A new study in The Journal of Nutrition shows that what you eat beforehand could affect the calorie burn during your workout. Women who ate a breakfast high in low-glycemic index carbs (whole grain breads, low-fat yogurt or non-instant oatmeal, for example) burned 50 percent more fat in a post-breakfast workout than those who ate a breakfast of high-glycemic index carbs (cornflakes, white bread or waffles, for example.)

Participants ate either a high- or the low-glycemic index breakfast, and then walked on a treadmill for 60 minutes three hours later. Blood samples determined a 50 percent difference in the amount of fat burned between the two groups. High glycemic-index carbs tend to cause a spike in blood sugar. Researchers theorize that eating a meal rich in lower glycemic-index carbs may boost the body's use of its resources for fat burning instead of blood sugar.

So what does this mean for you? First, it's important to note that this study was done on women of normal weight, not women trying to lose weight. But the researchers theorize that the results could also apply to those who have a weight loss goal. I feel that when it comes to weight loss, what really matters is the total number of calories you're burning, not necessarily where they are coming from (fat, glycogen, etc.) So I wonder whether or not it's going to affect your weight loss progress if you burn more fat.

I think the strategy used in this study could work well if you're not going to exercise for a while after your meal. But if you're like me, you'll need to eat something within an hour or so before working out or you'll start to feel lightheaded. In that case, I tend to eat higher glycemic-index foods that give me the immediate boost of energy I'll need.

In the end, I think it's important to experiment and figure out what's going to work best for you. What foods give you the energy you need to complete your workout? How long do you wait to exercise after eating a meal or snack? What do you think about this study?