Working Out While Intermittent Fasting: The Perfect Weight Loss Combination?

Is ok to combine intermittent fasting and working out? Yes, and you can get even better weight loss results by working out while intermittent fasting.

If you’re trying intermittent fasting or you’re fasting for other reasons and still want to get your workouts in, there are pros and cons to consider before you decide to work out in a fasted state.

Some research shows that working out while fasting might not be ideal. While others say exercising in their intermittent fasting window gave them the best results. 

So who do you believe? You don’t want to ruin all the work you put in for intermittent fasting without any results to show for it. And on top of that, you could not even be getting the best benefits from working out.

Here I’ll show why you should try working out on an intermittent fasting diet to maximize your results, so you don’t lose muscle mass but still lose weight.

Working Out While Fasting: Pros and Cons

So what is the intermittent fasting diet, and why does it work?

Intermittent fasting is a diet that cycles between periods of eating and fasting. It’s been around for centuries, but it’s become more popular recently as people have realized its potential weight loss benefits (1).

Intermittent fasting works because it helps you eat fewer calories overall. When you’re in a fasting state, your body isn’t taking in food, so it has to use up its backup stored energy which is your body fat.

This leads to weight loss and fat loss. Calorie reduction and burning fat stores for energy create a powerful combination for weight loss while burning fat so you can have a tone and tighter body (2).

What happens if you work out while fasting

When you work out while fasting, your body won’t have any quick-burning sugars or carbohydrates for fuel, so it has to tap into its next fuel backup source, which is your body fat.

Unfortunately, many aren’t able to lose weight from working out because they eat a bunch of carbs beforehand. Your body will prioritize burning those carbs for energy instead of fat stores.

Having carbs prior to your workout is a great strategy if you’re an athlete or bodybuilder who wants to maximize their size and strength. But if you’re goal is to lose weight and burn fat then having carbs prior can impede your results.

You also have carbs stored in your muscle called glycogen. You’ll first burn through the stored glycogen and then tap into your fat stores. So by working out when fasted, you can quickly burn through the fat stores and start burning up body fat (3).

Benefits of Working Out an Empty Stomach

When you work out while fasting, there are a few benefits to consider:

You’ll burn more body fat. When you’re fasting, your body isn’t taking in food, so it has to use up its backup stored energy which is your body fat. This leads to weight loss and fat loss.

The leanest I’ve ever been is when I’m consistently working out while fasting. So it’s by far one of the best tricks to maximizing and speeding up your results when working out.

Lowers hunger. When you work out on an empty stomach, you’re less likely to crave sugary and carb-heavy foods because your body won’t be looking for an immediate energy source.

If you’re at first hungry when working out, try to push through it, and you’ll most likely notice your hunger starts to subside.

And studies have found you end up eating less later too (4). Not sure why this works, but it might have something to do with burning your fat stores for fuel.

Better mental clarity. Intermittent fasting has been linked with better mental clarity and focus (5). Your blood sugar and insulin levels will be stable when fasting, which helps clarity.

And your body isn’t working to digest and process food which can hoard blood flow away from your brain.

You also won’t be bloated as you’re trying to digest the food you ate before working out.

Increased autophagy. This is a natural anti-aging process in your body when it clears out the old damaged cells so they can be replaced with newer, healthier cells.

Autophagy is essential for slowing and reversing the aging process keeping you healthier and looking younger.

Studies have found intermittent fasting enhances autophagy as well as exercise (6). In theory, you could multiply your autophagy when working out and fasting.

Cons of Working Out While Fasting

There are also a few cons and possible side effects to working out while fasting:

You might not have as much energy. When you’re fasting, you might not have as much energy as you would when you’re not fasting. This could make it harder to exercise at your usual intensity level.

I’ll admit it’s much easier to get motivated to work out when you’ve just ingested some sugars or carbs and get that blood sugar spike.

So you’ll have readily available fuel to burn for energy, and it’s just a lot easier. It takes time for your body to adapt to using your fat stores and stored glycogen as fuel.

You might lose muscle mass. You could start to utilize your muscle as a fuel source when working out fasted, which could cause a loss of muscle mass.

So if you’re a bodybuilder who wants to maximize their muscle gains, working out when fasted might not be the best idea.

But I’ve found no significant muscle mass loss, but you can get stronger and even build muscle when you’re working out and fasting the right way. Studies have found intermittent fasting and strength training maintain or even improve lean body mass (7).

Your body actually produces more growth hormone when fasted which is beneficial for muscle growth (8).

You could get lightheaded/fatigued. if you’re used to eating before you work out and haven’t been doing intermittent fasting, then you could feel weak, dizzy, or lightheaded.

Since you won’t have any sugars or carbs for energy, it’ll cause your blood sugar to drop since your body is used to being a “sugar burner.”

It’ll take time to adapt and adjust to using your stored glycogen and fat stores instead of recently ingested sugars and carbs.

It can be harder. Working out while fasting will give you better results for weight loss, but it’s no easy ticket. The hunger can be difficult if you’re not used to working out during your fasting window.

Like in the last section, if your body is a “sugar burner” it’ll feel more tired and lightheaded. If this is the case with you, slowly progress into the workouts until your body adapts. So start walking for a little bit and see how you feel, then go from there.

So should you work out while fasting?

The pros definitely outweigh the cons, so if you’re able to manage it, working out while fasting is worth a try.

Working Out When Fasting Results

intermittent fasting working out before after

If you want to maximize your fat loss and weight loss, improve your mental clarity, and increase your autophagy, then exercising while fasting is very effective.

But if you’re not used to it, it could be some time before your body adapts.

Your results will depend on how long you’ve been fasting and the intensity of the workout. The longer you’ve been fasting, the more effective the fasted exercise will be for burning fat.

The longer you’ve been fasting, the more time your body has had to burn through whatever you last ate, and are now using backup fuel sources instead.

This is why it’s ideally best to workout towards the end of your fast to maximize your results.

But with that said, many are at the hungriest in the last couple hours of their fast. And then it’ll be a lot harder to push yourself in the workout.

But there are a few tips you can use…

Drinking coffee will naturally fight the feelings of hunger while giving you an energy and metabolism boost (9).

Add in C8-MCTs like the one in this keto coffee creamer to enhance fat loss. These MCTs are your body’s preferred source of MCTs that quickly converts to ketones in your liver.

Ketones are made from your body’s fat stores for fuel, like when on the keto diet. Taking these MCTs when fasted helps to trigger a “metabolic switch,” allowing your body to burn even more fat for fuel.

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You can also take amino acids before working out to prevent muscle catabolism and for an energy boost.

It’s ideally not best to take BCAAs when fasting since they can combine to form protein in your body and cause an insulin response.

But if you take them just before or while working out towards the end of your fast will prevent muscle breakdown, give you more fuel for the workout, and keep you in a semi-fasted state.

So you could end up getting better overall results by taking BCAAs just before working out than nothing at all and not doing the workout or didn’t train as hard because you felt too tired.

Then for best results, have your first meal time to break your fast not too long after working out.

If you lifted weights, the insulin spike post-workout and the first meal to break your fast would be beneficial for muscle. It’s anabolic and will promote lean muscle mass and even fight off other detrimental hormones like cortisol (10).

Intermittent Fasting Workout Schedule

The best time to work out while fasting is near the end of your fasting window, and then break your fast not long after you’ve finished your workout.

But just because your schedule doesn’t allow this doesn’t mean you still can’t get great results working out while fasting.

In the morning: For many who can get up early enough, it can be most convenient for their schedule to work out early in the morning.

While this isn’t ideal, working out near the end of your fasting window, you’ll still get some great results.

I’d make sure you have had at least a couple of glasses of water that you have had time to absorb into your body before working out.

You’ll have more energy when hydrated, and you’ll be less likely to get injured. Be sure to have some coffee for the energy and metabolism boost and put some keto MCT creamer to get those ketones flowing.

After finishing the morning workout, it’s best to keep fasting until it’s time to break your fast. It’s a myth that you must eat immediately after working out, or you’ll start breaking down muscle.

Studies have found protein timing to be good for many hours after working out (11). While it might be best to do it right after, you can still get results waiting until your fasting window is over.

At night: If you’re working out at night, then this may be the least idea for getting results since you may not have been fasting as long.

Depending on when you started your fasting window, you may not be that far into your fasting to maximize your results.

Ideally, time your work out so you’ll be the furthest into your fast. This will make it easier to tap into your fat stores for fuel. Also, if it’s too early in your fast, you could become too hungry, making it hard to sleep and keep fasting until your window is up.

But if you’re practicing intermittent fasting with OMAD (One Meal a Day), then working out in the evening before having your one meal for the day for dinner is ideal.

Twice a day: if you combine intermittent fasting with working out twice a day, then it’s best to work out early in the morning and right before your fasting window ends.

So if you started your fasting window the evening before with dinner, then in the morning you could lift weights, and then for the second workout, you could do some fasted cardio right before your fast ends.

This will be harder than working out just once during your fast but it can produce great results if you can push through.


If your goal is to lose weight, burn fat, have better mental clarity, and increased autophagy, amongst other health benefits, then working out while intermittent fasting is fantastic.

But remember that doesn’t mean it’s always going to be easy. You’ll be hungrier, possibly feel weaker, and it could be easier to become fatigued.

The leanest I ever am is when I’m consistently working out while fasting. You start tapping into your fat stores and burning through them quicker. It’s the fastest way to tone up and lean down fast.

I like to work out near the end of my fasting window with weight lifting or strength training first so I can use up my stored glycogen and then do cardio after so I really start burning through my fat.

Just because your schedule doesn’t allow you to work out right before your fasting window ends, that doesn’t mean you still can’t get some great results working out at other times.

In the morning, ensure you’re hydrated and do not eat afterward until your fast is done. In the evening, try to time it so you’ve been fasting the longest. Twice-a-day workouts can be hard but can produce great results when fasted if you can push through.

Giving yourself the time to adapt to working out when fasted will be key. We’re usually used to being “sugar burners” and using recently eaten carbs for fuel. So when we try to work out fasted, the body is thrown for a loop when the quick-burning sugars aren’t there anymore.

Just give it some time and allow your body to adapt so you can reap the health benefits of combining intermittent fasting and exercise.