I’ve been hearing a lot about fasted workouts. What’s the point? I’ve always been told that I should eat or have a pre-workout shake before exercise.
Fast or Feast, New York
Dear Fast or Feast,
Ah, the “Thou Shalt Eat Before Exercise” commandment. You know who came up with it? Food companies. And it’s supplement companies who tell you to have a shake before your workout. Why? So you’ll buy more of their stuff!
There are a few different reasons why someone would want to do a fasted workout.
Endurance athletes sometimes do it to “bonk” on purpose. They do this to train their body to use other energy sources other than the glycogen stores. It also helps them mentally prepare for a bonk in case it happens during a race.
People who want to lose fat often do fasted workouts. To put it in the simplest terms, if you eat before your workout, you’re burning the food that you’ve eaten rather than the fat on your body. You have to exercise for a good chunk of time (30+ minutes) before your body switches to fat-burning mode. If you’re working out on a truly empty stomach (say, like before breakfast) your body will go straight for the fat burning.
And finally, people who want to gain muscle quickly can take advantage of fasted workouts. They will often start with a BCAA supplement, but nothing else. Fasting has been shown to increase growth hormone secretion so fasted weights workouts can help someone to build lean muscle fast.
Working out on an empty stomach has some additional benefits – you don’t have to worry about your food coming back up if you’re doing really intense exercise, you increase insulin sensitivity, you could have more energy during your workout, and more. But that science is beyond the scope of my answer so if you want more information, check out the links below:
If you’ve got a question you would like me to answer on Q&A Thursday, just send me an email at natalie (at) natalieduhamel.com. Your questions will always remain anonymous!