Heart Rate Zone For Fat Loss

Fat loss occurs when the amount of energy expended by the body through exercise and daily activities exceeds the amount of energy consumed through food. During sleep your body expends about 50 to 100 calories per hour. However, during vigorous exercise when your heart rate is elevated your body may expend 500 or more calories per hour depending on your weight and gender. Your heart rate indicates how hard you're working during exercise, and a higher heart rate equals a higher amount of energy expended.

Heart Rate & Energy Sources

To convert fat to energy requires oxygen, which you have plenty of while you're sleeping. Consequently, during sleep your body receives most of its energy from stored fat to perform basic bodily functions, such as breathing. However, as you exercise, you have less and less oxygen available for fat conversion until your body burns only stored carbohydrates instead. The heart rate range in which you're expending significant energy but still have oxygen available for fat conversion has come to be known as the "fat burning zone." It is around 65 to 75 percent of your maximum heart rate.

Misconceptions

The problem with the "fat burning zone" is that it burns less energy overall than a workout in a higher heart rate zone or interval training. Think of it this way: you could exercise at a moderate pace to burn the equivalent of 300 calories from stored fat during your workout. Or you could exercise at a vigorous pace to burn 500 calories from stored carbohydrates. The source of the energy is of less importance than the total amount of energy burned. At the end of the day, the greater the energy deficit the greater the fat loss.

Potential

According to a study published in the December 7, 2006 issue of the Journal of Applied Physiology, two weeks of high-intensity aerobic interval training resulted in 36 percent more fat burning during exercise. Study participants increased their cardiovascular fitness during the trial which may have been responsible for the increase in fat burning due to an increase in oxygen available for fat conversion. In the study, participants exercised for one hour with repeated bouts of four minutes at a vigorous pace yielding an elevated heart rate followed by a two-minute recovery period. Thus, interval training may yield greater fat loss overall than simply exercising at a moderate to intense pace for extended periods of time.

Staying Safe

To calculate your maximum heart rate, subtract your age from the number 220. For example, if you are 30 years old, your maximum heart rate is 190. Do not exceed your maximum heart rate. Doing so is dangerous because it puts undue stress on your cardiovascular system.

Expert Insight

According to Katherine Zeratsky, R.D. of the Mayo Clinic, though light physical activity---such as walking or gardening---has some weight loss benefits, the greatest fat loss occurs from activities that are moderately intense and raise your heart rate more significantly. The National Academy of Sports Medicine concurs and says that exercising at a higher heart rate yields greater fat loss than training in the less intense "fat burning zone."