Q: I keep getting told that I should switch my aerobic training to first thing in the morning on an empty stomach. Is this really going to help me burn more calories or should I stick with an energy meal prior to working out?
A: I’d go with the energy meal for two reasons. Firstly, the right kind of small snack about 30 minutes prior to training will help get you primed for a productive training session. After all, it’s hardly fun to train while you’re stomach’s rumbling. More importantly, though, a high carb pre-workout snack, especially first thing in the morning, will supply the glycogen that your brain needs to function properly. The glycogen that your body needs to exercise will come from what you’ve eaten over the preceding couple of days, as it takes some time for the glycogen to make its way to the muscle cells. This glycogen, however, cannot get out of the muscle once it’s in there to be used by other parts of the body such as the brain.
Now, overnight your body still requires glycogen for brain functioning. Since you’re not eating, it gets it from the small amount (about 20 grams) of glucose circulating in your blood stream as well the glycogen that is being broken down to glucose in your liver. This supplies a minimal amount of glycogen to the brain – just enough to see it through the night. In the morning you need to start re-supplying glucose to your body in order to keep your brain functioning. Failure to do so will still keep your brain working, but it will be at the expense of your muscle. Your body will convert body protein to glucose. By stripping the nitrogen from the protein in a process known as gluconeogenesis, it transforms your muscle protein into brain food. It would be nice if the body used stored fat rather than protein to supply the brain with glucose during this time. Unfortunately, however, that’s not how our bodies work. Fat simply cannot be used to make glucose.
The concept of exercising early in the morning on an empty stomach, then, doesn’t really stack up under the evidence. You need to have a decent carbohydrate meal about 30 minutes prior to working out – not to supply energy to your working muscles, but to supply it to your brain. An easily digestible energy bar along with a cup of black coffee (hold the sugar) will do the job nicely.