If you have ever read anything about fat loss, ever, in your entire life, you have come across glowing reviews of fasted cardio. It has been alleged that fasted cardio will help you dip into your fat stores for fuel, since your glycogen levels are depleted, etc., etc. This study says otherwise.

This study flies against conventional online wisdom, but I have a feeling it is something all professional coaches know. We know that carbs are a more readily available fuel source than fat stores and that carb intake during exercise helps promote glucose uptake and permits greater energy expenditures. Since fat is not as readily available, it would make sense to me that some muscle is broken down during fasted training. Again, the body needs fuel NOW and is not going to be too choosy about where it comes from.

When I was dieting in '08, I did a lot of training on a near-empty stomach, often at the end of the workday. I couldn't lift for shit and my numbers steadily declined. I just didn't have the energy. Towards the end of my summer internship, I started drinking a protein shake prior to working out. The difference was noticeable. I should also mention that I was never carb depleted during this time.

We also know that working out in ketosis is miserable and no real work gets done. I think, knowing what we know about carb cycling, that the answer is clearly to up your carbs sufficiently in advance of your workout to permit max effort. Since we know carb intake will have a positive effect on exercise tempo, energy expenditure, and exercise length, I would expect that someone with sufficient carbs and calories in their system could workout harder and for longer than their carb-depleted counterpart. Accordingly, I would be surprised if this level of intensity didn't promote greater fat loss than the shorter, weaker exercise session of the carb and calorie depleted trainee.

The problem with nutritional science is that conventional wisdom is subject to frequent revisions and any number of people can take wildly differing approaches and reach similar results. In regards to exercise science, there appear to be a few golden rules: (1) lift progressively heavier things; (2) do high intensity cardio, preferably intervals; (3) eat roughly 1g of protein per pound of bodyweight when trying to add muscle; (4) sleep at least 8 hours a night; (5) eat carbs and protein after you workout; (6) train the big lifts; (7) train consistently and for an extended period of time, meaning at the very minimum 3 months; (8) eat fewer calories than you use when trying to lose weight, eat more than you use when trying to gain weight. These things work, every time, they just aren't that sexy.