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should I work out fueled or fasted?

Should you work out fueled or fasted? We get asked this question by many of our clients and because it is a controversial topic and deeply individualized, it's time to explore the fasted workout terrain.

Let's dive into the benefits & downsides of each perspective to fully grasp the bigger picture of what is happening within our bodies when we do one or the other, as well as some indications on when to do which option.


benefits of fueled workouts:

  1. gives the body fuel + energy to complete the workout

  2. can reduce the stress of a high intensity / long workout on the body

  3. can provide nutrients for hydration / muscle contraction to prevent cramping + encourage hydration

drawbacks of fueled workouts:

  1. if the meal is too large prior to working out, you may feel sluggish or tired during the workout

  2. may cause burping or unpleasant aftertastes during the workout [we've all been there!]

  3. your body will utilize the pre-workout fuel for energy rather than tapping into its own stores [leading to less fat burned overall]

when to utilize fueled workouts to your advantage:

  1. if you are in the luteal phase of your cycle [the 2 weeks leading up to the beginning of bleeding]

  2. if your workout will be > 60 minutes OR extremely high intensity

  3. if you are pregnant / nursing

  4. if you are feeling hungry prior to completing the workout

how to fuel prior to a workout:

  1. aim to eat 30 minutes - 1 hour before a workout

  2. fuel with high quality carbohydrates + fats [i.e fruit + nuts]

  3. eat something you know your stomach can tolerate during a long / high intensity workout session


benefits of fasted workouts:

  1. allows the body to tap into stored glucose [glycogen] + fat for energy

  2. workouts are not as heavily impacted by your immediate food choices

  3. requires less planning [you can just lace up your shoes and go!]

drawbacks of fasted workouts:

  1. can lead to "bonking" [an energy crash] during the workout

  2. if workout is too long / hard, your body will start to break down muscle tissue for energy

  3. this can also put extra stress on the body, raising cortisol levels and negating the benefits of the exercise on the body [especially if done chronically]

when to utilize a fasted workout to your advantage:

  1. when working out first thing in the morning

  2. if you are in the follicular phase of your cycle [the first 2 weeks of your cycle]

  3. if you are working out for < 60 minutes at a moderate to low intensity

  4. if you are feeling great!

When considering whether you should fuel before your workout, tune in to your body's cues to see what it is telling you [note: this might change from one day to the next]. Both fasted + fueled workouts are beneficial, and there is no one size fits all approach!


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