The first misconception is that performing low intensity exercise will put you in the fat burning zone and is therefore the way to go if fat loss is your goal.
You see it all the time on treadmills and ellipticals labeled as the fat burning zone, literally.
The logic is, If I stay in this zone long enough, Ill reduce all my fat.
Its a good way to sell cardio equipment, but not necessarily the most efficient way to reach your fat loss goalsand heres why
First, lets define low-intensity exercise which is any exercise that requires less than 40% of your VO2 Max.
Okay, what does that mean?
Simply put, if you are able to exercise and speak comfortably, its considered low-intensity.
The Science Of Low Intensity Workouts
Now lets get into the science behind it all.
The metabolism of fat during exercise is a complicated process regulated by multiple hormones.
Generally speaking, as exercise intensity increases, our usage of fat for energy peaks and then actually decreases.
Much of the confusion regrading the optimal intensity to burn the maximum amount of fat comes from understanding and applying the non-protein caloric equivalents for respiratory quotient. Right about now, youre probably saying to yourself, what the hell is that? This basically tells us what percentage of fat and carbs our bodies are using for energy based on oxygen consumption.
The point of the matter is, we need to shift our mindset from trying to find and stay in the fat burning zone and focus on energy expenditure.
At the end of the day, a calorie is a calorie no matter where it comes from. Consistently burn more of them and the fat will begin to disappear.
Now if this looks like a different language to you, thats okay, well get to the point shortly.
At a respiratory quotient (RQ) of 0.83 (meaning relatively low-intensity exercise), the percentage of total calories from fat and carbohydrates are 56.2% and 43.8% respectively. So from this initial assessment, believers in this misconception would be correct BUT, this is only from a PERCENTAGE standpoint. The problem is, at lower intensities, the calories burned is ultimately lower as well meaning the total AMOUNT of fat burned is also lower.
Remember, in order to burn more fat you need to burn more calories, so does the percentage of where these calories are coming from, fat or carbs, really matter?
In order to burn a larger amount of fat, we need to burn more calories. In order to burn more calories, we need to work hard and to work harder means a higher intensity.