Step into a gym, have a session with a PT or hook yourself up to a treadmill and you’ll be touted that the best way for you to shift that excess blubber is to crack on in the moderate or amber zone, because this is the “fat burn zone”. Day in day out, Slimming World’s finest turn up for a boring hour on the cross-trainer in the hope that training in this magical heart rate zone will mean their fat dissolves before their eyes and their next weigh in will be all lean muscle.
So why are people rocking up to the gym, following this exercise protocol and not seeing results? Is the fat burn zone simply a myth, or is it the participants aren’t using it correctly? If it’s all guff, where did it all come from?
What is the fat burn zone?
The fat burn zone is usually used as another term for the aerobic exercise range of heart rate. This essentially means it’s an exercise intensity where the type of fuel used is fat. The other possible energy systems or zones we could be in, are those employing the immediate energy stores in the muscles for very quick bouts of exercise like a quick sprint up the stairs (but these stores are extremely sparse) and anaerobic zones where we are exercising at a higher intensity and relying more on our carbohydrate stores (also known as glycogen) to carry out exercise. Energy systems aren’t quite that simplistic, but for the sake of this article, that’s enough detail so your brains don’t get blown out just yet, I need you to make it to the end.
When we use energy pathways that allow us to workout more intensively, the trade off is that we cannot utilise those systems for very long. Endurance athletes often worship the fat burning aerobic zone for this reason because it allows them to go a very long way for a very long time, though not as quick as someone running a very fast but short race.
In order to try and help us train and get the best from ourselves at various intensities and distances, athletes use hear rate zones to work out what type of pathway they are using and try and train the ones they need to. Unfortunately, while we often present people with a fixed range written on the treadmill, we know that it’s not that simple and there will be masses of variation from person to person. There’s also no black and white to this; you won’t suddenly ONLY be using fat or ONLY be using carbohydrate and you won’t use one type of energy during one workout, you are likely to move through several different pathways. So it’s all a bit more complex to even access this fat zone, let alone harness any advantages it might have.
All that said, on the other, hand, we often don’t consider how much time we naturally spend in the fat burning zone in our day to day lives; anything low intensity, could be utilising our aerobic system. The daily dog walk, the housework, just living! If we fuel our bodies the right way, we enable it to utilise this fat burning zone throughout the whole day. But that’s the key – IF we fuel our bodies the right way.
Fat is not actually an easy resource to access, nor is the stored carbohydrate in our body. Our bodies are very efficient and they will always use preferentially, what is available more freely. That means, if you’re spending the whole time filling your body with high GI foods which are easily available fuel, your body will live off that, because it’s easy. So there is a fat burning zone of exercise, but there’s also the opportunity to be living off fat when we’re NOT exercising. Both of these, are only accessible when we pay attention to our diet and intensity of our exercise.
So if I want to lose fat, then I should exercise in the fat burn zone?
If we look at the European guidelines for obesity management, aerobic exercise is cited as the go-to exercise method. Why? Because obese individuals who are not training regularly are more likely to comply with this programme. We also know that for overweight individuals, doing exercise at lower intensity could put them at a much lower risk of injury as a beginner or someone who is putting excess strain on joints.
Also, it goes without saying that if you’re working out in the aerobic zone, then you’re more likely to be using fat as fuel, and that’s the bit you want to get rid of. But if we’re in the fat burning zone during our day to day activities, But what most people DON’T consider, is the input; diet far outweighs exercise in the order of importance for dropping body fat. End of.
So if I want to lose fat, what SHOULD I be doing?
There is no big secret to fat loss. The formula is simple.
Calories Out > Calories In
There are numerous examples that show, it actually doesn’t matter what you eat, so long as you use more calories than you eat. Now obviously, there are healthier methods which also promote lean muscle and make you stronger and fitter while ensuring you get a good balance of all the nutrients you need, but the basic formula is very easy. And yes, before all of you start slating me about all the special exceptions, I am aware that this is for healthy individuals. If you DO have some kind of REAL DIAGNOSED underlying medical condition, then this may be slightly more complex, but for every day humans, this is it. Of course, executing that in the emotional, modern world we live in, is a lot more challenging, but once we stop telling ourselves that we’re ignorant and we don’t know HOW to do something, it suddenly makes it more realistic to be able to achieve it.
In terms of exercise, do what lights you up! If you love HIIT classes do that, if you love CrossFit, do that, if you love running, do that. Again, there are ways to carry on doing what you love to avoid injury and ensure long term progress and joy, but the nuances of that are for another article. If you’re looking to try and recompose your body and build some lean muscle, or at least avoid your body degrading muscle while you’re in a calorie deficit (which is essentially a state of “need” for your body, meaning it changes your metabolism and it can and will in desperate situations access available protein stores from things like muscles and organs if you don’t do it the right way…), then protein is important in your diet, but also stimulating your body to retain muscle through weightlifting is a great idea. This acts a constant nag and reminder to your body that your muscle is NEEDED. Think of it as a gentle nudge to your body to say “oi, don’t get rid of this muscle stuff, I need it to do this…”. But if you’re just looking to lose some fat and you want the easiest way to do it, get out there and do what you enjoy to move more!!
Don’t overcomplicate things. People love to recycle junk. They love to peddle whatever it is that supports their argument, even if it isn’t working. Most people who tell you you need to be working out slower and for longer, say it because that’s what THEY enjoy doing, not necessarily because it’s what works. Yes, it can work and yes, the fat burn zone is not something to forget about, because when considering overall fitness and health, it plays an important role in a training plan, but to rely on this and this alone for fat loss is setting you up for failure.