Although high intensity exercise has been proven, among other things, to enhance cardiovascular health and strengthen the musculoskeletal system, there is a common misunderstanding that low intensity physical activity is best if your goal is fat loss. I once had a client slow down because she did not want to go above 65% intensity and get out of her “fat burning zone.” It is true that the lower the intensity, the more the body relies on fat as its energy source. In fact, you are burning the most percentage of calories from fat while you are sleeping! At higher intensities the body shifts to using a higher percentage of calories from glucose (broken down carbohydrates).
But here’s the catch: to lose body fat you must burn more calories that you consume, period. Whether those are fat calories or not, the important thing is that you are using as much energy as possible during a workout. You don’t lose fat simply by burning more calories from fat—if it were that simple you should be able to sleep all day, burn the highest percentage of your calories from fat, and have the physique of a fitness model. If only it were that easy…
Body fat comes from excessive caloric intake, is stored on the body in a genetically determined sequence (think apple-shapes vs. pear-shapes), and serves as your body’s energy reserve. Since your body is designed to first use readily available fuel sources from the blood stream, muscle tissue, and liver, there must be a prolonged caloric deficit for your body to tap into its fat storage reserve. This happens over time, while your body is recovering from exercise, not DURING an exercise session itself.
Staying within your target heart rate range is recommended for exercise, but that recommendation is between 50 and 85% intensity, it does not peak at 65%! And depending on your fitness level and goals, performing exercises at 95% intensity may even be appropriate. As long as you are doing more than what your body is accustomed to, it will adapt and become stronger; if you don’t, it won’t!
Moderate intensity exercise is effective for maintaining health and weight, but getting out of the “fat-burning zone,” is more effective for enhancing certain aspects of fitness and, when other factors are kept constant, speeds up fat loss.
So forget the “fat burning” myth and try upping the intensity!!
