How to Transition From Keto to Intermittent Fasting

13 November 2025

Switching from the ketogenic (keto) diet to intermittent fasting (IF) can feel overwhelming if you don’t know where to start. But don’t worry—you’re already ahead of the game! Since both keto and intermittent fasting share similar metabolic benefits, the transition can be surprisingly smooth if done correctly.

If you’re wondering how to shift from eating high-fat, low-carb meals to structured fasting without losing energy or feeling deprived, this guide will walk you through everything you need to know.

Why Transition From Keto to Intermittent Fasting?

Before diving into the "how," let's quickly cover the "why."

Both keto and intermittent fasting train your body to become fat-adapted, meaning you primarily burn fat for fuel instead of carbs. If you've been following keto for a while, your body is already efficient at using fat for energy. This makes transitioning to IF much easier compared to someone shifting from a standard high-carb diet.

Some key benefits of switching from keto to intermittent fasting include:
- Simplicity – No more counting macros or obsessing over fat intake.
- Flexibility – IF allows you to eat a wider variety of foods while still maintaining fat-burning benefits.
- Sustainability – Many people find IF easier to maintain long-term compared to strict keto.
- Improved Gut Health – IF gives your digestive system a break, helping reduce bloating and improving gut bacteria balance.

Now, let’s jump into the step-by-step process of transitioning smoothly.

Step 1: Maintain a Low-Carb Diet While Adjusting

One of the biggest mistakes people make when switching from keto to intermittent fasting is suddenly reintroducing high-carb foods. This shock can lead to blood sugar spikes, energy crashes, and intense cravings.

To avoid this, start by keeping your carb intake relatively low but not as strict as keto. Instead of staying under 50 grams of carbs per day, aim for around 100-150 grams. This allows for more dietary flexibility while preventing energy fluctuations.

Foods to Focus On:

- Healthy Fats: Avocados, nuts, seeds, olive oil, and fatty fish.
- Protein Sources: Chicken, eggs, beef, tofu, and fish.
- Slow-Digesting Carbs: Quinoa, sweet potatoes, berries, and whole grains.

Gradually increasing your carb intake while sticking to whole, nutrient-dense foods will set you up for a smoother transition.

Step 2: Start With a 12-Hour Fast

If you’ve been eating keto, your body is already used to longer periods without food. However, jumping straight into a 16:8 fasting window (16 hours of fasting, 8 hours of eating) can be mentally and physically challenging.

Instead, ease into fasting by starting with a 12-hour fast. For example, if you finish dinner at 7 PM, wait until 7 AM the next day before eating again. This gives your body time to adjust without the stress of prolonged hunger.

Once you’re comfortable with 12-hour fasting, gradually increase the duration by an hour or two every few days until you reach your desired fasting window (e.g., 14:10 or 16:8).

Step 3: Keep Protein Intake High

One common problem when moving from keto to IF is muscle loss due to reduced protein intake. Since keto relies heavily on fats, your protein consumption might have been moderate. However, intermittent fasting requires a balance of protein, fats, and carbs to maintain energy and muscle mass.

How to Get Enough Protein While Fasting:

- Break your fast with a protein-rich meal (e.g., eggs with smoked salmon).
- Include a protein source in every meal.
- Consider protein shakes if you struggle to meet your intake.

A good rule of thumb is to aim for around 0.7 to 1 gram of protein per pound of body weight to prevent muscle breakdown.

Step 4: Stay Hydrated and Replenish Electrolytes

One of the most overlooked aspects of intermittent fasting is hydration. Since keto naturally helps retain electrolytes due to low insulin levels, fasting may lead to increased water loss and electrolyte depletion.

How to Stay Hydrated While Fasting:

- Drink plenty of water throughout the day.
- Add a pinch of sea salt to your water to replenish sodium levels.
- Consume mineral-rich foods like leafy greens, nuts, and seeds during your eating window.
- Try electrolyte supplements if you feel sluggish or experience headaches.

Hydration is key to preventing fatigue, dizziness, and muscle cramps, so don’t underestimate the power of water and electrolytes!

Step 5: Adjust Your Meal Timing

Keto often involves eating multiple high-fat, low-carb meals throughout the day. But intermittent fasting works best with fewer meals that are larger and more nutrient-dense.

How to Structure Your Meals:

- Two-Meal Option (16:8 Fasting Window):
- First Meal: Protein-rich with healthy fats (e.g., grilled chicken with avocado and veggies).
- Second Meal: Nutrient-dense with balanced macros (e.g., salmon with quinoa and roasted vegetables).
- One Large Meal Option (OMAD – One Meal A Day):
- A big, satisfying meal with protein, carbs, and fats (e.g., steak with sweet potatoes, salad, and olive oil dressing).

Experiment with different meal frequencies and sizes to see what works best for your body.

Step 6: Listen to Your Body and Adjust Accordingly

Your transition from keto to intermittent fasting won’t be the same as someone else’s—it’s important to listen to your body’s signals.

If you experience excessive fatigue, brain fog, or irritability, it might mean:
- You’re not eating enough calories during your eating window.
- Your carb intake is too low or too high.
- Your fasting periods are too extreme too soon.

It’s okay to adjust and find a comfortable balance rather than following strict rules.

Common Mistakes to Avoid

Making the switch from keto to intermittent fasting can be smooth if you avoid these pitfalls:

❌ Going from keto straight to long fasts – Start with shorter fasting windows and gradually increase.

❌ Reintroducing excessive processed carbs immediately – Stick to whole, nutrient-dense foods to prevent energy crashes.

❌ Ignoring protein intake – Ensure you consume enough protein to maintain muscle mass.

❌ Not drinking enough water or electrolytes – Dehydration can make fasting miserable.

❌ Overeating during eating windows – Focus on balanced meals rather than bingeing.

Final Thoughts

Transitioning from keto to intermittent fasting doesn’t have to be complicated. It’s all about gradual adjustments, mindful nutrition, and listening to your body. By keeping your carb intake moderate, increasing fasting windows at a sustainable pace, and focusing on hydration and protein, you’ll set yourself up for long-term success.

Remember, every body is different—what works for one person might not work for another. Take your time, experiment, and find an approach that fits your lifestyle and goals.

Ready to make the switch? Start small, stay consistent, and enjoy the benefits of metabolic flexibility!