of salt You may also drink tea or coffee in moderation.

water hydration

It’s also crucial to maintain an adequate water intake. The greater your size, the more water you’ll lose in the early phases of keto, and the more water you’ll need to replenish.

Use your body weight to determine your daily water intake. Figure out 75% of your weight and drink the equivalent amount in ounces of water.

Getting enough water, salt, and other electrolytes like magnesium and potassium, as well as fiber, might help with constipation.

Eat More Fat

It may seem counterintuitive due to ingrained bias and media coverage but eating more fat is a solution to fatigue, hunger, and irritability.

When you embark on the keto lifestyle, be sure to increase your intake of fat until your body adjusts to using ketones for the majority of its energy needs.

Since you are restricting carbs on keto, you need to replace them with enough fat or you’re going to feel like you’re starving.

A proper keto diet means that you will have sufficient energy, and enable you to sustain longer intervals between meals without feeling hunger pangs.

Once you’ve hit your stride, pay attention to how much fat you need to feel full. We have fabulous recipes to point you in the right direction.

Ease Into Your Transition

Try your best to make it through the keto flu using the remedies we’ve mentioned. It’s a temporary condition and you can make it to the other side where you’ll feel and see the benefits.

If you decide that your symptoms are too overwhelming, perhaps you need to transition to ketosis in a slightly slower fashion. Try eating up to 50 grams of carbs per day and slowly decrease the daily amount.

The early results may not be as dramatic but you can still get to ketosis – your journey may be slightly protracted but you can get to the keto destination with perseverance and commitment.

Eventually, you can reach a goal of fewer than 20 grams of carbs daily.

Keto diet concept. Food diagram showing percentage of fats, carbs and protein. Low-carb nutrition. Ketogenic diet graphic. Isolated vector illustration in cartoon style

Slow Down on Workouts

Many individuals notice that their energy and stamina improve while following a ketogenic diet, but attempting to do too much in the early phases may exacerbate keto flu symptoms.

Dr. Steve Phinney, an expert on the ketogenic diet, has conducted research in athletes and obese individuals, which revealed that physical performance deteriorates during the first week of very low-carb dieting.

Be Gentle with yourself

The good news is that his study also reveals that, on average, performance rebounds in 4 to 6 weeks.

Consequently, light exercise in the early phase of ketosis is recommended rather than over-exertion. Give your body time to adjust and gradually increase intensity.

Eat Enough Food

In the early stages of your transition to keto, individuals often get anxious about their food intake. Some symptoms of the keto flu make people less inclined to eat.

Other individuals are concerned that they’re eating too much to achieve weight loss.

Concentrate on consuming keto foods that are satiating. Don’t focus on calorie intake. Eventually, when you’ve achieved nutritional ketosis, your desire for food will naturally subside.

Eat slowly and be aware of the signs that you are full.

When to see a doctor

The keto flu is a mild sickness that most people experience for a few days to a week after beginning the ketogenic diet. However, if you are experiencing prolonged or more severe symptoms, consult your physician.

A medical opinion can diagnose whether other conditions may be the underlying causes of your discomfort.

Navigate The Early Bumps On The Road to Keto Health

As you start your journey, you may encounter the keto flu. Knowing that temporary, unpleasant side effects may lie in your path is the first helps you prepare for your new lifestyle.

Taking measures to reduce the symptoms of keto flu will help. Keep yourself on track to witness the health benefits of ketosis and succeed in your weight loss goals.

Remember, we can offer a helping hand whenever you need it so don’t hesitate to get in touch by emailing us at

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