Intermittent Fasting for Athletes: Is It a Good Idea?

Intermittent Fasting for Athletes: Is It a Good Idea?

Intermittent Fasting for Athletes

Over the past decade, intermittent fasting has been catching momentum.

Mounting evidence has shown its positive impacts on mental cognition and health markers.

But what if you’re an athlete?

Is fasting an effective tool for increasing performance?

Yes and no.

Today, I’ll analyze the pros and cons of IF for both strength and endurance athletes.

I’ll also share some exclusive tips that will help you get the most out of intermittent fasting.

Let’s dive in!

I. Intermittent fasting for strength athletes

Let's get this out of the way…

A high carbohydrate diet is crucial for strength training.

The research is clear. But you’re probably wondering: 

How does fasting affect muscle building and workout performance?

This is where it gets interesting:

Multiple studies have shown that fasting over a period of weeks does not affect muscle building.

Need an example? This study compared the effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males.

The results showed that the fasted group lost a greater amount of fat versus the control group. Muscle mass was maintained completely in the fasted men.


There is an exception to the rule:

Research has shown that fasting may impair reaction times in sprinters.

If you’re a professional, this is something to consider.

Key takeaways:

1. A carbohy​​​​​​​drate diet is crucial for muscle building.

2. You can preserve muscle mass on an intermittent fasting diet.

3. Fasting may not be optimal for sprinters.

II. Intermittent fasting for endurance athletes

When it comes to endurance training, intermittent fasting is a mixed bag…

Here’s the deal:

Glycogen plays a crucial role in performance and fatigue management for endurance athletes.

But what is it?

Glycogen is a form of glucose, derived from carbohydrates.

 A high carb diet equals more glycogen stores.

The problem with fasting is that it depletes these glycogen stores which leads to diminished performance in longer bouts of exercise.

(Also read: Is It Good to Run in the Morning Before Eating?)


Despite the negative impact of fasting on performance, it’s still a worthwhile tool for improving general health.

The easiest way around the problem is to train in the evening.

Another option is to increase training frequency and decrease the length of individual sessions.

Key takeaways:

1. Fasted training isn’t optimal for endurance work.

2. The easiest solution is to perform training sessions in the evening.

III. Pro tips for intermittent fasting

#1 Avoid fasting for high volume weight training and endurance work.

A great quote from Ori Hofmekler is, ”You can’t achieve maximum longevity and fitness at the same time; choose one.”

The takeaway message?

Don’t try to be a jack of all trades!

If your goal is maximum performance, you need to tailor your nutrition and eating patterns to that specific goal.

 This is especially true for high volume weight training and endurance sports such as cycling.

Stick to a high carbohydrate diet and ONLY implement IF using the alterations I outlined above.

#2 Use time-restricted feeding (TRF).

There are three different variations of intermittent fasting:

1. Alternate day fasting (ADF)

2. Whole day fasting

3. Time restricted feeding (TRF)

TRF is your best choice, since it’s less restrictive and you’re able to mold the feeding/fasting windows around your schedule.

The simplest ratio for beginners is the 16:8 approach, wherein you fast for 16 hours and have an 8 hour window to eat your daily intake of calories. (This includes sleeping hours.)

Here’s what a typical day of fasting might look like.

  • Wake up at 8am
  • Fast from 8-12pm
  • Eat meal 1 at 12pm
  • Eat meal 2 (pre-workout) at 4pm
  • Train from 4.30-5.30pm
  • Eat meal 3 (post-workout) at 7pm
  • Feeding window ends

#3 Eat enough calories.

A common mistake athletes make when trying intermittent fasting is not tracking their calorie intake.

This is a HUGE no-no.

Eating enough calories is critical for performance and keeping your body weight stable.

How do you track calories?


Download MyFitnessPal (compatible with iOS, Android, and PC devices) and follow the steps below:

1. Log in.

2. Set up your goals.

Intermittent Fasting For Strength Athletes

Next, you’ll need to click Edit on the Daily Nutrition Goals tab.

Intermittent Fasting For Endurance Athletes

3. Now you can track calories.

Pro Tips For Intermittent Fasting

For more info, head over to the MyFitnessPal website.

#4 Take BCAAs before fasted training.

If you want to preserve muscle mass during fasted training, take BCAAs pre-workout.

BCAAs don’t raise insulin so they won’t break your fast.

They are also an incredibly effective anti-catabolic agent.


Intermittent fasting is a great tool for weight loss, but if you’re serious about maximizing performance, I wouldn’t recommend fasted training.

Have you tried IF?

I’d love to hear about your experiences and how it affected your performance!

I’ll be answering any questions below in the comments.

Author Bio: Marcus has been training for six years and has developed an extensive knowledge of strength and conditioning as well as weight loss. He runs and offers online personal training services, specializing mainly in muscle building and weight loss.

Enrepreneur. I build websites all around the world an I run everyday. I just can't live without my daily running. Follow me on Twitter for more informations.

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