I concur with Matt...and, in fact, I think it was Matt who sent me in the right direction that by eating/fueling properly, you'll get more out of your workout and are better-off in the long run.
The argument goes: when you first wake-up, your blood-sugars are low...so it rather makes sense that by doing cardio you'll sooner get your body into the fat-burning mode and you'll not have to spend the theoretical 20 minutes burning-up the blood sugars before your body starts burning fat....so for years we were told to wake-up and get into your routine w/o eating.
When I do this, I can do it...but I feel weak sooner and it just feels like I'm running on an empty tank.
Enter new theory: FAT BURNS IN A CARBOHYDRATE FLAME.....yep; your body needs a bit of carbs in order to facilitate the oxidation and burning of fat.
Theory this, theory that....find what works for you.
What I noticed is that I was more powerful and had better endurance throughout my workout when I had a proper
breakfast of at least 300 calories....but, I'm then going on long bike rides or working out to the tune of 1,200 to 2,000 calories. Nowadays I tend to bring a bottle of protein shake with some fruit-juices blended in...I drink a bit of this periodically as I go, just depends on my routine.
But here is something relevant....by consuming that 300 calories for
breakfast, I noticed more power, speed and overall performance in my workouts....and by wearing a heart-rate monitor that counts calories, I found that I burned MUCH more during my pre-fed workouts then my non-fed workouts! Yep, by eating 300 calories I found I had worked-out to the tune of about 450 MORE calories burnt then had I not eaten, plus the higher energy let me do some
HIIT and burst which lend towards EPOC and other thermogenic post-exercise benefits as welll.
ANYWAYS.....yes: eat. In the end you should find a nourished workout is better then a non or light-nourished workout. At the end of the week, it's calories in vs. calories out. As one person on this forum says: train hard, eat hard. Eating before, a bit during and immediately after exercise is good timing....eating too much and eating the wrong things are the problem, not so much when you eat.
Hope that helps....