If your looking to lose weight then it's simple. Burn more 'calories' than you consume. The harder you work the more calories you burn. But these calories at higher intensities are scourced from glycogen (carbohydrates and sugars).
If it's fat that your looking to burn then it's entirely different.
In order to get lean body tissue you have to train at lower intensities for longer periods to maximise fat metabolism. This 'easy' work mixed with the right amount of strength and speed work will maximise your fat metabolism further still when training AND at rest! This in turn will improve your power to weight ration. Get the training intensities wrong and you risk injury, stiff and sore musles and the possibility and worse case scenario of losing fitness!
Here is a simple guide and based on the results my fitness testing business 'Trainsmart' has seen in testing over 200 road/mountain cyclists/ triathletes/ runners and non sport related individuals.
At your optimum fat burning zone you use approximately 30-60% of your energy from fat (slow release energy) and 30-80% from carbohydrates and sugars (quick release energy).
At around your endurance intensity that reduces to approx. 10-35% from fat and 65-90% carbs and sugars.
At higher intensities of Anaerobic threshold or higher (race pace over shorter distances) you source all your energy from carbs and sugars only and no longer fat burn!
So when you run out of carbs/sugars you will 'bonk' or 'hit the wall' etc...
Consider that you lose approx. 500-1000calories an hour and you will soon run out of energy if you train too hard all the time!
Your body has around 30-40'000 fat calories available for fuel as energy.
But only 2500-4500 calories available from carbs and sugars!
So you have approx. 10 times the available energy from fats!
Train your body to source fat for fuel properly and you not only will go longer without fatiguing but also go faster, recover quicker and be able to do harder sessions more frquently!
This is how Lance Armstrong has enabled himself to recover quicker between stages over the other riders and have more fuel available to his working muscles so he can ride harder, stronger, faster and further than most! He is not necessarily 'fitter' than the other Tour contenders just more efficient at how his body uses fuel etc...
I hate to disagree with you here when you're citing lance in your post but I will just put another idea across here as we're talking about fat loss and it's in a training discussion forum
To say that there is one and only one way to burn fact is incorrect. Scientific research has in fact proven other methods to be more effective than the traditional "fat burning" train of though.
A key point that was missed in the previous post is that it's not the type of tissue that you burn whilst training, it's more the effect in terms of overall calorie consumption and the increase in your metabolism.
Interval training has been proven more effective at reducing body fat in numerous scientific papers