subject: The key to burning fat is the 30 minute threshold [print this page] The key to burning fat is the 30 minute threshold
When it comes to losing weight, a big obstacle to overcome is the general lack of understanding about how the body uses energy in the forms of sugars and fats during a cardiovascular workout.
Processing sugar
Carbohydrates are broken down into glucose and glycogen, which are also known as sugars. Glucose maintains blood sugar levels and is used by the brain as well as the heart for energy. Glycogen is stored in the liver and muscles. Any extra glycogen is transformed into fat. Glucose and glycogen can be broken down into energy without the need of oxygen. This is known as anaerobic metabolism which is utilized during anaerobic activities such as jumping, sprints or the dreaded "burpee" or squat thrust. This means that mostly sugars are used during short intense periods of exercise.
Fat cells
Fats cell are basically energy storage areas for the body. Believe it or not, your body needs fat to survive. However, too much fat (or obesity) is dangerous because it can inhibit normal functions of the body or it causes the body a great deal of stress. The problem with this stored energy is that it cannot be broken down very quickly. Therefore, fat stores can only be broken down through aerobic activity (e.g., running, swimming or biking for long periods of time).
Workout intensity
In order to achieve the "fat burning zone," one must be at the proper intensity. That is, you must exercise between 60% and 70% of your predicted heart rate based on your age, and resting heart rate. Any intensity greater than 70% will cause your body to burn a greater percentage of sugars and fewer carbohydrates (which isn't a bad thing but more on that another time). When one is between 60-70% of his/her target heart rate, he/she is burning the maximum amount of fat that the body is capable of burning.
The 30 minute threshold
There is one more important fact that we need to discuss. In order to get to the fat burning zone, the body must use a great deal of the sugars stored in the muscles before it can start breaking down the fat for energy. This is a process that generally takes about 20-30 minutes. This means a 30 minute activity, even an aerobic activity like running or walking, doesn't start tapping into the fat stores until the end of the workout!
While 30 minute workouts have their function and can help achieve better levels of fitness, it isn't something that is going to help reduce levels of body fat. Only those aerobic activities that last longer than 30 minutes, approaching closer to an hour or more, are going to help reduce the amount of fat stored in the body.
