The goal of this article is to make intermittent fasting and morning workouts simple. We’ll discuss the science both for and against fasted workouts to help you make an educated plan on when to work out and break your fast.

We’ll explain as fast as I can. Let’s HIIT it!

Intermittent Fasting and Morning Workouts Ryan and Alex Duo Life Ryan Paddleboard

intermittent fasting and morning workouts

A lot of people think they can’t do intermittent fasting if they work out, because they’ll feel too depleted. Others are scared that they shouldn’t because they’ll risk losing hard-earned muscle.

Both concerns are valid but not 100% true according to the science.

The good news is that a growing number of data shows that morning workouts and intermittent fasting will not jeopardize muscle mass. Our experience corroborates that — as long as you’re sufficiently strength training and not under-eating.

We have been researching and self-experimenting with fasting since 2018. The goal of this article is to make intermittent fasting and morning workouts more straightforward by tackling your concerns head-on.

Plus we’ll share what we do not just to feel comfortable while working out and fasting, but how to measure our metabolism to optimize our fasts and when to work out.

For additional, well-researched content backed by personal experience, check out the articles on our fasting page.

Why fasting and morning workouts work

First, let’s discuss how intermittent fasting for muscle gain works.

As described in our article titled, “The Health Benefits of Intermittent Fasting,” after a meal, excess glucose from the blood is stored in the liver, muscles, and fat cells.

Here’s Why You Won’t Lose Muscle

So, how does the body know not to burn muscle, but to instead to tap into our fat stores after 16 hours, 20 hours, or [fill in the blank] hours of no eating?

First, there’s more HGH

One reason for this is due to human growth hormone (HGH). Human growth hormone is vital in muscle growth, body composition, cell repair, and metabolism.

It grows muscles, increases strength, and all while reducing recovery time. For this reason, the Olympics banned it as an illegal substance and steroid in athletes in 1989.

Produced naturally by the pituitary gland, many studies have shown that fasting drastically increases the production of human growth hormone. Research cites an increase between 100%-2000% over 24 hours of fasting.

In any case, during fasting human growth hormone levels can more than double, which preserves muscle and strength.

What’s more, is HGH production occurs while fasting, while sleeping, and while exercising. Therefore, intermittent fasting can be a powerful tool to gain muscle.

A word of warning: while fasting, it is still essential to consume enough calories and exercise with strength training. Like any weight-loss diet, small amounts of lean mass (including muscle) are lost along with the fat mass.

The good news is that studies have shown that muscle mass can be maintained or grown as long as you perform proper strength and resistance training.

Repeat: to minimize your muscle loss, you have to consume enough calories during your fasting window and strength train!

If not, you’re at risk of losing 1-2 lbs. of muscle mass over a few months, which would likely be the case whether or not you’re following an intermittent fasting plan.

In short, our bodies are smart enough to know to burn fat before muscle.

Then, there are 24 hours of protein synthesis

Here’s another reason why you won’t lose muscle.

Muscles don’t grow and recover in an hour after exercise. Instead, it takes them a day or longer to recover. Protein synthesis is the process of rebuilding the muscles broken down during exercise and helping them recover stronger.

This study shows that the rate of protein synthesis gradually builds and peaks 24 hours after a resistance workout.

That means that as long as we fuel our body with quality carbs and protein during the 24 hours after a workout, we are still supporting muscle growth and recovery.

While this is just one study, I’m confident that fasted workouts have helped me gain muscle mass more efficiently while maintaining a more trim waistline.

Which leads me to another good reason to try intermittent fasting with morning workouts.

Here’s Why You Will Lose Weight

While it’s not widely accepted or scientifically proven that fasted workouts are good for muscle gain, it is for fat loss. This is for a couple of reasons.

It’s stored fat or bust

Simply put, when you’re in a fasted state your body can’t burn glycogen (stored carbs), so it has to burn stored fat.

But that’s only if you’ve been in a fasted state long enough to deplete the glucose and insulin in your bloodstream. At that point, a metabolic shift occurs to start burning the glucose stored in fat for energy.

Depending on your diet, insulin sensitivity, and exercise level, “long enough” is somewhere between 12-36 hours.

If you maintain a poor diet, a 16/8 intermittent fasting schedule may not be long enough for you to realize a positive metabolic impact. That is why it’s crucial to have a well-balanced diet full of vegetables, beans, and legumes.

Are morning workouts and if best?

Now that you know intermittent fasting and working out won’t destroy your muscle mass, let’s talk about the best time to work out.

Dr. Jason Fung, a world-leading expert in intermittent fasting and author of the helpful book, The Complete Guide to Fasting, thinks that the best time to work out is at the end of your fasting window.

So, if you’re doing a 16/8 intermittent fast ending at 9am, start your workout around 7 or 8 am. Then follow up with a healthy, protein-heavy breakfast.

He recommends this for several reasons: the increased human growth hormone discussed earlier, and the fact that your body is primed to have a great workout as it’s already in “fight or flight” mode.

So, are morning workouts and intermittent fasting the best route for your optimal health? There’s only one way to truly find out.

Intermittent Fasting and Morning Workouts while Measuring Metabolism

In 2011, before I (Ryan) even understood the science, I first tried a morning HIIT cardio program called Max T3. The trainer, Shaun T, suggested fasting for two hours after each workout. My results were shocking at the time, and still memorable enough to be talking about nearly a decade later.

I quickly lost 5 pounds in the first 2 weeks. And the only change I made was doing the short workouts (12 minutes each and only 3 days a week) and fasting for two hours after.

Cool, it seemed to work. But now I have the data to back it up as both Alex and I have now studied intermittent fasting and workouts for the better half of a decade, (both intermittent and long-term fasting, like with a 5-day fasting mimicking diet.)

Optimize IF and Workout Times According to Our Metabolism

Our recommendation and experience is that, no matter how much you research, it’s best to self-experiment and self-track. Even us, a couple who exercises, eats, and sleeps together, our bodies’ metabolisms and responses are fairly different. 

We only came to truly appreciate this over the past year, since we’ve been tracking our metabolism in real-time with our Lumen devices.

We used to blindly follow a 16/8 intermittent fasting plan because that was the best we could do. Now, there’s no more guesswork because Lumen tells us what our bodies are doing. And it’s incredibly detailed, because it reads the CO2 from your breath to tell you, for example, that your body is currently burning 95% fat and 5% carbs.

(Here’s a photo of a recent measurement I had showing just that.)


Lumen Metabolism Tracker Score_Intermittent Fasting and Morning Workouts

Using data like this, we can make an easy judgement call on when to plan a workout and when to break our fasts.

(In the scenario above, given that I was squarely in fat burn mode, I’d move my workout until a little later!)

Lumen is the best tool we’ve found to gauge this, because even how we’re feeling and our hunger levels don’t always correspond to what our metabolism is doing. And what a bummer to end a fast arbitrarily when your body is still burning fat… or make your fast longer than it needs to be, adding unnecessary stress to your body!

By the way, if you’re interested in learning more, we share our full experience in our Lumen review as well as our article, “Stages of Fasting by Hour,” where we also share our Lumen metabolism data.

If you have more questions, write them in the comments and here’s our discount code for $50 off Lumen with RYANANDALEX. Good luck!

INtermittent Fasting and Morning Workout Tips

When you start, measuring your progress as described above, and following these tips, you should feel stronger and more athletic, not weaker.

#1: Eat enough

Many people on IF plans lose weight because it’s harder to overeat in a shorter time window. But, under-eating is just as problematic, especially if you are trying to maximize your results from a workout plan.

Track your calories and make sure you’re eating enough. We share how to calculate and track your calories in our 30-Day Weight Loss Challenge.

#2: Hydrate a lot

Just because you’re not eating, doesn’t mean you’re not drinking water. Do not let fasting cause dehydration. Start your day with a big glass of water and carry a full water bottle with you as a reminder.

Drink at least one-half of your body weight in ounces. For example, an individual who weighs 200 pounds should drink at least 100 ounces.

If you want to keep it really simple and avoid math, just try drinking a gallon of water a day and see how you feel.

#3 Ease into it and optimize

Be patient during your transition. You’ll likely find that on moderate to high-intensity workout days you want to eat right after.

If you can’t resist the hunger, have a banana and peanut butter. If it doesn’t get easier, move your workouts closer to the start of your eating window.

When you start, it might feel like you have no energy in the morning. If after one month, this doesn’t improve, try eating more carbs at night to get your glycogen levels higher.

#4 Be Patient and monitor progress

As always, you need to pay close attention to your body’s response to a diet or exercise change. But, you also need to be patient. Don’t expect it to take days or weeks. It will take months.

Just like intermittent fasting is hard at first, so are fasted workouts. It takes time to break through that barrier.

To understand if you are making progress, pay attention to your workout performance and how you feel throughout the day. Then, you need to track your progress with a body measurement chart.

As engineers, we always say, “What’s measured gets improved.” How can you know if you are gaining or losing muscle if you aren’t tracking your body measurements?

Tracking progress properly involves taking body measurements, photos, weight on the scale, and measuring body fat percentage.

If you’re really serious about optimizing your workouts and the health benefits of fasting, you need to look at the Lumen metabolism tracker. It’s a recent discovery of ours and a complete game-changer. We talk all about our experience and results (that came incredibly easy) in our full review of Lumen

Recommended Morning Workouts

At Ryan and Alex Duo Life, we have created two highly effective, free programs with over 4,000 users currently.

Both of them are 8-week programs with workouts three days a week. Don’t worry, when you work out your full body with proper intensity, you only need to work out three times a week.

Take a look at our free programs optimized for weight loss and strength building:

Closing Thoughts on Intermittent fasting Workouts

We hope this article has helped you time your workouts while intermittent fasting.

Think of intermittent fasting with morning workouts as a tool in your healthy living toolbox. To properly use that tool, you need to try it and understand how it helps you get the job done.

If it helps, incorporate it into your routine while still utilizing other effective healthy living tools. But, if it doesn’t work — meaning you can’t do it without feeling weak, slow, or dizzy — that’s fine. There are many other ways to live a healthy lifestyle.

You don’t have to work out in the morning or in a fasted state to get the benefits of intermittent fasting. And, you don’t have to intermittent fast to realize the benefits of morning workouts.

There are cases where people don’t like morning workouts and intermittent fasting. It’s especially challenging if your schedule only allows very early morning workouts.

Working out at 6 AM and then not being able to break your fast until 11 AM is challenging — studies show that your hunger levels will be out of control — especially after a high-intensity workout. That can be a deal-breaker.

The best thing you can do is track it with something like a Lumen metabolism tracker and by keeping a journal of your progress. (And don’t forget our Lumen discount code RYANANDALEX for $50 off).

Leave any specific questions about intermittent fasting and working out in the comments below. We prefer that to email because the discussion helps all future readers. Thanks!

For general questions about fasting, such as why you’re not losing weight on intermittent fasting, head over to our Fasting Page. Or download our Fasting Bundle below. 

Intermittent and extended fasting bundle - printable pdf guide

The Proven Fasting Bundle (Printable PDF Guide)

Read by 143,364 fasters in 2022 alone, the Fasting Bundle is the structure and tools you need to succeed.

  • Intermittent and alternate-day fasting meal plans
  • Checklist for before, during, and after a prolonged fast
  • Benefits, challenges, and a beginners how-to guide

Plus, we're just an email away for support.

30-Day Weight Loss Challenge Tracker Form V2 Ryan and Alex Duo Life

30-Day Weight Loss Challenge

As engineers with a combined twelve years of health coaching experience, we needed to create a data-driven way for our clients to sustain weight loss.

Too many weight loss challenges involve a long list of what you can, cannot, and need to do every day. We’ve reduced the overwhelm and only require you to track five numbers a day — calories, steps, fiber, sleep, and waistline.

You’ll track five numbers daily to give you the highest return for sustainable weight loss. As a bonus, we’ll share our Weight Loss Bundle, which includes strategies, progress tracking tools, and additional weight loss plans.

Learn more about the program.

As Seen In Feature Bar Ryan and Alex Duo Life

Hey we're Ryan and Alex

The creators of Ryan and Alex Duo Life. We are a husband-wife duo and “lifestyle engineers.”

After eight years working in the corporate world as engineers, we left our high-powered jobs to tackle our true passion — helping couples engineer their best lives.

The synergy of our engineering minds and ten years of health coaching experience produced Ryan and Alex Duo Life. Our mission is to help you transform your bodies, minds, and relationship as a couple.

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