Searching the internet for “best way to burn fat” or “burning fat vs carbs” will inevitably lead you to someone talking about the Fat Burning Zone. The concept is that there is an ideal heart rate at which you should be exercising to prioritize losing fat. How true is this?
Our bodies get the energy to move our muscles from many different sources, from the sugar currently in our bloodstream to the stores in our organs to the fat deposits all over. Your metabolism in any given moment determines which source is utilized, and the best method for measuring your instantaneous metabolic rate is your heart rate.
It is true that the lower your heart rate is, the more calories you burn specifically from fat stores. Often you see this information distilled down into a chart like this:
When I look at this chart, the first thing I notice is that we apparently burn a lot of fat when we’re just sitting on the couch! I bring this up because you intuitively know that this is not the path to physical fitness.
The second thing I notice is the prominent “Fat Burning Zone,” which this article defined as 60-70% of your max heart rate. When you work in this range, you will pull more than half of your energy from your fat stores. Sounds appealing on the surface right? But this is misleading to only consider where the energy is coming from. We also need to know how much.
The fact is, the harder you workout, the more calories you burn in total. Even if a smaller percentage of that energy is coming from fat, you are still doing more work. I like this chart in conjunction with the other one:
While all of these charts are an over-simplified explanation of our metabolism, this makes it much clearer that the fat burn is still happening.
What does this mean at Progress?
When I find any fitness tip that seems like a quick fix, my Category 5 skeptic alarm goes off. I know we all want a fast solution to every problem in life, but deep down you know that the harder you work, the more change you will effect.
This is why sessions at Progress are designed to keep your heart rate elevated, even when we are lifting weights. As you move through the exercises in a circuit, some muscle groups are working and some are resting, but by having very little down-time overall we keep your metabolism elevated. This is our efficient approach to developing your strength while also achieving a high calorie burn.
As usual, the best recommendation is to work as hard as you can! Tracking your heart rate is a great way to gauge your intensity, but your own intuition is an excellent tool as well. You know when you are pushing your body to its uncomfortable limits, and that is exactly where growth occurs!