How can I burn fat??

This is a question most people want to know the answer to, so I sat down with a sports nutrition book, my old anatomy and physiology textbook and the text I’m currently teaching from.  The answer is not simple, and it depends on factors such as energy needs of the moment, availability of oxygen and carbohydrate and body composition, to name a few.

Fat needs oxygen (O2) and carbohydrate (CHO) in order to burn as energy.  It is important to know that the metabolic process by which we glean ATP (units of energy we use to move) that fat goes through takes a lot of time but yields ALOT of ATP.  Metabolizing CHO is much faster, but doesn’t yield as much ATP.  It is also important to know that body fat is the preferred source of muscle tissue at rest–the more muscle tissue you have, the more fat you will burn just sitting around doing nothing.  Remember though, that the more time you spend sitting around doing nothing, the less muscle you have, generally speaking…so let’s talk about the fuel we use at different levels of exercise intensity.

If I’m sitting around doing nothing, I’m burning mostly fat.  If I get off the couch and head out for a walk with Otto and I can sing to him, this is the lowest level of intensity, and I’m burning a mixture of fat and CHO, mostly fat.  If I pick up the pace and can talk comfortably to Otto, but can’t really sing as easily, I’m still burning a mix of fat and CHO, but the amount of fat I’m burning is starting to decrease, and the amount of CHO I’m burning is starting to increase.  The faster I go, the higher the demand is for ATP right NOW and my body switches to more CHO and less fat being used as fuel.

Once Otto and I are going so fast that I can’t even talk, and I’m breathing pretty hard, I’ve crossed over into anaerobic respiration.  What that means is that since there isn’t any O2 available, I’m not using fat as fuel, just CHO since that can burn without O2 and I really need energy QUICKLY.  You might be wondering why in the world I would cross over into a form of respiration that doesn’t use fat as a fuel source if my goal is to burn fat???  The more I cross over into anaerobic respiration, the more I increase my O2 carrying capacity, which means that the next time I work out with Otto, I can stay longer in aerobic respiration or “fat burning mode”.