Q: What does calorie deficit mean? How does it affect the body when exercising?

A: Calorie or caloric deficit is just a fancy way of saying that you're eating fewer calories than you're burning every day. This means that you are losing weight as your body uses up internal fat reserves and muscle mass for energy. In almost all cases, your goal while under caloric deficit is to structure your diet and your exercise programs in such a way as to maximize the use of fat for energy and minimize the use of muscle for energy. This way you'll spare the most muscle and burn the most fat. How to structure your diet and exercise programs this way is what this site is all about! Check out http://www.mikesfitness.com/content/lists/articles if you haven't done so already.