I did a one week experiment of my own after reading this article, hitting the gym for high intensity intervals at like 7AM every morning. My writeup at the time:

http://troutgirl.tumblr.com/post/2452476550/working-out-before-breakfast

However, I have found since then that I have no problem doing pretty strenuous 8-mile bike rides before breakfast. I suspect the difference is mostly that I'm just so much happier being outside and sprinting for the traffic lights. Also the biking was more in the summer months rather than my original experiment that was in the dead of winter.

I still would not dare to lift a lot of weight without eating breakfast, but I would definitely say that cardio in a fasted state could be possible if you find an activity you really like.

Thanks for posting this.

I had heard that heart attacks are more likely in the morning so this is a good counter balance to that.

Weight before breakfast is great actually. Prefer to do it, results in better fat burning as well.

Do you ever struggle with weights before breakfast because of low blood sugar?