Keto flu refers to a set of symptoms some people experience when they first start a ketogenic (keto) diet, which is high in fats and very low in carbohydrates. It’s not an actual flu caused by a virus, but rather a temporary reaction as your body adjusts to using fat for fuel instead of carbs (a state called ketosis). Here’s a rundown:
### Common Symptoms
- Fatigue
- Headache
- Nausea
- Dizziness
- Irritability
- Brain fog
- Muscle cramps
- Trouble sleeping
### Why It Happens
When you drastically cut carbs, your body depletes its glycogen stores (stored carbs in the liver and muscles), which also releases water—hence the initial weight loss people often notice. This shift can mess with electrolyte balance (sodium, potassium, magnesium), and your brain, used to running on glucose, takes time to adapt to ketones. Insulin levels drop too, which can amplify the electrolyte loss through urine.
### How Long It Lasts
Typically, it kicks in within a day or two of starting the diet and lasts anywhere from a few days to a week or two. Some breeze through it, others feel it harder—it depends on your starting point, hydration, and how strict you go.
### How to Deal With It
1. **Hydrate**: Drink more water than usual—aim for at least 2-3 liters a day.
2. **Electrolytes**: Up your sodium (think broth or salted food), potassium (avocado, spinach), and magnesium (nuts or a supplement).
3. **Ease In**: Don’t go from 200g of carbs to 20g overnight—taper down over a few days if you’re prone to feeling rough.
4. **Fat Up**: Eating enough fat (like coconut oil or butter) can help your body switch fuels faster.
5. **Rest**: Sleep and take it easy while your body adjusts.
It’s usually a short-term thing, and most people feel better once they’re “fat-adapted.” If it drags on beyond a couple of weeks or gets severe, it might be worth checking with a doctor—could be something else or a sign the diet’s not jiving with you.
