“WHOA WHOA WHOA ladies and gentleman slow down on those treadmills!” “Don’t you know that going so fast only burns carbohydrates and not fat!?!” “You need to slow down and get into your fat burning zones!!” While working out at Lifetime Fitness in Rochester Hills I heard this statement multiple times from trainers and fellow exercisers. They also had charts posted on treadmills that told you what heart rate zone you needed to be in to MAXIMIZE fat loss. At AFS I am often asked by new clients what heart rate monitor I recommend so they can stay within their optimal range during class. In this blog I will show you these zones DO exist, just not in the way that some trainers and exercise equipment manufacturers have convinced you they exist.
What Matters Most?
Let’s get one thing clear; it is true that certain intensities burn a higher percentage of calories from fat. However, this does not translate into more absolute fat at the end of the day. During various intensities of exercise the body shifts between the use of fat, carbohydrate, and protein as fuel. While at some intensity levels you do indeed burn a higher amount of fat, you burn CONSIDERABLY fewer calories. When we look at fat loss, calories are all that really matter. The reason is that the larger calorie deficit you can create during exercise the more fat your body needs to use at REST (90% of your day).
Let’s compare two different exercise intensity levels and the calories expended by a 130lb woman. When training at a high intensity (85% of max heart rate) for one hour, 918 calories are expended, 230 of those from fat. When training at a lower intensity (65% of max heart rate) for one hour, 585 calories are expended, 292 of those from fat.
While you burn 62 more calories from fat during exercise in the low intensity “fat burning zone” the additional 333 calories you burn during high intensity exercise will result in an additional 1 pound of fat loss every 11 days compared to the low intensity exercise.
Is Cardio Necessary For Fat Loss?
Now that we took care of the zones, lets dive a little deeper into this topic of cardio and fat loss… IS CARDIO EVEN NECESSARY FOR FAT LOSS??? Simply put, NO! One important thing to remember is exercise is NOT intended for fat loss. Exercise is intended for some type of physiological adaption whether it’s muscular strength, muscular endurance, cardiovascular endurance, power etc… With that being said, one beneficial byproduct of exercise is that it can aid in providing your body with a significant calorie deficit without extreme dieting (in addition to other health benefits). However, if you eat too much food (creating a calorie surplus) you can exercise 7 days per week 3 hours per day and you will still GAIN FAT!!! For this reason, food logging is still the king for fat loss and the most important zone to be in.
Where Do You Go From Here?
If you want to lose fat you need to be in a calorie deficit. In order to be in a deficit, the vast majority of individuals must food log. If you want to restrict less and compliment your dietary deficit with an exercise induced deficit (which has been proven in research to be the most effective approach) be sure to work out as INTENSELY as possible for whatever duration of time you are able to devote to exercise. Still not sure what to do? Check out my article on HIIT to learn about a training method that’s currently making waves in the fitness industry.