Do you exercise FASTED?

Since we’ve recently covered the basics of fasting, how long to do it, how to break your fast and mistakes to avoid (read the blog post here if you missed it) this month’s fasting topic is fasted cardio and other training!

Done correctly, fasted training can increase the benefits of fasting, burn more fat, and help you get more from your training routine.

But done incorrectly, fasted exercise will make fasting difficult, reduce performance, and potentially cause muscle loss. Follow these tips to stay on track and avoid common mistakes!

DO use training to deplete glycogen and achieve ketosis

If you are planning on an extended fast, scheduling exercise beforehand can help deplete your glycogen levels and achieve ketosis faster. 

Some scientists call this a “metabolic switch,” and flipping it can enhance the health benefits of fasting[1].

DO go for walks and light aerobic training while fasted 

Fasted exercise burns more fat than doing the same exercise in a fed state, and low-intensity walks or other light aerobic exercise are the perfect way to enhance body composition and weight loss results from your fasting regimen[2][3].

DO consume protein after fasted weight training

Some people prefer doing their weight training in a fasted state. While there are some potential downsides to this (which I’ll discuss more in a moment), it’s fine if you enjoy it.

However, it’s generally a bad idea to continue fasting after you hit the weights. Strength training increases your protein needs, and eating protein after you train can help recovery[4].

Make sure you eat a meal high in high-quality, complete protein shortly after resistance training for best results!

DON’T train hard during an extended fast period

Extended fast periods lasting a full day or longer can be great for your health, but they’re not an ideal time for hard training.

The lack of calories and protein can impair performance and recovery, and may even result in loss of muscle mass[5]. 

Keep your high-performance training sessions separate from long fast periods.

DON’T lift weights fasted if you’re a “hardgainer” or training with high volume

Some people prefer fasting while weight training, but this is a bad idea if you’re someone who has trouble gaining muscle or if you’re training with ultra-high volume.

Your body needs protein, calories, and sometimes healthy carb sources to support goals like that.

Instead you can:

  • Avoid fasting until you reach your muscle mass goal, or
  • Fast occasionally for health benefits but keep it separate from your high-volume training sessions.

DON’T compete during a fast period 

Competing on an empty stomach is fine, but you should never compete in the fully fasted state. Again, there are tons of health and wellness benefits to fasting, but it’s not the optimal condition for competitive performance — many studies show this to be true[5].

Personally, I like to do my light cardio fasted, medium-intensity training in a low-carb fed state, and do any intense, high-volume, or heavy training in a fully fed state after a full carb-up. 

The Science