Keto Flu: What To Expect And When

The keto flu is a group of symptoms that some people experience when starting a ketogenic diet. The ketogenic diet is very low in carbohydrates, high in fat, and moderate in protein. The keto flu typically starts within the first few days of cutting back on carbs, and the symptoms can last for a few days to several weeks. The most common symptoms include headache, fatigue, nausea, dizziness, brain fog, gastrointestinal discomfort, decreased energy, feeling faint, and heartbeat alterations. The keto flu is not a cause for concern, and it is a sign that the body is adapting to ketosis. Staying hydrated and replenishing electrolytes are important ways to reduce the symptoms of the keto flu.

Keto flu symptoms

The keto flu is a collection of symptoms experienced by some people when they start a ketogenic diet. The symptoms are similar to those of the flu and are caused by the body adapting to a new diet consisting of very few carbohydrates.

The ketogenic diet is very low in carbohydrates, high in fat, and moderate in protein. This diet forces the body to burn ketones for energy instead of glucose. Ketones are byproducts of fat breakdown and become the main fuel source when following a ketogenic diet. This switch to burning fat for energy is called ketosis.

Symptoms of the keto flu can begin within the first few days of starting the diet and can range from mild to severe. For most people, the symptoms last a few days to a couple of weeks, but in extreme cases, they can last up to a month.

• Diarrhea or constipation
• Stomach or intestinal pain
• Nausea
• Headaches
• Dizziness
• Sugar cravings
• Muscle soreness or cramps
• Irritability
• Fatigue
• Trouble falling or staying asleep
• Poor focus and concentration
• Brain fog

The keto flu is temporary and can be managed by staying hydrated, replacing lost electrolytes, getting enough rest, ensuring adequate calorie and fat intake, and gradually reducing carbohydrate consumption.

How long does keto flu last?

The keto flu is a group of symptoms that some people experience when they start a ketogenic diet. The ketogenic diet is very low in carbohydrates, high in fat, and moderate in protein. The keto flu is a result of the body adapting to a new diet consisting of very few carbohydrates.

The symptoms of keto flu can begin within the first day or two of starting the diet, and they can range from mild to severe. The symptoms usually last a few days but can last several weeks in some cases. For an average person, the keto flu can last a week or less, but in extreme cases, it can last up to a month.

The keto flu is temporary and generally goes away within a week or two of beginning the keto diet. If your symptoms last longer than ten days, or if they are actively painful or debilitating, you may want to contact your doctor.

There are several ways to reduce the symptoms of keto flu:

• Staying hydrated is crucial as the keto diet can cause a rapid loss of water stores, increasing the risk of dehydration.
• Replenishing electrolytes is important as the keto diet can lead to electrolyte depletion.
• Getting enough rest and avoiding strenuous exercise during the initial phase of the keto diet is recommended.
• A slower transition to the keto diet by gradually reducing carbohydrate intake can help the body adjust more naturally.

What causes keto flu?

The keto flu is a collection of symptoms experienced by some people when they start a ketogenic diet. The symptoms can include headaches, fatigue, weakness, irritability, muscle cramps, insomnia, nausea, and constipation. The keto flu is caused by the body adapting to a new diet consisting of very few carbohydrates.

There are several factors that can contribute to keto flu:

Dehydration and Electrolyte Loss

The keto diet's high-fat, low-carb protocol causes a drop in insulin levels. Insulin is a crucial hormone for blood sugar regulation and fat storage. This low insulin level triggers ketosis, but it also causes water loss and electrolyte depletion in the early days of keto adaptation. This can lead to muscle cramps, headaches, and fatigue.

Increased B Vitamin Requirements

Using fat as a fuel source requires different metabolic pathways than burning sugar. Efficient ketosis relies on good levels of B vitamins. Switching to keto can cause a dip in B vitamin levels, resulting in keto flu symptoms like body aches, low energy, and sugar cravings.

Carbohydrate Withdrawal

Starting keto can lead to carb withdrawal, making keto flu symptoms worse. When the body is used to burning sugar for energy, the brain is primed to seek out more carbs when blood sugar is low. The transition to a low-carb diet can cause intense sugar cravings, irritability, and lightheadedness.

Sodium Deficiency

Low-carb diets minimize insulin, which plays a role in telling the kidneys to retain sodium. This can lead to sodium deficiency, as the body excretes too much sodium through urine. Sodium deficiency can cause symptoms such as headaches, muscle cramps, weakness, brain fog, insomnia, and more, which overlap significantly with keto flu symptoms.

Reduced Brain Fuel

When reducing carb intake, the body has to use fat and ketones for fuel instead of carbs. This means the brain also has to use fat as fuel, and some people can take a few days or weeks to fully adjust, leading to cognition-related keto flu symptoms such as headaches, brain fog, low energy, and fatigue.

How to get rid of keto flu

The keto flu is a collection of symptoms experienced by some people when they first start a ketogenic diet. Symptoms can vary from mild to severe and include fatigue, muscle cramps, headaches, nausea, constipation, and cravings. The good news is that the keto flu is temporary and usually goes away within a week or two. Here are some ways to get rid of the keto flu:

• Stay hydrated: Drink plenty of water to prevent dehydration, which can worsen keto flu symptoms.
• Replace electrolytes: Include more salt in your food or drink sports drinks that are high in electrolytes. Electrolytes can also be replaced by consuming bone broth, which is keto-approved and naturally high in electrolytes.
• Eat more fat and calories: Ensure you are consuming enough fat and calories to curb cravings and hunger. Eat nutrient-dense, high-quality foods that support healthy vitamin and mineral levels.
• Get enough sleep: Create a bedtime routine to help overcome sleep-related symptoms. Reduce caffeine intake and cut out ambient light from electronic devices in the bedroom.
• Adjust your exercise routine: Avoid high-intensity exercises until your body is fully keto-adapted. Opt for lighter forms of exercise such as walking, yoga, or swimming.
• Consider a slower transition: If the keto flu makes it difficult to stick to the keto diet, you can ease into it by gradually reducing your carbohydrate intake over a few days or weeks.

Who is likely to get keto flu?

The keto flu is a collection of symptoms experienced by some people when they first start the keto diet. The symptoms can feel similar to the flu and are caused by the body adapting to a new diet consisting of very few carbohydrates.

The keto flu is likely to affect people who:

• Are experiencing dehydration and electrolyte loss. As your body transitions to a high-fat, low-carb protocol, your insulin levels drop, causing water loss and electrolyte depletion in the early days of keto-adaptation.
• Have increased B vitamin requirements. Using fat as a fuel source requires different metabolic pathways than burning sugar. Efficient ketosis relies on good levels of B vitamins. Switching to keto can cause a dip in your B vitamin levels, resulting in typical keto flu symptoms like body aches, low energy, and sugar cravings.
• Are going through carbohydrate withdrawal. Starting keto can cause carb withdrawal and may make your keto flu symptoms worse. When burning sugar for energy, your brain is primed to seek out more carbs whenever blood sugar is low. The transition to a low-carb diet can cause intense sugar cravings, irritability, and lightheadedness.
• Are experiencing a drastic reduction in carbohydrates. This can come as a shock to the body and may cause withdrawal-like symptoms, similar to those experienced when weaning off an addictive substance like caffeine.
• Are consuming a lot of refined carbohydrates. Those who typically consume lots of carbs, especially refined carbs like pasta, sugary cereal, and soda, may have a more difficult time when beginning the ketogenic diet.

The keto flu is not likely to be experienced by people who are naturally "metabolically flexible", meaning they can shift metabolic states easily without experiencing health symptoms.

Frequently asked questions