Does working out in a fasted state cause adrenals to release cortisol?
Yes, working out in a fasting state can cause your adrenals to release cortisol and epinephrine....but EVERY SINGLE TYPE OF WORKOUT causes your adrenals to release cortisol! Which is not inherently a bad thing.
FIRST...WHAT IS FASTED?
Fasted cardio refers to doing a cardio workout before eating anything in the morning (AKA at least 6 to 8 hours after eating).
It is up for debate on whether or not coffee or pre-workout counts as fasted! In my humblest of opinions, pre-workout and black coffee do not count as "eating" or a meal. With that said, I strongly feel consuming coffee before a meal detrimental to the gut lining!
STRESS RESPONSES
When you exercise, your body requires energy to fuel the activity, and if you haven't eaten in a while, your body may turn to stored energy sources such as glycogen and fat to provide the necessary fuel.
This can trigger a stress response in your body, which can cause the release of cortisol and epinephrine from your adrenal glands.
PROS & CONS
Cortisol is a hormone that helps regulate your body's response to stress and can increase glucose production in your liver, which can help provide energy during exercise. However, if cortisol levels remain elevated for an extended period, it can have negative effects on your health, such as suppressing your immune system and increasing the risk of chronic diseases.
Similarly, epinephrine is a hormone that can also be released during exercise in a fasted state. It can increase heart rate, blood pressure, and breathing rate to help deliver more oxygen and nutrients to your muscles during exercise.
Regarding fat oxidation, "there also is evidence that consistent exercise while fasted results in chronic molecular adaptations favorable to fat oxidation. For example, 6 weeks of fasted aerobic training increased the content of intramuscular fatty acid binding protein and uncoupling-protein-3 content to a greater extent than training post-prandially".
CARDIO SPECIFICALLY
Doing fasted cardio isn’t going to burn more body fat than performing cardio in the fed state. What will lead to greater fat loss is when your cardio creates a caloric deficit.
Doing fasted cardio may have other positive metabolic outcomes that may be beneficial to specific populations (i.e. obese, pre-diabetic/diabetic individuals).
So depending on your personal preferences, lifestyle, and what may be more convenient to you, either approach to cardio may be included into your exercise routine.
TO WRAP UP
Despite several research studies showing that during low intensity exercise in the fasted state, the amount of circulating free fatty acids were greater, this does NOT mean more fat is lost (Escalante et al., 2020, Vincente-Salar et al., 2015).
While exercising in a fasted state can have some benefits, such as potentially increasing fat burning and improving insulin sensitivity, it may not be suitable for everyone, particularly if you have underlying health conditions or are prone to low blood sugar levels. It is important to listen to your body and consult with a healthcare professional before making any changes to your exercise or dietary habits.
