As we move through our busy lives, it’s easy to overlook the incredible biological processes that underpin our very existence.
Our bodies continuously work behind the scenes, performing magical routine tasks like breaking down food into essential nutrients, synthesizing new building blocks for cells and tissues, and pumping nutritious blood throughout our bodies.
These processes work in harmony, keeping us healthy and functioning efficiently.
The Science of Fat Burning
Our bodies need energy to do all the things it needs to do. This energy generally comes from the food we consume—from the carbohydrates, fatty acids, and proteins we get from those foods.
Carbohydrates are generally the easiest and quickest for our bodies to break down, so they tend to be prioritized as the first source of energy we use. However, when our glycogen stores (the storage form of carbohydrates) start to run low, our bodies shift their focus to other energy sources, such as fat.
Fat burning is also influenced by the action of certain hormones that regulate our metabolism and energy. Adrenaline and cortisol, for example, trigger the release of stored fatty acids from adipocytes (fat cells).
When these hormones surge, as they do during exercise, the body more readily mobilizes fat for energy production.
Heart Rate and Fat Burning
When you engage in heart-pumping physical activity, you’ll quickly burn through your glycogen stores and start breaking down stored fat tissues for energy.
This has led to the concept of the “fat-burning heart rate“—the idea that there’s an optimal range of heart rate that maximizes fat burning during exercise.
To better understand this, it may help to first understand two similar key concepts: resting heart rate and maximum heart rate. Resting heart rate refers to the number of times your heart beats per minute when you’re at complete rest. This is generally between 60-90bpm.
Maximum heart rate, on the other hand, is the fastest rate your heart can safely beat. This is generally calculated by subtracting your age from 220. In other words, it is dangerous for someone who is 70 years old to reach above 150bpm, but for a 30-year-old, as a general rule, they can safely reach higher beats per minute.
The fat-burning heart rate zone is typically considered to be between 60% and 80% of your maximum heart rate. When you’re exercising within this range, your body is thought to be most efficient at tapping into its fat stores for energy.
Optimizing Your Exercise
To make the most of this knowledge, you can try taking the following steps:
- Determine your maximum heart rate: Subtract your age from 220 to get an estimate of your maximum heart rate.
- Calculate your fat-burning zone: Multiply your maximum heart rate by 0.6 and 0.7 to find the lower and upper limits of your fat-burning zone.
- Monitor your heart rate during exercise: Use a heart rate monitor, fitness tracker, or simply check your pulse to ensure you’re training within your fat-burning zone.
- Adjust your workout intensity: If you find that you’re consistently above or below your target heart rate zone, adjust your exercise intensity accordingly. This may involve increasing or decreasing the speed, incline, or resistance of your workout.
Is This Actually Useful?
While understanding the fat-burning heart rate and working within that zone can be beneficial for some individuals looking to optimize their workouts, it’s not the be-all and end-all of effective exercise.
The fat-burning zone is relatively broad, so doing any type of exercise at all will generally put you in that range.
The core idea behind the fat-burning heart rate is that you won’t burn much fat if you aren’t active at all, and also, maximum intensity may not be optimal for fat-burning either. But anywhere in that moderate-to-high range of intensity will likely be good for both burning fat and improving your cardiovascular fitness.
Additionally, the type of exercise you choose, the duration of your workout, and your overall diet and lifestyle play significant roles in your body’s ability to burn fat effectively. So, while it may be useful to be aware of your fat-burning heart rate, for most people, it might not be worth getting too caught up in the numbers.
