What Happens to Your Energy When You Start Fasting?
If you're fasting for the first time—especially after a big meal like pizza—you might wonder what's happening in your body and why you feel tired. This guide explains the shift your body goes through from burning sugar to using fat, and how to feel better during the process.
⚡ Your Body's Energy Switch
Your body is an amazing machine that can run on different types of fuel. Here's what happens:
- • At first, your body runs on glucose (sugar from food)
- • It stores extra glucose as glycogen in your liver and muscles
- • Once glycogen runs low, your body switches to fat for energy, producing something called ketones
⏰ When does this switch happen?
- • 24 to 48 hours after a big carb-heavy meal
- • Average: around 36 hours
😴 Why You Might Feel Tired
You're in between fuel sources—glucose is gone, but ketones aren't fully ready yet. Think of it like switching from gas to electric in a hybrid car. There's a brief transition period.
Common symptoms during the transition:
- • Low energy
- • Brain fog
- • Headaches
- • Cravings (especially for carbs)
- • Feeling cold
- • Lightheadedness
✅ This is normal and temporary!
💪 How to Feel Better
Drink water often
Stay hydrated throughout the day
Add electrolytes (sodium, potassium, magnesium)
You can use a packet like LMNT or just add salt to water
Take it easy
Light walks are okay, but avoid hard workouts
Rest if you feel tired
Your body is working hard to make this switch
🎉 Good News
- ✓ The more you fast, the easier this transition gets
- ✓ Your body learns to switch fuel sources faster
- ✓ Many people report clearer thinking, steady energy, and better mood once in ketosis
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