There are a ton of opinions on the internet regarding this topic. The theory is that since you have not eaten anything for a while, your body is low on glycogen and thus has no other option but to dig in to your fat stores for energy to fuel your workouts. A lot of bodybuilders and athletes swear by fasted cardio but does it really burn more fat?
The latest research seems to show that there really is no difference whether you perform your cardio on an empty stomach or in a fed state. The amount of fat lost depends directly on the number of calories burnt overall and not the source of the fuel. It all comes down to calories in vs calories out in the end and whether you eat before your workouts or not does not matter. It’s all down to personal preference. If your workout better on an empty stomach, go for it. If not, have a light meal or a shake at least an hour before your workout.
Some of us find that the morning is the best time to work out since after work, we can get lazy and find a ton of excuses to ignore our workouts. You can get your workout out of the way by doing it early morning and then be at ease for the rest of the day.
In this case, it is good for you to work out on an empty stomach as you would not want to work out immediately after consuming breakfast. You need to give it at least an hour for your food to digest.
However, it is important to note that there is a higher chance for your body to go in to a catabolic state (muscle burning) when working out in a fasted state so make sure to keep your workouts under an hour. You could also choose to sip on a BCAA drink during your workouts to prevent catabolism.
On the other hand, if your workout in a fed state (1-2 hours after food), you will have more energy during your workouts and as a result, will work out harder, ultimately resulting in a higher calorie burn as compared to a half assed approach in a fasted state.
Personally, I would recommend a protein shake an hour before a workout as this will provide you with a decent amount of energy to fuel your workouts and enough amino acids to help prevent muscle catabolism and help with recovery.