Your body has plenty of options when it comes to fuel reserves. It can burn off Carbohydrates, Fats and even Proteins, as fuel, and provide with that energy that enables you to perform various activities. Your body’s choice of reserve depends on the severity of the activity you’re performing. For normal chores and various bodily functions, the human body likes to burn off Glycogen reserves that are extracted from Carbohydrates. But for activities that are more physically demanding, the body can switch over to your fat reserves or the fat in your food or under extreme condition, it can switch to consumption of lean body mass! So the question is how does heart rate determine fat consumption and what is the heart rate for fat burning?
The heart rate plays an important role in determining what kind of activity you’re engaging in. The body uses other triggers as well but heart rate is an important factor. Physical activity is all about energy expenditure. When the activity becomes more strenuous, your body demands a higher energy and a higher Calorie loss. The energy extracted from Carbohydrates (Glycogen) stands at 4 Calories per gram. Same is true for Proteins as well but in the case of Fats, this energy output becomes 9 Calories per gram. For this reason, at times of peak physical activity, your body switches to a Caloric dense alternative to provide more energy for the activity you’re engaging in.
Rigorousness of an activity is determined by heart rate. To enable your body to switch to your fat reserves, you have to maintain your heart rate at a certain range. To understand this in detail; firstly you’ll have to calculate your maximum heart rate. A simple formula to do this is:
Max heart rate = 220 – (Age)
Now that you have your maximum heart rate, the rest of the discussion will be done in terms of %age of your maximum heart rate. Here are some of the training zones:
Warm-up Zone: 50 – 60% of HR(Max)
This is a very good training zone for people who are just starting with some physical activity. There’s no strain on the heart and the risk of injury at this HR is very low. At this level, 75% of the Calories come from Fat.
Fat Burning Zone: 60 – 70% of HR (Max)
The percentage of Calories that come from Fat are almost the same (80 – 85%) but since the training is more vigorous, you lose more overall Calories from other c\sources as well. Activities like brisk walk, jogging and light cycling come under this category.
Endurance Training Zone (Aerobic): 70 – 80% of HR (Max)
The percentage of Calories that come from Fat fall in this zone (50 – 60%) but overall, you lose more Calories. This zone is very beneficial for cardiovascular health, respiratory system and muscular endurance.
Performance Training Zone (Anaerobic): 80 – 90% of HR (Max)
The percentage of Calories is almost same as the Endurance Training Zone (50 – 60%) but overall, you lose more Calories. High intensity weight training falls in this category.
It becomes clear that the ideal fat burn heart rate is in the range of 50 – 70% of your maximum heart rate. You can keep track of your heart rate during your training sessions by wearing a Heart Rate monitor with some sort of external display. This will give you a good idea which zone you’re hitting and what your target should be.