This is one of the most frequently asked questions in the gym.
Which strategy is best? Should you be doing fasted cardio?
Or should you fuel up first?
Spoiler alert…it depends.
And while this is nobody’s favorite answer, this post will dive deeper into the subject to help you make the best decision for yourself.
What The Studies Say
When it comes to fat loss, there does not seem to be an advantage to fasted cardio.
There are studies which show greater fat oxidation while exercising fasted but these are often shown without discussing what happens post-exercise.
A 2011 study by Paoli showed that exercising after a meal resulted in greater fat oxidation post-exercise than fasted exercise.
The primary energy source used during exercise (fats or carbohydrates) will be relied on less for fuel by the body over the next 24 hours.
Another study in 2014 by Brad Schoenfeld had similar findings leading researchers to conclude that training Fed or Fasted does not appear to have a meaningful impact on overall fat loss.
In 2017, a meta-analysis by Hackett and Hagstrom again concluded there was not a significant difference in terms of body composition with respect to fasted versus fed training.
Additionally, there is not sufficient evidence to suggest that training fasted impairs Muscle Protein Synthesis. Fasted cardio will not impact your ability to build or preserve lean muscle tissue.
However, there is research showing fasted cardio may provide a greater benefit for reducing fasting insulin levels and overall insulin sensitivity.
Questions To Guide Your Decision
With respect to the question of whether or not your training should be fed or fasted, the first question that should be answered is what is your goal?
Are you looking to improve body composition (fat loss)? Improve insulin sensitivity? Performance?
If your goal is to improve your performance, this will be your guiding factor in determining whether training fed or fasted is best for you.
If your goal is fat loss or improving body composition, this will be your guiding factor.
The next question would be when do you plan to do your training?
If you’re training early in the morning, training fasted may be more feasible. Training later in the day (after work) might make training fasted a little more difficult from a timing standpoint.
How To Determine Which Is Right For You
You may find it helpful to approach your training and nutrition as a science experiment.
This helps to remove the emotion and allow you to be more objective with your results.
If you train fasted, pay attention to your training intensity, energy levels, training duration and the amount of time since your last meal (how fasted are you).
You may find that training fasted works for certain intensity levels or workouts less than 60 minutes.
Or you may find that you perform better at 16 hours fasted versus 20 hours fasted.
If you’re fueling up before your workouts, you may find that a small bowl of oatmeal or fruit helps you perform better.
When it comes to timing, you’ll also want to see if eating 30, 60 or 90 minutes before exercise is the best decision for you.
It’s worth noting that for moderate to high intensity exercise lasting longer than 60 minutes, fed training strategies are recommended to maintain performance levels.
Whether you train fasted, fed or use both strategies, it’s important to clarify the variables to ultimately determine the best strategy for you as an individual.
Conclusion
When it comes to fat loss or maintaining lean muscle tissue, there isn’t a significant difference between training fasted or fed.
The right choice ultimately comes down to your preference and the variables associated with your training.
By viewing your training and nutrition through the lens of a science experiment, you can make educated decisions about finding the best fueling strategies for your workouts.
