Exercising at an intensity that taps into your stored body fat sounds like a great way to slim down, but the benefits may not be what you think.

You step onto the exercise bike, elliptical machine, or treadmill, and it prompts you to enter your age, weight, and preferred program: manual, random, hills, intervals—or fat-burning.

The idea of working out in the fat-burning zone might seem like an effective way to get in shape, but does it really deliver the desired results? Or is the fat-burning zone just a relic of the fat-obsessed 90s, like SnackWell’s cookies and scrunchies?

In reality, experts agree that there is a specific exercise intensity range where your body burns more fat as a fuel source compared to glucose (sugar). People often refer to this range as the fat-burning zone, although it’s important to note that your body always burns some fat regardless of whether you’re walking or sprinting. Nevertheless, the concept of the fat-burning zone seems to be making a comeback, much like other 90s trends.

We consulted experts to understand the real results one can expect from working out in the fat-burning zone and how it compares to other aerobic exercises like interval training. Here’s what we discovered.

Using Fat as Fuel During exercise, your body utilizes stored carbohydrates (glucose) and fat as sources of fuel. The proportion of each depends on the intensity of your activity.

When you start any exercise routine, your body transitions from a resting state to a higher intensity. Initially, glucose is primarily used as fuel. As you maintain a low-to-moderate steady rate of exercise, the consumption of glucose decreases while the consumption of fat increases, according to Chris Scott, Ph.D., a sports medicine professor at the University of Southern Maine. In this low-to-moderate exercise range, fat becomes the predominant fuel source.

Understanding the Fat-Burning Zone Zone training is one approach to exercise, where intensity levels (low, moderate, high) are calculated as a percentage of your maximum heart rate (MHR) based on age. The fat-burning zone typically refers to maintaining about 60% to 70% of your max heart rate. At this intensity, approximately 65% of the calories burned come from fat, as reported by the Cleveland Clinic.

However, if you increase the exercise intensity to about 70% to 80% of your maximum heart rate—such as transitioning from a brisk walk to a jog or light run—only about 45% of the calories burned will come from fat.

Why Choose the Fat-Burning Zone? Burning more fat as fuel may seem like a promising strategy for losing excess body weight, but the benefits may differ from what you expect. Here are a few advantages of exercising in the fat-burning zone:

1. Suitable for Beginners: The fat-burning zone involves exercising at a moderate pace, making it an excellent starting point for beginners. It’s a lower-intensity approach that can be enjoyed alongside a partner, enhancing the social aspect of exercise and improving overall endurance, according to Derrick Van Every, an exercise physiologist.
2. Health Benefits: Lower-intensity cardio exercises, including those in the fat-burning zone, offer cardiovascular benefits similar to higher-intensity exercises. They can help lower blood pressure and cholesterol levels, reduce the risk of heart attacks and stroke, and prevent conditions like diabetes, metabolic syndrome, arthritis, and some cancers.
3. Improved Adherence: Many people find lower-intensity activities, such as brisk walking or recreational sports, more enjoyable and sustainable than high-intensity workouts. Enjoyment and adherence are crucial factors in maintaining an exercise routine, as confirmed by the Association for Applied Sport Psychology. Incorporating activities that you genuinely enjoy increases the likelihood of sticking with your exercise program.

Drawbacks of Fat-Burning Zone Workouts While the fat-burning zone offers certain benefits, there are reasons why maintaining low effort and intensity may not be ideal:

1. Lower Overall Fat Burn: Although the fat-burning zone emphasizes a higher percentage of calories burned from fat, the total number of fat calories burned may be lower compared to more intense workouts. Increasing exercise intensity, such as incorporating jogging intervals, can lead to a higher total calorie burn, including fat calories.
2. Time Commitment: Exercising at a lower intensity requires more time to burn the same number of calories as higher-intensity workouts. If weight loss is your goal, creating a calorie deficit by burning calories through physical activity and reducing calorie intake becomes essential, as noted by the Centers for Disease Control and Prevention.

Incorporating Interval Training Interval training involves alternating periods of higher-intensity activity with recovery periods. This approach can be more effective since working out at higher intensities burns more total fat, even if the percentage of fat calories is lower.

Interval training provides various benefits, such as improved cardiovascular fitness, lower blood pressure and cholesterol levels, better blood sugar control, and even potential cognitive benefits, as supported by studies published in the British Journal of Sports Medicine and Frontiers in Neuroscience.

It’s important to note that interval training may not be suitable for everyone, especially individuals with a history of heart disease or cardiovascular illness. If you’re considering high-intensity interval training (HIIT), it’s advisable to consult your doctor before starting.

Fat Burning through Strength Training While cardio exercises are commonly associated with fat burning, strength training also plays a role. Resistance exercises, using body weight or equipment, can contribute to fat loss and offer additional health benefits. Studies published in Sports Medicine and the FASEB Journal demonstrate the positive effects of strength training on reducing body fat.

Moreover, strength training has numerous health benefits, including healthy aging, improved mobility, cognitive function, and metabolic health in individuals with obesity and type 2 diabetes.

Finding What Works for You The great news is that you have flexibility in choosing your workouts based on personal preference and time constraints while still reaping the rewards. It’s essential to prioritize enjoyment and adherence to maintain a consistent exercise routine.

Mixing up your workouts can be beneficial, combining high-intensity sessions with lower-intensity exercises. Interval training can be an efficient option for those with time constraints, offering comparable benefits to longer, moderate-intensity workouts.

Remember to start with moderate intensity if you’re new to exercising, gradually progressing to higher intensities. Warming up and cooling down before and after vigorous exercise is also crucial to ensure safety and reduce the risk of injury.

Lastly, it’s important to listen to your body and find activities that you genuinely enjoy. Whether it’s biking, walking, dancing, or engaging in other recreational activities, finding something you love and can stick to is key.

Determining Heart Rate To optimize your workouts, it can be helpful to know your heart rate. There are several methods to measure it:

1. Smartwatches: Smartwatches such as FitBit Sense 2, Apple Watch Series 8, and Amazfit Bip U Pro provide convenient heart rate monitoring and other fitness-tracking features.
2. Manual Method: You can measure your heart rate by placing the tips of your first two fingers on the inside of your wrist or neck, counting your pulse for 30 seconds, and multiplying by 2.
3. Rate of Perceived Exertion: Assessing your perceived exertion based on factors like breathlessness, sweating, and muscle fatigue can provide a rough estimate of your intensity level. The National Academy of Sports Medicine offers a chart to guide perceived exertion levels.

In conclusion, the fat-burning zone can be an effective starting point for beginners and offers numerous health benefits. However, higher-intensity workouts, interval training, and strength training also provide valuable results, including increased fat burn and enhanced cardiovascular fitness. Finding the right balance and incorporating enjoyable activities into your exercise routine will ultimately help you achieve your fitness goals.