6 Fasting Tips for Fitness Fans

Fasting has proven health benefits for the average person. But what if you’re exercising heavily, playing lots of spots, or engaging in any other type of strenuous physical activity? Can you still fast?

Ben Greenfield
5-minute read
Episode #148

Here are my top 6 steps to successfully implementing calorie restriction without damaging your body: 

Fasted training upregulates muscle protein translation, allowing for faster muscle recovery and growth.

  1. Step #1 – Rather than fasting for 24 hours or longer, limit yourself to a 12-16 hour fast. The most practical and effective fasting strategy used by myself and the active individuals I coach for fat loss and muscle gain is a 12-16 hour fasting window for every 24 hour cycle. For example, you can eat dinner at 8pm, then eat nothing until breakfast or an early lunch sometime between 8am and 12pm the next day. This is called “intermittent fasting,” or “IF’ing.”
  2. Step #2 – Don’t fast every day - skip your fast on high volume days. On high volume days, such as your biggest exercise day of the week or a weekend that might involve several hours of exercise, don’t fast. Just eat when you’re hungry. The risks simply outweigh the benefits when you combine calorie restriction with high volume exercise. fasted training upregulates muscle protein translation, allowing for faster muscle recovery and growth
  3. Step #3 – Don’t do hard or long workouts fasted. An easy morning exercise session such as a swim, run, bike ride, or body weight workout session that follows an overnight fast is fine. So is a short 10-60 minute high intensity interval training session, assuming you listen to your body and you’re able to maintain your goal intensity, recover well, and eat a big breakfast afterwards. However, any workout that is A) hard and longer than 60 minutes or B) easy-to-moderate and longer than 2 hours, should not be done in an overnight fasted state. This is a quick path to unhealthy levels of hormone depletion and muscle loss!
  4. Step #4 – Some foods are OK to eat when fasting. There are several foods that will allow your body to maintain low levels of blood sugar and low levels of the hormone insulin (both of which can help you lose fat faster) but do allow for adequate energy levels and even enhanced fatty acid utilization during a fast. By consuming these foods, you can also lower the amount of hormonal or metabolic stress you may experience when combining fasting with high levels of physical activity. These foods include: MCT or coconut oil, essential amino acids or branched chain amino acids, coffee or green tea and spirulina, chlorella, greens powders or greens supplements.
  5. Step #5 – Only occasionally, do a 24 hour fast. Every 2 weeks to 2 months, you can choose one day on which you’re not going to exercise at all and you’re simply going to clean out your body and allow for enhanced cellular autophagy (basically, clean-up of your body’s junk). This is especially important for very active people who are eating thousands and thousands of calories per day. This occasional complete day of rest for your muscles, your adrenals, and your digestive system can be very therapeutic, and it is a strategy I use in the Mighty Mommy 12-Week Belly Burn Plan. Check it out if you haven't already.
  6. Step #6 – Be careful with fasting if you’re female. Many women find that fasting causes sleeplessness, anxiety, and irregular periods, among a myriad of other hormonal dysregulation symptoms. I suspect that it may be an ancestral or evolutionary mechanism that seems to allow men to simply do better heading off into the hills to hunt, gather, or fight in a state of calorie restriction (or in the modern age, hit the gym hard) – while the same scenario sends many women into a complete metabolic and hormonal downspin. I’ve found that when it comes to maintaining health and hormonal status for my female clients, the occassional complete 24 hour fast described in step #5 can be far more effective and less stressful than daily intermittent fasting. If you are female and simply cannot resist the idea of daily intermittent fasting, I highly recommend you at least implement the extra nutrient steps outlined in step #4.

Finally, you may wonder if the Get-Fit Guy fasts.

The answer is…yes!

Here’s how: I usually finish my workouts around 6:30pm, and then I eat dinner around 7pm, have a snack such as coconut milk with protein powder around 8pm, then generally don’t eat breakfast until around 10am the next morning, at which point I’ll usually make my world-famous high-fat kale shake, which you can see me making in this video. This is my standard practice 5 days per week, and then I generally just eat when I’m hungry on my heavier exercise volume days, which are usually weekends.

If you want to learn more about why fasting can be good for your body – especially for enhancing your recovery from workouts – then you may also want to read my article: “26 Top Ways To Recover From Workouts and Injuries with Lightning Speed.”

For questions, comments, or feedback about fasting for fitness, check out Facebook.com/GetFitGuy!

Finally, want free fitness and weight loss tips for your unique shape? Check out GetFitGuy.com.

Fast lane image courtesy of Shutterstock.


All content here is for informational purposes only. This content does not replace the professional judgment of your own health provider. Please consult a licensed health professional for all individual questions and issues.

About the Author

Ben Greenfield

Ben Greenfield received bachelor’s and master’s degrees from University of Idaho in sports science and exercise physiology; personal training and strength and conditioning certifications from the National Strength and Conditioning Association (NSCA); a sports nutrition certification from the International Society of Sports Nutrition (ISSN), an advanced bicycle fitting certification from Serotta. He has over 11 years’ experience in coaching professional, collegiate, and recreational athletes from all sports, and as helped hundreds of clients achieve weight loss and fitness success.