Train Fasted or Fed?

By Chloe McLeod

With so many mixed messages about nutrition before training sessions, it is not surprising that it can be confusing knowing what the best plan of attack is. So, is training fasted a good idea? Here are the ins and outs.

The short answer to this question is a resounding ‘yes’, however it does come with a great big ‘but’ attached. The ‘but’ relating to ‘but it depends on which session’.

The most recent research shows that completing some training sessions fasted, or with low carbohydrate availability, improves the body’s ability to use fat as a source of fuel, store glycogen, along with increased development of mitochondria in the cells. Mitochondria are often referred to as the ‘powerhouse’ of our cells, so more of them can mean better performance.

However, it is not wise to complete all sessions this way, as we need to also be able to use carbohydrates well as a source for fuel; if we do all sessions fasted, this may blunt the body’s ability to do this. Mixing up our sessions between fueled and fasted results in best performance.

So which sessions or what kind of sessions should we need to eat before?

When to Train Fed

Our muscles store carbohydrates as a substance called glycogen. There is enough of this in well-fueled muscles to last for approximately one and a half hours, depending on intensity of session and fitness level. The fitter you are, the more you will likely find you can do without fueling beforehand.

This doesn’t mean you don’t need to fuel; it just means that your body is more efficient, and if you do fuel well, it is likely you will perform even better.

As a general rule of thumb, fueling up before training sessions is recommended in the following situations:

  • Long (more than 1.5hrs) endurance session that includes efforts
  • Higher-intensity sessions more than 1 hour
  • Resistance training sessions

When to Train Fasted

Fasted sessions, or those completed with low carbohydrate availability, are best completed for low- or moderate-intensity sessions. Including some higher intensity sessions fasted is a good idea.

As an example:

  • Training day 1: 1 hour run, easy pace in morning + 2 hour hill session bike in the afternoon – morning session do fasted, afternoon session do fed.
  • Training day 2: 4 hour bike + 1 hour run in morning – do this long session fed

It is important you listen to your body, and individualize how this is incorporated into your training plan due to differences in how well each individual responds to fasted sessions.

As always, you can ensure better outcomes by consulting with the experts you can access with your MX Endurance membership.

(Header photo by Mae Mu on Unsplash.)

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