When we burn calories as we attempt to lose weight there are some important factors to keep in mind. Our bodies have a very intricate mechanism for utilizing energy very efficiently. Due to this fact it is important to understand how to engage the right energy system for maximize energy utilization and calorie expenditure.
The human body actually has three energy systems that are used to varying degrees depending on the intensity level and the duration and of activity you're engaged in. During activity the human body will utilize all three energy systems to provide energy, but only one energy system will be the primary contributor.
The first energy system to be engaged is called the phosphagen system, and it's activated for short-term high intensity activities that take between 0 and 6 seconds. Sprinting, throwing or jumping would be example of such activities. The second energy system, called the glycolysis system, is activated for activities ranging from 6 seconds to 3 minutes. Activities that use the glycolysis system as the primary source of energy include running and swimming short distances. The final energy system is called the oxidative energy system. The oxidative energy system supplies energy for long-term activity such as walking, jogging, distance running, cross-country skiing, soccer and ultra-endurance events.
As the body moves it expends energy. The level of movement determines the source and the amount of energy that is expended. When the goal of exercise is to reduce body fat through calorie expenditure, the exercise must be performed at the correct intensity level for an adequate time frame (30 minutes or more). This will allow the body to tap into the proper energy system(s) for body fat reduction.
The oxidative energy system primarily uses stored body fat and oxygen to burn excess fat during exercise when the intensity level is low enough. The intensity level of the exercise should be between 60 and 70 percent of the maximum heart rate range. The body switches between energy systems during exercise to keep up with energy demands, but if the demand is not too high (low intensity exercise) the main source of fuel will come from the target source, stored fat.
To maximize body-fat reduction it is also important to:
- Consume less calories than you expend per day
- Engage in low-intensity physical activity for 30 minutes or more each day
- Consume low calorie, highly nutritious foods i.e. fruits, vegetables, whole grains, beans, seeds as the major source of your calories each day
Make a commitment to the above lifestyle adjustment; it is impossible to achieve any measure of success if there is no conscious effort to do so. Be patient with yourself success will not come in one day!
How do you eat an elephant--one bite at a time -Anon
Source: Essentials of Strength Training and Conditioning