Thanks for the feedback on my fat burning zone article.
It’s true if you are carbohydrate deficient that you will begin to metabolise muscle tissue. If you are depleted in carbs and are performing a high intensity cardio session working aerobically, fat is not able to supply a sustainable energy source, simply because fat is metabolised quite slowly. Muscle tissue on the other hand is utilised far more effectively than adipose (or fat) tissue.
The key with high intensity cardio is to ensure that you do obtain adequate carbohydrates prior to your training session. A big mistake is to perform this cardio on an empty stomach first thing in the morning for this very reason – you will be carbohydrate deficient. It is also unwise to perform high intensity training when you are following a particularly low carbohydrate diet – you will most likely lose significant amounts of muscle tissue.
Hope this helps mate. Carbs are so very important when losing weight. They have received a very negative “stigma” in the past decade, but this is really due to fad dieting myths rather than sound scientific research.