The Keto Flu – What It Is and How to Beat It

Many people starting the ketogenic diet experience a short-term side effect commonly known as the “keto flu.” While the name sounds intimidating, it’s not an actual illness — rather, it’s the body’s response to switching fuel sources from carbohydrates to fat.

What Causes the Keto Flu?

When carb intake drops drastically, insulin levels fall and the body begins flushing out water and electrolytes. This shift can create temporary imbalances, leading to symptoms such as fatigue, headaches, nausea, irritability, and muscle cramps.

How Long Does It Last?

The keto flu usually appears within the first 2–5 days of starting keto and can last up to a week. For most, it’s a sign that the body is transitioning into ketosis — a positive milestone toward fat adaptation.

Tips to Overcome Keto Flu:

• Stay Hydrated: Drink plenty of water to counteract increased fluid loss.

• Replenish Electrolytes: Sodium, potassium, and magnesium supplements or keto-friendly foods (avocados, leafy greens, bone broth) can help.

• Don’t Under-Eat Fat: Ensure you’re eating enough healthy fats to supply energy.

• Ease Into Keto: Gradually lowering carb intake rather than cutting them overnight can reduce the severity of symptoms.

The keto flu is temporary, but once the body adapts, most people experience improved energy, focus, and appetite control. With the right strategies, you can make the transition smoother and set yourself up for long-term keto success.