Hitting a heart rate that puts you in the “fat-burning zone” during your workouts doesn’t guarantee fat loss.
Whether you’re a seasoned gym veteran, or a complete workout newbie, tracking your physical stats is one common factor when it comes to exercising. And nowadays, it’s easier than ever to see how many steps you’re taking, how many floors you’re climbing, and what your heart rate is like at work and at rest.
If you take a look at most treadmills, or your fitness trackers, chances are you’ll spot a little chart that will tell you about “heart rate zones“; these nifty little zones that indicate what your heart’s beats-per-minute (BPM) is, and what physical benefit it’ll bring you.
It’s not really a surprise that most people want to end up in the “fat-burning zone” to get rid of all that annoying excess fat just hanging around. But if you think about it, how does your heart actually know it’s supposed to turn your fat-burning switch on according to how fast it’s beating?
As it turns out, your body does know when it’s ideal to start burning fat. Kind of. But it’s not just about getting your heart rate to a certain special target zone.
In a study referenced in The Washington Post, you actually burn more fat the less active you are. But before you start getting all excited about losing fat without doing anything, there’s more to it. Whenever you start an activity, you burn a certain ratio of fats and carbohydrates. The more intense your activity is, the greater the ratio of carbohydrates you burn compared to fat.
However, thinking about losing fat purely in these terms is not the most ideal when it comes to overall weight loss, especially when you start factoring in calories into the equation.
“The idea that all of a sudden when you hit this zone the fat is just being sucked out of your system is simplistic,” says Christopher Breen, an exercise physiologist and online coach in Long Island. “That completely ignores that losing or maintaining weight is basically a matter of calories in versus calories out.” What Breen is saying is that it’s more about the total amount of calories lost than purely fat lost that matters.
Christine Brooks, a University of Florida adjunct instructor and the coaching science coordinator for USA Track & Field, adds that performing less intense workouts isn’t really as effective overall compared to more intense workouts. “If you’re exercising at this lower intensity, you’re burning fewer calories per minute,” Brooks says. “The average person walking for an hour is going to burn only a couple hundred calories.”
Simply put, it’s more effective to think about your overall caloric deficit when it comes to weight, and fat loss, than it is to just focus on this mythical “fat-burning zone”.
“I have a real beef with the way this fat-burning idea is promoted,” Brooks says. “It’s a very strange way to talk about exercise.” Both Brooks and Breen have come to the conclusion that it’s popular simply because it’s easy for most people to understand. “It’s a way of making exercise machines more appealing — if I’m working at this speed, I’ll burn more fat than at another speed,” Breen says.
Plus, some much-needed HIIT can be more than beneficial for you in terms of overall fitness and giving your body a metabolic boost. “You maintain a higher metabolic rate after higher intensity exercise,” Brooks says. “The reason is that more damage is being done to various systems, so you have an increased heart rate while the body is making its necessary repairs.”
Having said that, it’s not entirely bad to incorporate some lower intensity workouts into your exercise routine. Not every workout needs to be full speed ahead where you end up lying in a pool of sweat and get sore for days.
“Mix it up,” Breen says. “Have some harder, high-intensity days, followed by easier, low-intensity recovery days.”
If you really want to see results, you just have to put in the work to get the body that you want. As enticing as it sounds to stay in that low-intensity fat-burning zone, it just simply doesn’t compare to bumping up the intensity for a more holistic and beneficial workout.
A version of this story first appeared on www.menshealth.com.sg.