Among the fitness myths that torment our lives there’s one in particular that has always been pretty popular: “ You burn more fat with low intensity exercises!”
This belief is supported by many cardio machines in gyms all around the world that gives you the option of setting up a workout labeled as “fat burning zone”. This usually refers to lower intensity, lower heart-rate zone exercises aimed to burn more fat-calories than carbs-calories.
Unfortunately this information on cardio machines is deceiving. The “fat burning zone” is a myth based on a true fact but that has been taken out of context.
In a strict scientific sense, the claim is true because training at a lower intensity requires less quick energy and as a result a higher percentage of fat is burned.
Training at higher intensity makes you use more glucose and glycogen (i.e., carbs) in proportion to fat.
By training at lower intensity, instead, you burn more fat calories BUT you burn fewer calories overall than you would if, for the same amount of time, you workout at a harder intensity.
In other words, if you’re trying to lose weight, even though a higher percentage of fat is being used, a lower amount of fat is lost.
To put it differently if you do work at low intensity, you need to increase the time spent exercising to burn more calories.
What really matters is the total number of calories burned
Just the number of fat calories you burn isn’t that important, because if you burn a lot of carb calories, these need to be replaced. And if the carb calories are not compensated with your diet, your body will need to use the fat stored and break it down into carbs.
So, even if with a high intensity exercise you’re burning more carb calories and less fat calories, your fat still inevitably gets used.
Let’s say that you have 1 hour in your day to workout: if you power-walk you’ll burn fewer calories than if you run. And if even running may cause you to burn a lower percentage of fat, since you burn overall more calories, at the end of the day you’ll still use more fat calories.
Bottom line: if you’re trying weight you should really seek to burn as many calories as possible.
The Iron You