It makes no sense to excercise on an empty stomach. If you're going by the calories used / calories expended it has nothing to do with metabolic advantage opinion, then you need to look at the total expended calories for the whole day.

If you burn 600 calories on an empty stomach and then eat, your body is still going to have to use up the calories in that meal throughout the day otherwise they will replace whatever "fat" was burned during the excercise. The only thing that makes excercising better than non-weight loss focused aerobic activites is that by exhausting our muscles we cause them to need more fuel to repair and grow in addition to the original expenditure of fuel needed to perform the excercises themselves.

But as we all know with LC you don't need to do ANYTHING different besides stopping the insulin induced fat storage response by limiting our carbs. We can eat twice as many calories as we ever did on a high carb diet and lose weight. It's not about the calories we eat or the calories (whether in the form of carbs or fat) that we burn. It's about correcting our body's imbalance so it can rid itself of the fat stores it doesn't need. It's the insulin that tells our body to store the calories our body doesn't immediately need as fat. By correcting our insulin response we stop that cycle.

Sorry but so many people try to just switch carbs for fat and keep all the same principles of the low-calorie mentality and it just doesn't apply to a low carb lifestyle.

In the LC life, excercise is important for whole body wellness, strengthening joints and muscles (including the heart) to prevent injury - not for calorie burning. The Cardio workout mentality is just as wrong and detrimental to us as the low-fat myths.