Your biorythm is highly affected by hormones. If you have a ton of hormones in your system that wants to put you to sleep, odds are slim you're in shape to drive off to the gym and do any record squats. In other words, it's the flip side of the coin that makes it hard to relax and fall asleep during the day, when you'd normally be up and doing other things. Your body don't like to change things around too much.
With this in mind, I hope it's obvious why there is no "one-size-fits-all" solution. However, there are a couple of general rules that applies across the board.
As you strive towards your fitness goals, there are a few prime objectives that has to be observed at all times. It's tempting to "forget" this when things get inconvenient, but the joke is on you - No one but yourself suffers if you waste a pound of hard-earned muscle mass by dropping the ball.
- Keep the muscle you have!
- Stay fueled to get the most out of your workouts!
- Get in tune with your biorythm!
...In plain English, this means: Eat properly before attempting morning training (depending on the type of training you plan to do - more about this later), and not to fight your body's natural peaks and lows, strength-wise. Not only will you be less energized if you try to do some heavy lifting when in a "low" state, but you'll also be more likely to injure yourself.
Ok, so you've decided to take the advice about doing some morning cardio to get rid of the lovehandles and look really buffed and awesome for the beach in June... Or perhaps you just don't like the way the jelly rolls bounce when you run without a shirt on. Either way, this is THE time to get some fat burn going. As you haven't had any major meals for several hours, there's very little carbs floating around in your system that can be used as fuel instead of bodyfat. Bad news is, as there's little carbs around, the body doesn't mind cannibalizing some muscle mass along with the bodyfat. Yikes! Frontal assault on objective one!
The task here is to spare the muscle, and further stimulate bodyfat to be used to fuel the workout. The first part is solved by gulping down a protein drink with at least 40 grams of high-quality protein (preferably Whey, which is high in L-Glutamine). This way, the inevitable lost protein is taken from your bloodstream, not your biceps (keep in mind that muscle IS protein!).
The second part can be done a couple of different ways. First off, drink plenty of water!! Water is an absolute necessity to make this happen! Secondly, pop a couple of fish oil or flax seed oil capsules. Getting a couple of grams of "good" fats can help jump start the fat burning process in your body. Also, if approved by your physician, caffeine/ephedrine-based fat burners can do wonders in both releasing stored bodyfat into the bloodstream, AND crank up your metabolism to burn even more calories.
As for the timing, try to get your protein drink, fish oil, and fat-burn pills into your system about an hour before the workout. In other words, it's a good strategy to do this first thing as you wake up, and then do the normal morning chores until it's time to head for the gym. 45 minutes is the bare minimum you want to allow for the nutrients to enter your bloodstream. Avoid carbs like the plague - until immediately after the workout. Then you'll benefit from 100 grams or so of something sugary, like a couple of bananas or a classic coke (!).
Morning Weight Training
The objective here is to get your overall energy levels up ASAP. You'll need plenty of fuel readily available in your bloodstream to make sure you can pull off a heavy session with the barbells. In other words, you have the very opposite situation as above, where you strived to keep energy levels DOWN.
First thing when you wake up, is to eat something that'll give you a good load of carbs and protein. Oatmeal porridge, egg whites, a fruit, a glass of juice, and a glass of low-fat milk is THE power breakfast. Give yourself a variation of fast and slow carbs, and don't forget to get some good fats in there as well. Allow for at least an hour to digest this food. You don't want to go to the gym and find that your body is still busy trying to digest the breakfast.
One thing the Weight Training shares with the Cardio, is the need for fast carbs (sugar!) immediately after the training. Remember - after a workout, your muscles are in a state of catabolism, and the only thing to save them from getting cannibalized is to feed the body something else to eat instead of your own muscles. And it has to be fast!
Wrapping It All Up
Simply put, there is no right or wrong here. If you can handle morning weight training, more power to you. I can't touch the weights until noon or so, simply because I don't feel like I've had time to store up enough energy to get a productive workout. I know others who feel "burnt out" after work, and would never be able to work out anytime BUT in the morning!
One thing I'd like to point out though, is that it is close to impossible to combine the two kinds of morning training in one session, with good results. If you do the "cardio breakfast", you'll burn fat alright, but when you try to hit the weights you'll not be as strong as you could be, while sacrificing muscle mass for no reason. Likewise, a "weight training breakfast" will make the weight training part work fine, but when you step onto the treadmill (or whatever), you will burn mostly carbs (in your bloodstream), and very little bodyfat. In addition, by eating carbs, you'll probably have triggered a release of Insulin, which in turn seriously hampers your ability to burn fat for hours afterwards.
Conclusion: Pick one, don't mix it up. Designate different days to different types of morning training.