Can You Burn Fat for Energy While Lifting Weights?

Can I burn fat lifting weights?

lifting weights2Everytime I go into a gym I see someone lifting incredibly light weights, at rapid succession (while using horrible form I might add.) So the other day I went and I asked this gentleman why he was lifting a weight that was so light and his answer was; “I want to burn fat for energy.”

So I thought back to the 20 plus years I have had in the fitness industry and there was not a day that went by that a client or a member of my training center asked me; “Can i burn fat lifting weights?”  I wish the answer was a simple yes or no, but it really isn’t.  Instead of giving them my thesis paper all over again, I thought I’d write it here.


First and foremost, let me state that the body has three energy systems constantly working albeit in different ratios and proportions based upon the intensity of the exercise and the duration of said exercise. The three systems are ATP-CP system (the energy that exists right in the cell), the Anaerobic Glycolytic System (breaking down carbs for energy), and the Beta Oxidation system (Fat Metabolism.)


atpcpsystemATP -CP System this system is used primarily for quick energy. It is energy that resides and exists right in the mitochondria (the power house of the cell.)  This is high intensity and fast acting, however it is very limited for its duration 0-30 seconds best for this one.  Great out of the gate, but no staying power.  Because of its quick nature this one really doesn’t burn fat.  When the body is looking to burn fat for energy it takes time. There just isn’t enough time in this energy system.



anaerobic glycolysis.jpg

Anaerobic glycolytic System– this system breaks down carbs into energy by a multiple step process that enables the body to enter into the Krebs cycle or the Corey cycle, depending upon whether there is oxygen or enough oxygen present during the exercise.  This is the system along with the ATP-CP system that is primarily used during resistance training.  The body uses carbs and the storage form (glycogen) to produce energy while lifting weights.  It is quick hitting, quick acting and is able to be used without the presence of oxygen.  Remember resistance training is anaerobic in nature (meaning it is without oxygen.) So although I know you don’t want to hear this; “This energy system doesn’t burn fat for energy much during the activity either.”






betaBeta oxidation system– this is the system that breaks down triglycerides to produce energy.  This system is for activities of a continuous rhythmic nature and this system does not kick in significantly until 16 minutes or greater.  The triglycerides must have two things present in order to be chemically cleaved so they can be used for energy. Those two things are water and oxygen.  First the fat molecule must be hydrolyzed, and then it must be oxidized.  Let me give you an easier to understand illustration: If you were going to start a fire in a fireplace you wouldn’t just hold a match under a log and expect it to catch fire.  You need kindling under that (maybe some newspaper or some wood chips) as the match hits the kindling it catches fire then ultimately the kindling catches the logs on fire.  Same thing with fat metabolism – the oxygen is the kindling.  If you have no oxygen you can’t break down the fat molecules.


Now, indirectly you do burn fat with resistance training due to the fact that the more increased muscle you have, the more calories you burn even at rest.  However, during the resistance training session itself, you use almost exclusively, carbohydrates as energy to perform the exercises.  So in the end, in order to most effectively change your body into the body of your dreams (or your girl’s dreams, if you are a guy) you should allow resistance training to play the role that it is meant to do.  Resistance Training’s role is to deplete muscle glycogen stores and break down the contractile proteins in the muscle so they must rebuild stronger and more dense.  In addition to this, when the body resynthesizes the energy stores that were depleted by lifting weights, it takes energy and that energy comes from (drumroll please) you guessed it; Fatty Acids.  So, if we are lifting weights we will indirectly burn fat for energy, but not until AFTER the lifting session when we are outside of the gym and we are repairing and restoring our body for the next round.


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