Getting rid of excess fat is often the biggest motivation for gym goers, and rightfully so. Excess fat tissue harms our bodies in many ways – they contribute to insulin resistance and type 2 diabetes, high blood pressure, non-alcoholic fatty liver disease, weakened immunity, heart disease, and many other conditions. Not just obese and overweight people, but even people with normal body weight can experience damage from excess fat.

Enter the fat burning zone, a concept that claims to burn as much body fat as possible while exercising. Many gyms and fitness centers have fat burning zone charts on the walls that give a rough idea of ​​what pace a person should exercise at to lose the most fat.

What is the fat-burning zone?

Kushal Pal Singh, fitness and performance expert at Anytime Fitness, explains that the fat burning zone refers to the range of exercise and intensity where the body uses the maximum amount of energy from fat as a fuel source. When we exercise, the body uses a combination of carbohydrates, fats and to a lesser extent, proteins as fuel. The purpose of exercising in the fat burning zone is to use fat as the primary fuel.

This zone is generally equivalent to about 60-70 percent of a person’s maximum heart rate. In simple terms, your pulse should be between 60-70 percent of the maximum heart rate when you exercise. The intensity of such workouts is light to moderate, in which you can talk comfortably but may be a little breathless. You can use a smartwatch or fitness tracker to keep track of the pulse rate.

“Instead of consuming carbohydrates, which are the essential source for energy, the body consumes fat, leading to fat burning and therefore weight loss,” says Singh. “At this intensity, the body relies on aerobic metabolism, where oxygen breaks down fat molecules for energy. The rationale is that by exercising in this zone, one can optimize fat oxidation relative to carbohydrate utilization, potentially leading to greater fat loss,” explains Kate Austin, head coach at MultiFit.

Experts say that when the workout is light (but long), the body uses fat as fuel. For intense workout sessions, the body relies on carbohydrates.

How to calculate your fat-burning zone

Determining your fat-burning zone involves calculating your target heart rate range. You can use several methods.

Method 1:

A common method used to calculate the fat-burning zone is to determine 60 percent and 70 percent of your maximum heart rate. Generally, a person’s maximum heart rate is calculated by subtracting his or her age from 220.

For a 30-year-old, it would be 220-30=190. Do the basic math and find 60 and 70 percent of the maximum heart rate. In the case mentioned above, it would be 114 and 133. You can aim to work around this heart rate range.

However, instead of going by the general rule of calculating maximum heart rate by subtracting age from 220, you can calculate it manually for better results. Wear the smartwatch and walk or jog on a treadmill that feels easy to you. Increase the speed every 3 to 5 minutes until it feels hard and your heart rate stops increasing. Use this as the maximum heart rate for calculations. Consult a doctor first, especially if you have health issues.

Method 2:

Meanwhile, Kate Austin suggests using the Karvonen formula, which takes into account your age and resting heart rate.

Target heart rate = ((max heart rate – resting heart rate) — %intensity) + resting heart rate

First, calculate your maximum heart rate by subtracting your age from 220 or by doing it manually (explained above). Then, measure your resting heart rate by taking your pulse while at rest. Once you have both values, calculate your target heart rate range for the fat-burning zone by multiplying your maximum heart rate by the desired percentage intensity (usually 60-70%) and adding your resting heart rate.

To stay in the fat-burning zone, consider choosing steady-state cardio activities like brisk walking, easy jogging, cycling at a moderate pace, or swimming. “To see effective results, one needs to maintain consistency and exercise for a longer period of time, typically at least 30 minutes,” says Singh.

But, it also has its limitations

If you think you can rely solely on exercising in the fat-burning zone to lose weight and fat, you may be wrong. Fitness experts say that this cannot be the sole determinant of fat loss, as creating an overall calorie deficit is more important.

Body recomposition and transformation expert Avinash Mansukhani, who views the fat burning zone as a misleading concept, says, “While working in this heart rate zone, your body uses fat as a fuel source to work, but this does not mean that you will lose fat/weight from your body. This will only be decided by the calorie deficit over a cyclical period of time. Working at a higher intensity and burning more calories during your workouts can create a greater deficit that will lead to actual fat loss over time.”

Other experts agree. Kate says the concept of a fat-burning zone oversimplifies the complexities of metabolism. She says other factors, such as diet, total energy expenditure and genetics, can’t be ignored.

“Exercising only in the fat-burning zone is not necessary to lose fat quickly. While exercising in this zone emphasizes using fat, high-intensity exercise offers many benefits. For example, interval training and high-intensity interval training (HIIT) increase calorie expenditure and metabolic rate after exercise, leading to more calories burned overall. Another form of high-intensity exercise, strength training, builds lean muscle, which boosts metabolism and enhances fat loss over the long term,” she explains.

Ultimately, the best exercise for fast weight loss is the one you can do consistently — whether it’s in a fat-burning zone or not.