With anything related to fitness, there's no right or wrong answer here. The idea of doing fasted cardio came about as a "fat-loss hack" but does it really work? I tried both and these are my findings.
(Keep in mind that once again everybody's body is different - do what works and what feels good for you. There's no right or wrong answer and when it comes to fat loss, there's more than one way to skin a cat shall we say. )
FASTED CARDIO - WHAT IS IT AND WHY WOULD I DO IT?
Fasted cardio is when you perform cardio after a prolonged period of not eating (usually in the morning). To be in a "fasted" state your body would have either a) had its last meal several hours ago (usually 8-12) OR your body has completely run out of "glycogen" or the sugar from carbs that your body uses for fuel. Your body prefers to run on carbs for energy - but when your body completely runs out, your body is forced to run on body fat instead. Hence the trend to train fasted.
In general exercise, it usually takes between 15 min and half an hour to burn through all of your glycogen before you start burning fat. Most people don't work out past the 30-minute mark, so essentially you're burning off what you ate instead of actual fat. This is why training fasted has become so popular.
FED CARDIO - WHAT IS IT AND WHY WOULD I DO IT?
Fed cardio is when you eat a carb and protein-rich meal (or any meal really ) 30 to 60 minutes before your workout.
The benefit of this means that the protein in the meal will help with muscle building and recovery as you exercise and the carbs will give you enough energy to get through a fantastic workout. If you're eating 30-60 minutes before a work out generally speaking you should have enough energy from the meal itself to go past the 30-minute mark (depending on the style of workout).
SO THEN IF THEY'RE BOTH GOOD, WHICH ONE SHOULD I DO?
As previously mentioned, there's more than one way to skin a cat and there are pros and cons to both. Let's talk about my experience.
I walk or run first thing every morning. I run 5-6km two days a week and the rest of the week I walk the same distance in the mornings. I tried running on a full stomach (having breakfast 30 min before my run) and I felt completely sick and thought I was going to throw up. I like feeling light when I run, so having a full stomach or a full bowel is a no from me. That being said, I like to make sure I have some fuel in the tank before I train with weights. If I have no food in my stomach and then start lifting, I feel dizzy and can't complete the workout.
What does that leave you with?
Experiment with both and experiment with different workouts to see what feels right for you. At the end of the day, it makes no sense to train fasted if you don't have enough energy to complete the workout. When you're working out with a specific goal in mind rather than just for health reasons, you need to be putting together a regime that's sustainable. If you can't complete the workout because you're burnt out, that's not sustainable.
Something else to note is that regardless of whether or not you train fasted, your body needs fuel at SOME point. Most likely you will eat back the calories you burned during your food free workout. Which in some instances is fine - because your body needs calories. Eating your calories back only becomes an issue when you need to be in a calorie deficit because you're on a fat loss regime. If you're building muscle you need to eat more than you normally would.
1. Experiment with different workouts that are both fasted or fed. You'll quickly realise what works for you and what doesn't.
2. Stick to what's sustainable.
3. If your goal is fat loss, it ultimately doesn't matter whether or not you train fasted as long as you're staying within your correct calorie deficit.
4. If you're training to build muscle, I wouldn't recommend training fasted as you don't want to be in a catabolic state (where your body eats away at your muscle) and you need to be in a calorie surplus anyway.
And finally, DO WORKOUTS YOU LOVE! xoxo