Fun & Fitness over 50

I just heard about this from Jon Benson who wrote a book "Fit Over 40" which I promote (see recommended eBooks in the left hand column). I signed up for his free 10 day email "Fat Burning Tips" course which includes a lot of other intriguing exercise and nutrition ideas.
Anyhow this is the gist of the concept: After you go to bed at night, you are fasting (hopefully you don't eat while sleep walking) and your body is therefore in fat burning mode. After you get up in the morning, do a cardio workout before eating anything and you will be burning primarily fat. More so than at any other time of day.
Additionally, Benson suggests having a cup of coffee before your cardio workout as this will burn fat even more by increasing thermogenic effect (internal body heat).
The workout should not be too intense (I like that part), only 65-75% of your maximum heart rate (MHR) so that you don't consume muscle (muscle wasting). He also recommends taking 5 grams of L-Glutamine powder (an essential amino acid) to further protect against muscle loss.
Why I found this especially intriguing is that I'm already doing this by default. Here's my morning routine (and I love it!):
Stage 1: get up, pee, weigh myself, start coffee (we use a one cup at a time maker) and flop down on the couch and try to go back to sleep.
Stage 2: coffee maker sputtering wakes me up, wait 2 or 3 minutes for coffee to finish dripping, fix coffee, sit back down on the couch, propped up on some pillows, eyes closed and sip the coffee.
Stage 3: Finish coffee one, fix coffee 2 if time permits.
Go to the gym or bike ride, weather and light permitting.
So, except for the L-Glutamine, I've been doing this for years.
Now, even Benson admits, fasting cardio has been a subject of controversy and continues to be to this day. However, he believes in it.
I did a little Google research myself to see what other people are saying about it and what the cons are. The major objections that I read were about the potential muscle loss. No one was saying that increased fat burning didn't happen but just were concerned about catabolic muscle wasting. Also many who had this objection stated that consuming protein or an amino acid like L-Glutamine before the workout would probably mitigate the catabolic effect.
The best advice I read about this technique was to carefully measure your progress to see if it was working for you. This would involve tracking your percent body fat. A little tricky and perhaps a subject for another post!
I will continue to do "fasting cardio" because I like doing it that way. Now I have a name for it!