It’s gym day. You step into the cardio room and climb onto your favorite treadmill. It’s time to burn big cals. But then, doubt kicks in. Do you pick the fat-burn, cardio, or interval setting? Gotta make it count!
If you’ve been fooled by the fat-burning zone on your gym’s cardio machines, don’t feel bad. It’s one of those exercise myths that refuses to go away.
Exercising in the fat-burning zone has been discredited as an effective weight loss strategy by countless fitness magazines, experts, and the American College of Sports Medicine. Yet it’s still with us because it’s partly true.
Yes, the fat-burning zone is real, but it’s not quite helpful for losing significant amounts of fat. And you’re about to find out why.
What Is the “Fat-Burning Zone”?
Treadmills, ellipticals, and step machines are common gym machines that offer settings for different workout zones. The two most common ones—“fat-burn” and “cardio”—correspond with exercise intensity.
Ever confessed your age to an exercise machine? Don’t lie—it’s used to predict your maximum target heart rate (HR), a.k.a., the upper limit of what your cardiovascular system can supposedly handle during exercise. What it means to be in the…
Fat-Burning Zone: Exercising at a pace that makes your heart beat at 60 to 75 percent of your max HR.
Cardio (or Aerobic) Zone: Exercising at a pace that makes your heart beat at 75 to 85 percent of your max HR.
Pick fat-burn and you’ll run at a relatively low intensity. Pick cardio and you’ll huff at a faster pace.
The Link Between Exercise Intensity and Fat Burn
Here’s where we tell you why the fat-burning zone exists.
Your body burns calories 24-hours a day regardless of whether you’re moving or not. But when you move—be it fidgeting at your desk, playing tag with your kids, or pounding the pavement in your section of town—you burn more calories, and the extent of that burn is directly related to the intensity of your activity.
Whether those calories come from fat or carbs (in the form of glucose) is also influenced by exercise intensity. Research shows that low intensity exercise, like walking or jogging, burns a larger proportion of fat as fuel (hence the “fat burning zone” on cardio machines). Moderate to high intensity exercise (e.g., running, sprint intervals, and circuit training) causes the body to shift primarily to glucose, which can be broken down to supply energy at a faster rate.
Here’s the catch: The fat-burning zone may help you burn a larger proportion of calories from fat as you work out, but high intensity exercise keeps your metabolism raised for longer after you finish, helping you burn more calories (and fat) overall. The tragedy of the fat-burning zone is that it misleads people into thinking they don’t have to challenge themselves to see results.
That said, always listen to your body—pushing your physical limits won’t feel comfortable, but it shouldn’t be unbearably painful either.
3 Tips for Getting in the Real Fat-Burning Zone
Next time you’re on a cardio kick, use these tips to get more more fat-burning benefits from your workouts.
Use the manual setting
You can still use the zone settings on workout machines as a guide, but don’t zone out after that. Assess how you feel during your workout. Is it too hard? Too easy? Manually change speed and elevation to challenge yourself. Hint: If you can carry a conversation while moving, bump up the intensity!
Steady state cardio shouldn’t be your only strategy if you want to optimize fat loss. Indeed, strength training is an even more effective strategy in that regard, because it keeps your metabolism elevated for longer after you work out, helping you burn more calories overall. And the benefits don’t stop there — especially if you’re a cardio junkie, as resistance training can help increase running speed, economy, and power output. What’s more, studies show that it can increase time to exhaustion and reduce your risk of injury. So try replacing at least one cardio session per week with a strength session.
Try high-intensity interval training (HIIT)
HIIT is an exercise strategy in which you alternate periods of intense activity (80 to 90 percent of your maximum effort) with less intense periods of rest. Circuit training, sprint drills, and stadium stair running are all examples of HIIT. You’ll also find it in most of the workout programs on Beachbody on Demand. The idea is that you repeatedly push your body to its limits, focusing on workout density and intensity rather than duration.
Studies show that HIIT causes the greatest increase in “excess post-exercise oxygen consumption” (EPOC), which is the amount of oxygen required to restore the body to its normal resting state. Here’s why that matters to you: The higher your EPOC, the more calories you’ll burn post-workout.
Although HIIT is the most effective form of exercise for losing weight, it’s not always the best choice for beginners. If you’re new to exercise, or are getting back into it after a long absence, save HIIT for when you’re built a solid fitness foundation. That way, you can optimize fat loss without increasing your risk of overtraining or injury.