Now that you have what it takes to build your base, what comes next?  You’re getting the health benefits, but you want more than that!!  What do you do if your cardio workouts aren’t helping you shed fat?

Been There, Done That…

Here’s the simple truth:  remaining in the fat burning zone for workouts other than light/recovery days will not equal fat loss and fitness improvement over time.  Hey, don’t take my word for it.  Read on.  Let’s dig a little deeper.  After all, it took me 4 years of exercise physiology to get my degree and several training certifications to learn about the science behind all of this….so could the answer to maximum fat loss really be summed up by one simple equation for everyone?  I wish! 


What’s wrong with following the 220-age formula?  Why isn’t the “fat burning zone” burning your fat?

In Cardio Training 101, I DID say that moderate intensity exercise was appropriate people getting started or getting re-started – when you are building your cardio fitness foundation.  But, when the fat burning zone seems to burn more brain cells than fat cells, it’s time to move on.

Since exercise science is just that – science – things are about to get a little more complicated!  Here’s the science behind why I say that following the 220-age formula isn’t a great way to find the best training heart rate once you’re past the base-building phase.  It uses 2 pretty big assumptions:

* that exercise heart rate can be used to predict how your body uses oxygen (aka oxygen consumption or VO2 max, actually determined by using gas analyzers in a lab) and…
* that maximum heart rate is the same for everyone of a given age.

 If you just read that and now feel a little lost, think about it this way…


To get results, should a 30-year old Olympic triathlete have the same training heart rate as a 30-year old couch potato?  What about a 55 year old who has been regularly exercising for 25 years and a 55 year old who is just getting started?  Should these very different people be following the same training program?  That doesn’t make any sense!  FACT Using the 220-age formula for determining the right training zone will guarantee that some people will overtrain while others will undertrain – with neither scenario producing the desired results. 


So if it doesn’t always work, why have we been training in the fat burning zone so religiously for so long?

The fitness industry created the rule of the fat burning zone by following scientific facts, but these facts got a little “lost in translation”.  Here’s what I mean…

At a moderate intensity of exercise, a big proportion of calories burned are fat calories – this is where the love of the fat burning zone comes from!  At a high intensity of exercise, a smaller proportion of total calories burned are fat.  Stay with me, because here’s the BUT… and this is the BIG BUT!  When it comes to weight loss, it is not the proportion of each fuel (ie fat) used but the total caloric expenditure that is crucial!  If you can burn 500 calories in 20 minutes of exercise, this is more favourable than burning 350 calories in 20 minutes!  I hope this answers your question as to whether it’s best to exclusively be in the “fat burning zone” for your workout sessions.


More about the MYTH of the fat burning zone – BUSTED!
We all know that the best way to lose fat is to take in fewer calories from food (and drink) than we expend in activity.  We should also know that the higher the exercise intensity, the higher the amount of calories burned.  I’ll spare you the mathematical specifics, but consider these facts…

There are two components involved in the total calories burned in exercise.  First, there are the calories burned during the activity itself, which accounts for most of the caloric expenditure.  In addition to that, there are the calories burned after exercise.

Here’s a simple picture that sums up the whole thing using an interval workout as an example.  The red peaks are the high intensity bursts in the interval workout and the dips are the rest periods:


FACT:  After an intense workout (especially an interval training one), the metabolic rate remains elevated above resting levels.  This heightened metabolic rate is termed the EPOC, which stands for excess post-exercise oxygen consumption.  Think of it as the post-exercise fat burning zone, because the EPOC is fueled by… guess what… fat!  It is important to mention that not all exercise produces a big EPOC.  The science shows us that the higher the intensity of effort and the longer the duration, the bigger the EPOC.

FACT:  Your post-exercise fat burning zone barely exists after moderate-intensity exercise. Bye-bye bonus fat burning.   When we’ve upped the intensity of our efforts in class, I’ve often talked about the amount of calories we burn being elevated after our session is over.  This is the nuts and bolts of the science behind what I mean! 


Ok.  I’ve hit you reasonably hard with facts and now it’s time to take a break and let it all sink in…


In my next post, I’m giving you a practical tool to add to your fat burning arsenal.  After all, I basically told you not to use the 220-age formula but I didn’t tell you HOW YOU SHOULD CALCULATE YOUR HEART RATE TRAINING ZONES!  I’ll be bringing you an accurate way to find YOUR best training heart rate – whether you’re just starting out or if you’re a hard-core gym goer looking to maximize your fat loss in exercise.   Check back to the mcc blog to get this training zone calculator and you can guarantee you’re working at the intensity that’s going to produce your best fat-burning results ever!!